the institute for surface chemistry , yki ( the swedish name is ytkemiska institutet ) is an industrial research institute in applied surface and colloid chemistry located in stockholm , sweden .

it is located on the campus of the royal institute of technology ( kth ) .

yki 's mission is to transfer and develop innovations to customers in industrial sectors where surface chemistry plays an important role .

the areas of expertise lie in the fields of surface and colloid science .

it has a staff of approximately 65 persons .

yki is a part of the sp group , sp technical research institute of sweden .

the work within yki is organized in three sections , materials and coatings section , forest products section and life science and chemical industries section .

institute for surface chemistry

dynamics of knowledge production in the swedish institute for surface chemistry , 1975 - ‐2005 .
designed by s . snegir for : chuiko institute of surface chemistry . all rights reserved .
on 1 january 2013 , yki , institute for surface chemistry and its parent company , sp technical research institute of sweden , will merge .
the institute of petroleum chemistry sb ras was established in 1970 for comprehensive studies into chemistry of west siberia oils .
© 1996 - 1998 , institute of petroleum chemistry of sb ras , tomsk .
the department of chemistry is one of the largest departments at the royal institute of technology . it consists of four divisions : applied physical chemistry , glycoscience , organic chemistry and surface and corrosion science .
there is a post - graduate course on petroleum chemistry and a dissertation council at the institute .
chuiko institute of surface chemistry was founded on the 8th of may 1986 as the first academic institution in the soviet union to study fundamental and applied problems in chemistry , physics and technology of solid surfaces . it was based on the surface chemistry section ( two scientific departments and special design - technical bureau ) of l . v . pisarzhevskii institute of physical chemistry of academy of sciences of ukrssr . read more . . .
fundamental investigations in oil composition and properties ; physico - chemistry of oil systems and surface phenomena ; creation of information systems on oil chemistry and geochemistry .
institute of catalysis and surface chemistry , polish academy of sciences was established in 1968 as the only independent scientific institution in poland , and one of only eight in the world , devoted entirely to the research in catalysis and chemistry of interfaces . among 60 persons of scientific staff of the institute there are 16 professors and associate professors ( docent ) specialising in various aspects of catalysis , surface chemistry and colloid science .
yki – the institute for surface chemistry – has appointed peter alberius as acting president . former president bruce lyne and vice president mats andersson have been relieved from their duties by yki ' s board of directors .
in 1970 a department of high - molecular compounds of the tomsk state university was organized at the institute for training specialists . the department is traditionally headed by the director of the institute .
on january 1st 2013 , yki , institute for surface chemistry and sp’s existing chemistry and materials business merged to form a new unit within the sp group . the merger means that yki will no longer exist as a stand - alone company , but will continue with business as usual in stockholm .
“the board of yki , management of sp and the association for surface chemistry research ( fyf ) all believe that peter alberius is the right person to manage the changes that are needed in order for yki to succeed in taking the next steps in its development to become a world - leading research institute in surface chemistry , ” says maria khorsand , ceo of the sp group .
director , center of interface dynamics for sustainability , chengdu development center for science and technology , china academy of engineering physics 355 , tengfei er road , southwest airport economic development zone shuangliu , chengdu , sichuan 610207 , people’s republic of china m : + 86 186 8343 5191 ( china ) ; + 31 6 51142839 ( the netherlands ) e : a . w . kleijn @ urltoken visiting professor / advisor at : - surface physics and chemistry laboratory , caep , jiangyou , people’s republic of china - van & apos ; t hoff institute for molecular sciences , faculty of science , university of amsterdam , the netherlands - fom institute differ - dutch institute for fundamental energy research , nieuwegein , the netherlands - leiden institute of chemistry , gorlaeus laboratories , leiden university , the netherlands employment history 1974 research assistant , fom institute for atomic and molecular physics 1975 - 1980 research associate , fom institute for atomic and molecular physics 1980 - 1981 postdoctoral fellow , ibm san jose , ca , usa 1981 - 1999 research staff member , fom institute for atomic and molecular physics 1987 - 1999 professor of physics , university of amsterdam 1999 - professor of chemistry , leiden university 2003 - director , fom institute for plasma physics rijnhuizen
we are looking for a highly motivated postgraduate student to undertake a msc by research in surface chemistry whereby modifications of the surface with attachment of chemical groups to enhance the proliferation and differentiation of mesenchymal stem cells .
the institute has a block of model installation to bring new technologies into a commercial level .
yki , which is part of the sp group , specialises in applied surface and colloid chemistry and has an international lead in several areas .
it was established on 1st january 1968 initially as research laboratories of catalysis and surface chemistry having the scientific council jointly with the institute of physical chemistry of the polish academy of sciences in warsaw . from 1968 to 2002 it was directed by professor jerzy haber . since 28th november 1978 , when the appropriate decree of the council of ministers of poland was issued , it exists as an independent institute with its own scientific council . since 1990 the institute has rights to grant phd degree in physical chemistry and since 2000 it has habilitation ( dsc ) rights . the institute is a member of marian smoluchowski krakow scientific consortium ' matter - energy - future ' , which since 2012 has a status of national leading scientific center ( know ) .
a unique petroleum museum has been created at the institute containing mone than 3000 petroleum samples and cores . they are also used as the subjects for scientific researches .
urltoken will not be updated but will remain in its current state until we launch new pages for sp chemistry , materials and surfaces at urltoken .
the research aim of the catalysis and surface chemistry group headed by prof . marc koper is to probe and understand chemical reactions on well - defined , mostly single crystalline , surfaces at the molecular level .
the research activities of the institute cover the interdisciplinary field of catalysis and the physical chemistry of phenomena occurring at solid / gas , liquid / gas and solid / liquid interfaces with an emphasis put on their significance and mechanism in catalysis , flotation , adsorption and detergency .
yki has offered our customers innovation - driven applied research within surface and colloidal chemistry for nearly 50 years . we carry those years with a lot of history , competence and pride that we now bring with us into the next step - an exciting future within the sp group .
the employment in the institute evolved from 28 persons when it was established in 1968 to 92 persons in 2001 including 42 research staff with 15 professors and associate professors ( docent ) specializing in various aspects of catalysis , surface chemistry and colloid science . currently , the number of institute ' s employees is above 100 , of which 2 / 3 are research staff . over 20 phd and many undergraduate students are also involved in the research . there are 14 independent research groups and four laboratories that provide services for scientific community : laboratory of surfaces and nanostructures , joint laboratory of biotechnology and enzyme catalysis and national research center for magnetic nanostructures ( spinlab ) .
how to cite this article : song , e . et al . surface chemistry governs cellular tropism of nanoparticles in the brain . nat . commun . 8 , 15322 doi : 10 . 1038 / ncomms15322 ( 2017 ) .
b . sc . ( university of toronto , 1979 ) m . sc . ( university of toronto , 1981 ) ph . d . ( university of toronto , 1985 ) nserc postdoctoral fellow ( imperial college , 1985 - 87 ) director , nserc create in neuroengineering ( 2011 - 17 ) president , mcgill association of university teachers ( 2014 - 15 ) chair , chemical institute of canada ( 2014 - 15 ) president , canadian society for chemistry ( 2009 - 10 ) fellow , chemical institute of canada ( 2013 ) fellow , royal society of canada ( 2012 ) fellow , royal society of chemistry ( uk ) ( 2010 ) leo yaffe award for excellence in teaching , mcgill ( 1996 )
the de vos group is part of the centre for surface chemistry and catalysis ( centrum voor oppervlaktechemie en katalyse ; cok ) , a large interdisciplinary team ( > 120 people ) involved in research in the chemistry of the solid - gas , solid - liquid , and solid - solid interphases . the group currently consists of 9 post - doctoral researchers and 17 phd students under the wings of professor dirk de vos .
thanks to the merger between yki and sp ' s chemistry and materials unit , we offer you a unique and broad competence within chemistry and materials technology that is hard to match in terms of product development and analyses . the new unit , sp chemistry , materials and surfaces , form the sp group ' s biggest unit with 160 experts - almost half have a phd degree . you get :
alexander kandratsenka’s group supports experimental efforts with first principles simulations of molecule - surface dynamics with coworker svenja janke .
fig 1 . extruder for krüss dsa contact angle machine ( left ) , and fig 2 . environmental chamber for the contact angle machine ( right )
we co - own a bet surface area analyser which is situtated in the department ' s analytical services laboratory . the
ced in tumour - bearing rats was conducted following the exact same procedure as for the healthy rats , by reopening the burr hole used for tumour implantation .
this work was supported by the national institute of health ( nih r01 ca149128 ) and the brain research foundation . a . g . was supported by the leslie h . warner postdoctoral fellowship from the yale cancer center . the authors thank marc llaguno for tem assistance . we thank muneeb mohideen , elias quijano , junwei zhang , david chi , dr fred gorelick and dr jiangbing zhou for insightful discussions and paul won for technical assistance .
surface / group / diebold / index . txt · last modified : 2018 - 06 - 14 18 : 20 by michael schmid
the activities of the institute cover the interdisciplinary field of the physical chemistry of phenomena occurring at solid / gas , liquid / gas and solid / liquid interfaces . the institute integrates fundamental theoretical and experimental studies and combines them with applied research whose results can be directly used to improve technological processes . about one third of the research activities is connected with colloid and interface science . the main topics of expertise are : transport phenomena in colloid systems ; colloid and nano - particle adsorption , formation of composite coatings ; adsorption of polymers and polyelectrolytes ; surface and electric properties of polyelectrolyte layers ; interactions in disperse systems and their stability ; electrokinetic phenomena ; surfactant systems , adsorption , wetting ; electrochemistry and photocatalysis .
a corresponding - member of the ussr academy of sciences michael f . shostakovsky was the organizer and the first director of the institute in 1970 - 1973 . later the institute was headed by professor yury g . kryazhev ( 1973 - 1978 ) , dr . anatoly n . plyusnin ( 1978 - 1981 ) and by a corresponding - member of the ussr academy of sciences gennady f . bolshakov ( 1981 - 1989 ) .
2012 – 2017 divisional associate editor ( materials physics ) for physical review letters 2017 – 2019 advisory board , acs energy letters 2016 – advisory board , npj quantum materials 2013 – 2015 advisory board , advanced materials interfaces 2010 – 2015 advisory editorial board for surface science 2009 – 2010 reader panel , nature 2009 guest editor ( together with t . m . orlando ) , “non - thermal processes on surfaces . dedicated to the memory of prof . theodore e . madey” special issue in j . phys . : cond . matter 2007 – 2010 advisory editorial board for open journal of physical chemistry 2006 – 2007 guest editor ( together with a . selloni and c . di valentin ) , “doping and functionalization of semiconducting metal oxides” , special issue in chemical physics 2006 – 2007 surface , interface and atomic - scale science editorial board of journal of physics : condensed matter 2003 – advisory editorial board for surface science reports
icsc pas is a parent institution for the international postgraduate school , organised in cooperation with the faculty of engineering and chemical technology of the krakow university of technology , and the faculty of chemistry of the rzeszów university of technology . the school is attended by over 50 phd students . in the framework of collaboration with the jagiellonian university , icsc offers the possibility of preparing the msc and bsc theses in chemistry and environmental protection .
description of expertise aart w . kleyn received a bachelors in chemistry and mathematics at leiden university in 1972 , and a masters in physics with mathematics and geochemistry at the university of amsterdam . he obtained his phd in physics at the same university in 1980 , cum laude . he worked as post doctoral fellow with ibm research in 1980 - 1981 . he was a member of the scientific staff of the fom institute for atomic and molecular physics ( amolf ) in amsterdam from 1981 until 1999 . he became professor of physics at the university of amsterdam in 1988 . he was head of the atomic and molecular physics divisions of the fom institute for atomic and molecular physics . in 1999 he left amsterdam and joined the faculty of leiden university as professor of chemistry . in 2003 he became director of the fom institute for plasma physics rijnhuizen . prof . kleyn served on many boards and committees nationally and internationally . he was president of the netherlands physical society ( 1998 - 2001 ) . he was president of the physics education division of the european physical society . he is editor of the journal progress in surface science , and serves on the board of several international journals . he has organized and co - organized many international conferences . he chaired two international research networks sponsored by the european union . he was elected into the selection and scheduling board of the gordon research conferences ( usa ) . he is a fellow of the institute of physics ( uk ) . he is a member of the american vacuum society , the american physical society , the european physical society , the netherlands physical society ( nnv ) , the netherlands vacuum society ( nevac ) , the royal dutch society of science ( haarlem ) , the royal netherlands chemical society ( kncv ) , and the royal society of chemistry ( uk ) .
reusable adsorbents have been developed to collect oil and oil products from water surface . their production and use have been brought into a commercial level .
one example of an area where yki and sp ' s previous chemistry and materials unit complement each other especially well after the merger is the polymer area . here we can now offer you a one of a kind one - stop - shop resourse . thanks to our combined expertise we can work across the whole polymer field - for example syntheis , characterisation of polymer surfaces and sturctures , formulation , surface modification etc .
contact corresponding author for matlab code regarding analysis of volume of distribution of nps in the brain .
moreover , each year icsc pas organizes open day which aims at popularization of the catalysis and the surface science among pupils from primary and secondary school .
this means we will be able to offer you a unique and broad competence within chemistry and materials technology that is hard to match in terms of product development and analyses . you get :
preference will be given to applicants with basic degree in science such as materials science , chemistry , medical physics or related subject , with a minimum cgpa above 3 . 0 , with good english proficiency . the candidate needs to have a strong interest in surface modification as well as biological knowledge , with a passion in research , self - motivated and able to work independently .
devices for scientific researches , i . e . densimeters , microcalorimeters , viscosimeters , cryostats and petroleum quality analysers .
on 1 january 2013 , sp will merge its subisidiary yki and its chemicals business in borås into a single unit within the sp group . the aim is to create a strong centre of excellence within the field of chemistry .
students undertaking any of these projects will gain experience in physical organic principles , spectroscopic methods , electron microscopy , electrochemical techniques , and surface chemistry . recent graduates and pdfs are currently in academic positions ( u . de montréal , guelph , saskatchewan , concordia , rutgers , waterloo , laurentian , dalhousie ) , government research labs ( nrc ) , and industry ( charles river , stemcell ) , and postdoctoral research positions .
methods for judicious use of natural caustobioliths , waste of oil refining , coal , peat and other organic raw material processing .
the contact angle is the angle at which a liquid / vapor interface meets the solid surface . the contact angle is specific for any given system and is determined by the interactions across the three interfaces . using the dsa from krüss gmbh we probe the surface using a variety of test liquids to obtain contact angles and subsequently the surface energy of the sample material . hydrated ( or wet ) samples can also be characterised using the captive bubble technique . advancing and receding angles can be meaured by expanding and contractnig the test liquid ( or air ) on the substrate or by tilting the table , which also allows to determine sliding angles . hot melts and their interaction with surfaces ( such as powder beds ) can also be studied up to tempeatures of 400°c .
we have a wide range of optical microscopes , which are interfaced with digital cameras and image analysis software for measuring ( e . g . pore sizes ) . we have linkham hot plate and cold stage accessories for studying the development of crystallini ty of polymers over time , this is also used to identify the site of nucleation ( i . e . from the surface of carbon fibres ) . we also have access to scanning electron and transmission elctron microscopy in the department of materials .
the rise institutes sp , innventia and swedish ict have merged in order to become a stronger research and innovation partner for businesses and society .
chemistry : a series of research - level seminars about topics of current interest in advanced materials . topics include molecular and nanoelectronics , computational approaches to materials design and property predictions , new techniques in molecular and atomic imaging , advances in materials preparation , quantum devices and quantum computing .
) . the different nps were also administered to rats bearing gfp expressing rg2 tumours grown for 7 days . all formulations yielded volumes of distributions (
surface and interfacial tensions ( i . e . contact angles , captive bubbles / drops , interfacial tensions ) at elevated tempartures and pressures are required in the development of materials or the understanding of phenomena relevant to the oil and gas industry .
raising the productivity and competitiveness of european businesses through technology . boosting national economies on the international market , and strengthening the basis for sustainable prosperity and employment .
for immunostaining and imaging , brains were fixed in 4 % pfa for 24 h and placed in a 30 % sucrose solution until it equilibrated and sank . tissue was then sliced using a leica cm3000 cryostat ( leica ) to 10 μm slices and stored at −20 °c until staining . just before staining , slides were rehydrated with pbs and then permeabilized with 0 . 1 % triton - x for 1 h . the slides were then washed three times and incubated in blocking buffer ( 5 % bsa , 5 % donkey serum and 0 . 05 % triton - x solution ) for 1 h . slides were incubated with primary antibodies ( anti iba1 rabbit ; wako pure chemicals , richmond , va , usa ; anti gfap rabbit , bs - 0199r ; bioss antibodies ; anti neun rabbit , ab1044225 ; abcam , cambridge , ma , usa ) diluted to 1 : 500 in blocking buffer for 18 h at 4 °c . slides were washed three times with blocking buffer for 10 min each and then incubated with secondary antibodies ( goat anti rabbit cy5 , a10523 ; life technologies ) diluted to 1 : 1 , 000 in blocking buffer for 1 h at room temperature . finally , slides were washed two times with blocking for 10 min and once with water , then mounted for imaging using vectashield hardset antifade mounting medium with dapi ( vector laboratories , burlingame , ca , usa ) . images were taken using a leica tcs sp5 confocal microscope ( leica ) .
can be attained by the bet isotherm method , whereby nitrogen is adsorbed and subsequently desorbed . the size of a nitrogen molecule is known , therefore by monitoring the mass change over time , the surface area of a known mass of sample can be attained .
the institute has also notable achievements in developing technologies for protecting the environment . one of them - swingtherm - is a novel catalytic , low - energy - consumption process based on the regenerative catalytic oxidation , targeted at the purification of industrial waste gases , which found application in poland , europe , and overseas . in 1995 , a spin - off company katalizator ltd . was created , in order to promote the industrial implementation of catalytic materials designed at icsc . this company , in which icsc holds a control share packet , produces and sells catalysts synthesized according to icsc - patented procedures to industrial partners all over the world . in 2007 a centre for environmental pollution analyses has been established , offering services to the customers from the whole country .
research in this laboratory is oriented around structure / property relationships of classes of molecules which form interfaces and nanomaterials . this takes us into molecular design and synthesis ( of novel surfactants and lipids ) , kinetics studies ( enzymology ) , surface chemical techniques ( langmuir films , electrochemistry , scanning probe microscopy ) , spectroscopy ( nmr , ir ) and polymer chemistry . in addition to the research that is performed directly in our labs , we also work with researchers in physiology , physics , chemical engineering , and neurosciences on collaborative projects . some examples of ongoing projects in this laboratory include :
the group combines state - of - the - art experimental setups to study surface catalytic reactions using a variety of spectroscopic techniques , both at the metal - uhv and metal - liquid interface , with computational techniques based on density functional theory and dynamic monte carlo simulations .
to augment the main effort of our lab , which is experimental in nature , we also carry out forefront research in theoretical modeling of surface chemistry and dynamics . density functional theory , quantum dynamics , and mixed quantum classical methods are all key approaches that allow us to reproduce experimental observation from first principles in a computer simulation . with the most highly developed theories that faithfully reproduce a variety of experimental observations , we may explore molecular dynamics at surfaces in much greater atomic level detail through the methods of computer simulation . the independent - electron surface hopping approach is one such method that we are presently applying in close collaboration with its inventor , prof . john c . tully of yale university . aspiring to take the maximum advantage of new theoretical methods , we use cpu and gpu ( graphic processor unit ) clusters to utilize the power of modern technologies of parallel computing .
a system for complex studies of oils . logical structure of integrated gis data base has been created ( nearly 40 mb ) including geological , chemical , physico - chemical information on oils as well as technological and ecological information on the territories of oil fields in the tomsk region , software to reveal zones of ecological hazard and software for cartographic data mapping .
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for volume of distribution experiments , a biological replicate of three was performed to ensure reproducibility and accuracy of our data , as previously reported in literature by our group . for flow cytometry , a biological replicate of five was performed to repeat the experiment on three different days , accounting for any processing variables and to ensure day to day variation . moreover , preliminary experiments demonstrated that n = 5 was sufficient to ensure the detection of significant differences . animals that died during procedures were not processed further for analysis . for the therapeutic efficacy study , an initial number of 10 animals per group was previously shown in our group to ensure statistical differences . animals dying without waking up from surgery ( after tumour implantation or ced ) were excluded . animals were randomly assigned to the different groups to prevent any confounding variables from syringes or stereotactic frames . investigators were not formally blinded to experimental groups .
( a ) schematic of pla - based nps with different surface coatings . ( b ) particle morphology and population was imaged using tem after staining with uranyl acetate , with each image corresponding to the image above in fig . 1a ( representative image of n = 3 biological replicates , scale bar = 100 nm ) . particle characterization with dynamic light scattering ( c ) and laser doppler anemometery ( d ) displayed similar hydrodynamic diameters and zeta potential respectively for all particle types . size analysis was conducted in water ( c ) and zeta potential was measured in water and in artificial cerebrospinal fluid ( acsf ) , showing the neutralization of all particle surface charge in acsf ( results are presented as mean±s . d . of n = 3 biological replicates ) ( d ) . ( e ) particle size was shown to be stable in 37 °c acsf without measurable aggregation for up to 24 h ( representative graph of n = 3 biological replicates ) .
for more information , please do not hesitate to contact dr siow kim shyong at kimshyong @ urltoken and / or dr ng pei yuen yuen22004 @ urltoken with your cv stating your qualification and experience . do include a list of publications ( if any ) , conference presentation ( if any ) or undergraduate research project report . only successful candidates will be contacted for further interview .
in conclusion , this study demonstrates that np surface properties significantly influence cellular tropism after their entry into the brain , and that engineering these surface properties provides an opportunity to control cellular distribution . we have also demonstrated that in vitro rates of association can predict in vivo cellular affinity , showing that the dynamic and complex brain environment can be modelled , at least to some extent , by a simple static in vitro system . however , it appeared that the functional outcome might not always be related solely to an absolute internalization , and that the different features of the formulations ( specificity of internalization , immunogenicity and ability to recruit specific cell types ) should also be taken into account depending on the therapeutic strategy envisioned . altogether , these results highlight the potential to optimize np - based therapeutic strategies by tuning np surface properties for enhanced delivery to certain cell types of interest and development of specific features , offering the possibility to hone the choice of the nanocarrier to each specific therapeutic molecule . tailoring the nanocarrier behaviour to each therapeutic strategy will likely improve therapeutic efficacy in target cells , and minimize treatment toxicity to off - target cells .
the therapeutic efficacy study was conducted following the exact same procedure as for the ced of dye loaded particles , using eb loaded particles . each rat received a total dose of 20 μg of eb .
) . for pla nps , a large percentage of the cell population ( 22–28 % ) internalized a significant but relatively low amount of particles , whereas the pla–hpg–cho np mfis were increased in a smaller population of cells ( 6 . 3–8 . 1 % ) , taking up a large number of particles . these observations suggest that although global uptake was higher for pla–hpg–cho nps compared to pla nps , it affected a smaller population of cells . notably , as more nps become associated with cells from 4 to 24 h , the distribution among the different cell types remained the same for all nps formulations (
cordis was the european commission’s first permanent website in 1994 . its content dates back to the 1990s and it provided web services for fp4 , fp5 , fp6 , fp7 and other ec research and innovation activities .
pla–peg nps were synthesized using a nanoprecipitation technique . polymer ( 100 mg ) was dissolved in 5 ml dmso at room temperature for 2 h . dia dye ( 0 . 2 mg ) dissolved in 2 μl of dmso was then added to the polymer solution . the polymer - dye solution was then divided into 200 μl aliquots . each 200 μl aliquot was added dropwise to 1 ml di water under strong vortex to create a np suspension . these suspensions were immediately pooled and diluted with 5 × di water . this diluted suspension was then transferred to an amicon ultra - 15 100 kda centrifugal filter unit , and centrifuged at 4 , 000 g at 4 °c for 30 min . the nps were washed twice with di water and centrifuged for another 30 min each time . after a final wash with di water , the nps were centrifuged for 1 h to achieve a final concentration of 100 mg ml −1 di water . the final np suspension was then either immediately used for in vivo or in vitro experiments , or snap - frozen at −80 °c until use .
theoretical understanding of surface chemistry will eventually become a tool to design new chemical technology including : heterogeneous ( photo ) catalysts , photovoltaics , fuel cells and much more . to reach this goal , we require new ideas and new theories of molecular interactions at interfaces . applying cutting - edge laser , molecular beam , and ultrahigh vacuum technology to design well - defined experiments that can catch molecules in the act of reacting , our group strives to provide benchmark measurements which set standards for the next generation of theoretical advance . in particular , we seek to discover the
rules
that govern the conversion of energy at interfaces . although too small to see with the naked eye and too fast to follow except with the fastest pulsed lasers , energy conversion takes place one molecule at a time and one collision at a time . by isolating these individual energy conversion events and studying them , we are building the conceptual bridge connecting our macroscopic experience of energy conversion to the molecular world .
the dynamic fluid sorption ( capillary rise ) technique is used to determine the wettability of porous systems , fibres , powders and membranes using an automated tensiometer ( krüss k100 ) ( shown in fig 5 ) . using the modified washburn equation enables to determine the surface enegry of such solids . the amount of liquid retained after measurment is also determined . furthermore this tensiometer allows for the determination of surface and interfacial tensions using the ring - or wilhelmy - plate methods . the density of liquids can be determined using archimedes principle using this instrument , this machine also allows the measurement of sedimentation rates of suspensions . we modified an ultramicro balance ( 4504 mp8 , sartorius , göttingen , germany ; accuracy = 0 . 1 μg ) to enable us to measure contact angles on single ( carbon ) fibres with diameters as low as 5 μm using the modified wilhelmy - technique ( shown in fig 6 ) .
pla–hpg–cho nps were prepared by oxidation of the vicinal diols of pla–hpg nps to aldehydes as previously described with minor modifications 24 . pla–hpg nps ( 200 μl ) at 100 mg ml −1 were incubated for 20 min on ice with 60 μl of 10 × pbs and 200 μl of 0 . 1 m naio 4 ( aq ) . the reaction was then quenched with 200 μl of 0 . 2 m na 2 so 3 ( aq ) and the nps were washed two times with di water using amicon ultracel 100 kda mwco centrifugal filter units at 12 , 200 g for 7 min each . the nps were then diluted with di water to desired concentrations for experiments .
cellular distribution of nps within tissues is critically important for their therapeutic effectiveness , as demonstrated in recent studies on the cellular distribution of particles delivered to the liver 44 or tumours 45 , 46 . here , we found that surface properties of nps are crucial in determining the cellular fate of nps after entry into the brain interstitium . peg and hpg moieties have been widely used to provide stealth properties in the systemic circulation 23 , and dense peg coating has been proposed as a means to enhance distribution in the brain interstitium 15 , suggesting that stealth properties are also required for effective brain delivery . however , in our study , those particles were the least efficiently internalized by all cell types , in healthy brains and in tumour - bearing brains , and these particles were least effective for treatment of tumours ( fig . 8b ) . the lower internalization of stealth particles might be due to decreased retention in the brain environment resulting in reduced probability of interaction with cells and the extracellular matrix , making them more prone to elimination through brain capillaries 47 or the lymphatic system ( fig . 7 ) . on the other hand , when the surface diols on pla–hpg nps were converted to aldehydes , the nps were internalized more abundantly by all cell types . in this example , the multifunctional hpg was modified to produce a bio - adhesive state , which appears to be a valuable strategy to increase cellular uptake after brain administration .
) . each np formulation was internalized more abundantly after 24 h compared to 4 h with the extent of increase being significantly influenced by the np surface properties . pla–peg and pla–hpg nps presented a 1 . 4 and 2 . 3 - fold increase , while internalization of pla–hpg–cho nps was increased even more than the pla nps ( four - and threefold increase respectively ;
( a – d ) brain slices stained for astrocytes ( gfap in white ) , showing that pla–hpg–cho nps ( red ) produced an up - regulation of gfap protein , characteristic of reactive astrocytes ( d ) , while pla , pla–peg ( red ) and pla–hpg nps ( red ) did not ( a , b , c ) at 4 h . ( e – h ; gfap in white ) after 24 h , all particles except pla–hpg nps ( red ) ( g ) induced an up - regulation of gfap proteins . ( i – l ) brain slices stained for microglia ( iba - 1 in white ) , showing that pla ( red ) and pla–hpg–cho nps ( red ) activated microglia ( i , l , microglia present mostly in amoeboid shape ) , while pla–peg ( red ) and pla–hpg nps ( red ) did not ( j and k , microglia retain their ramified state ) at 4 h . ( m – p ; iba - 1 in white ) after 24 h , all particles except pla–hpg nps ( red ) ( o ) activated microglia , with pla–hpg–cho nps ( red ) showing the largest amount of particles in the perinuclear space ( p , supplementary fig . 8 ) . for each particle type and staining , the image is representative of three slides from one animal . all images were stained with dapi ( blue ) for nuclear visualization . ( scale bar , 20 μm for zoomed in images and 50 μm for larger images ) .
a 100 μl solution of nps was lyophilized in a pre - weighed eppendorf tube to measure particle yield . dye loading was determined using a spectramax m5 plate reader ( molecular devices , sunnyvale , ca , usa ) at 456 / 590 ( nm ) . eb loading was calculated by dissolving a 10 μl aliquot of the nps in 90 μl of acetonitrile for 24 h at 37 °c . solutions were then ran through a agilent lc - ms 6120b ( agilent technologies , santa clara , ca , usa ) with standard curves to determine the loading of drug in nps . the release of eb from the different nps formulations was measured for up to 14 days . nps loaded with 2 % wt / wt drug were dispersed at 0 . 5 mg ml −1 in 1 × pbs with 0 . 5 % tween 80 , and incubated at 37 °c . at different time points ( 4 h , 8 h , 24 h , 48 h , 72 h , 5 days , 7 days and 14 days ) , the suspension was centrifuged through a 3 kda filter . filtrate was collected for hplc analysis as previously described for eb loading , and the pellet was re - suspended in the same volume of pbs for continued release .
( a ) when fluorescently labelled particles were infused in healthy fischer 344 rats via ced , they displayed similar volumes of distribution ( vd ; results are presented as mean±s . d . of n = 3 biological replicates ) . ( b ) i–iv , for all particle types , distribution in the healthy brain was homogeneous through the whole caudate ( representative image of n = 3 biological replicates , scale bar , 4 mm ) . ( c ) when infused in fischer 344 rats bearing rg2 tumours grown for 7 days , the different formulations displayed similar volumes of distribution ( vd ) , except for the pla nps that appeared to distribute more widely ( results are presented as mean±s . d . of n = 3 biological replicates ) . ( d ) i–iv , for all particle types , distribution pattern was more heterogeneous in the tumour - bearing brain compared to the healthy brain because of the presence of the tumour mass ( representative image of n = 3 biological replicates , scale bar , 4 mm ) .
nanoparticles are of long - standing interest for the treatment of neurological diseases such as glioblastoma . most past work focused on methods to introduce nanoparticles into the brain , suggesting that reaching the brain interstitium will be sufficient to ensure therapeutic efficacy . however , optimized nanoparticle design for drug delivery to the central nervous system is limited by our understanding of their cellular deposition in the brain . here , we investigated the cellular fate of poly ( lactic acid ) nanoparticles presenting different surface chemistries , after administration by convection - enhanced delivery . we demonstrate that nanoparticles with ‘stealth’ properties mostly avoid internalization by all cell types , but internalization can be enhanced by functionalization with bio - adhesive end - groups . we also show that association rates measured in cultured cells predict the extent of internalization of nanoparticles in cell populations . finally , evaluating therapeutic efficacy in an orthotopic model of glioblastoma highlights the need to balance significant uptake without inducing adverse toxicity .
pla and pla–hpg nps were synthesized using the emulsion - evaporation technique , as previously described 23 . polymer ( 100 mg ) was dissolved in 2 . 4 ml of ethyl acetate overnight . 0 . 2 mg of dia dye ( life technologies , grand island , ny , usa ) was dissolved in 600 μl dmso and added to the polymer solution . the organic phase was then added dropwise to 4 ml of di water under a strong vortex , and the mixture was sonicated for four cycles of 10 s intervals before dilution in another 10 ml of di water . the final mixture was concentrated using a rotovap for 15 min at room temperature . following evaporation , the solution was transferred to an amicon ultra - 15 100 kda centrifugal filter unit , and centrifuged at 3 , 000 g at 4 °c for 45 min . the nps were washed twice with 15 ml di water and centrifuged for 45 min each time . subsequently , the nps were re - suspended in 1 ml di water , and snap - frozen in aliquots until use .
scientific foundations have been developed for advanced ecologically acceptable technologies intended to enhance oil recovery by physico - chemical methods . a set of unique instruments and methods has been developed to study physico - chemical and rheological properties of surface and dimentional phases in the system : oil - rock - suractant solution . a novel promising conception has been developed to use the formation energy or that of injected heat carrier to generate oil - displacing fluid , gels and sols in situ . five new commercial technologies have been developed to enhance oil recovery of west siberia oil fields . the technologies passed large - scale field tests and now they are being made commercial in oil fields of west siberia .
the hydrodynamic diameter of the nps was measured by dynamic light scattering . nps ( 1 ml ; 0 . 05 mg ml −1 in di water ) was prepared and read on a malvern nano - zs ( malvern instruments , uk ) . to measure zeta potential , 750 μl of nps ( 0 . 05 mg ml −1 in di water ) were loaded into a disposable capillary cell and analysed on a malvern nano - zs . for tem imaging , 10 μl of np solution at a concentration of 10 mg ml −1 was placed on a pre - cleaned and hydrophilized cf400 - cu tem grid ( electron microscopy sciences , hatfield , pa , usa ) for 1 min . grids were stained with a 0 . 2 % uranyl acetate solution for 15 s , washed three times in di water and mounted for imaging with a tecnai t12 tem microscope ( fei , hillsboro , or , usa ) . particle stability was measured using malvern nano - zs in artificial cerebrospinal fluid ( harvard apparatus , holliston , ma , usa ) at 37 °c with a standard operating procedure taking measurements every minute .
original methods for separation , fractionation and testing hydrocarbons , heteroatomic and high - molecular oil components and metalloporphyrins , bitumens and rock organic substances etc . new data on the composition and properties of west siberia oils and those recovered from other regions of russia and cis have been obtained .
orthotopic rg2 tumours were inoculated as previously described . briefly , 3 μl containing 2 . 5 × 10 5 rg2 cells suspended in pbs were administered over 3 min using the same procedure and the same coordinates as ced . tumours were grown for 7 days before administration of particles .
) to measure cellular tropism of the different particle types . the three cell populations were identified with specific intracellular markers ( astrocytes , microglia or neurons identified by the markers glial fibrillary acidic protein ( gfap ) , iba - 1 and neun , respectively ) . for each formulation and each cell type , three pieces of information were extracted from the fluorescence - activated cell sorting data ( see methods section for detailed procedure ) : first , the percentage of cells positively internalizing nps , which was determined by measuring the population of cells shifting away from the control population (
pla–hpg copolymer was synthesized as previously described 23 . pla of 2 g and hpg at a 1 : 1 ratio were dissolved in 20 ml of dry n , n - dimethylformamide under molecular sieves overnight . 2 equivalents of n , n′ - diisopropylcarbodiimide and 20 mol % of 4 - ( dimethylamino ) pyridine were added and allowed to react for 5 days . the polymer was then precipitated with cold ether . the resulting precipitate was then re - dissolved in 10 ml of dichloromethane and precipitated with a mixture of cold ether and methanol and lyophilized for 2 days .
in this report , we studied np interaction with cells , or cellular tropism , in the context of the brain / tumour cellular microenvironment . poly ( lactic acid ) ( pla ) based nps presenting different surface chemistries were administered into the rat brain by ced . we observed that nps decorated with ‘stealth’ groups were able to avoid internalization by all cell types , including tumour cells . internalization could be restored and enhanced by functionalization with bio - adhesive end groups . we also showed that in vitro association rates measured in cultured cells could predict the extent of nps internalization by the different cell populations in vivo . finally , the evaluation of the therapeutic efficacy of the different formulations loaded with the potent cytotoxic drug epothilone b ( eb ) in an orthotopic model of glioblastoma underlined the need to balance significant uptake without inducing adverse toxicity to healthy cells . we believe that a better understanding of cellular fate for nps after brain delivery will speed the development of more effective np - based delivery systems for the treatment of brain diseases .
the zeta - potential of porous media , fibres , films , nanotubes and powders can be studied using various measuring cells by the streaming potential method ( fig 3 ) . we have two eka elekrokinetic analysers ( anton paar , austria ) and perform measurements as a function of time , ph and type and concentration of the electrolyte to assess both the stability of the measurement and the acid - base surface characteristics . the plateau region and the isoelectric point ( point of zero charge ) can be determined by ph dependent zeta - potential measurement . we can perfrom in situ measurements of samples to assess surafce modification by ( for example ) plasma treatment or protein adsorption . the machine can also be used to determine the permeability of porous materials .
nanomaterials have long been proposed as carriers to facilitate the entry and delivery of agents into the brain 4 , 5 , 6 . long circulating nanoparticles ( nps ) , such as those decorated with polyethylene glycol ( peg ) on their surface , have been proposed as a way to enhance brain penetration through the bbb . however , despite their so - called ‘stealth’ properties ( referring to their resistance to opsonization and to elimination by the reticuloendothelial system 7 ) , usually < 1 % of the injected dose gains access to the brain tissue after systemic administration 5 , 8 . transport through the nasal epithelium can be more efficient , although the small surface area and anatomical location tend to limit the value of this method 9 . local infusion directly into the brain , or convection - enhanced delivery ( ced ) 10 , can be used to slowly introduce large volumes of nps into the cerebral interstitium , allowing the nps to reside in the brain parenchyma while slowly releasing encapsulated agents over prolonged periods 11 , 12 . it has been suggested that to be efficient when administered by ced , nps need to penetrate readily through the brain pores , or be ‘brain - penetrating’ 12 , 13 , 14 . in one approach , dense peg surface coating of nps has been used to increase the distribution of particles in the brain after ced 15 , extending stealth properties to the brain interstitial space by preventing adhesive trapping in the extracellular matrix . however , even with brain - penetrating nps , varying degrees of survival benefits in animal models were achieved 11 , 12 , 16 , suggesting that other variables likely influence biological activity .
data were analysed using flowjo v . 10 . 0 . 8r1 ( flowjo , ashland , or , usa ) . after selecting for viable mononuclear cells under fsc and ssc , a population shift in the cy5 channel for each sample allowed for gating specific cell populations ( refer to supplementary fig . 1b , adapted from ngambenjawong et al . 45 ) . the fluorescence histograms of the cells gated in the dia channel were then superimposed with the histogram of the control brain cell populations , to gate the cell populations that shifted out of the control histogram . the mfi in the dia channel of this final population was then recorded . mfi values were then normalized according to dye loading using the relative fluorescence of each nps preparation obtained through a plate reader measurement . since mfi is the measurement of the fluorescence intensity of a cell population , or , to deduce what the absolute fluorescence within a cell population was , the mfi had to be multiplied by the relative percentage of the population of cells to yield the absolute fluorescence internalized by the cells :
previous studies of np delivery in the brain have evaluated the macro - level interaction of nps with tissues , by studying characteristics such as accumulation in the brain after systemic administration 17 , 18 , and volume of distribution after ced 12 , 15 , 16 , and relating these features to survival benefit . more recently , the influence of a tumour mass on the macroscopic pattern of np distribution was investigated 19 . yet , there are few studies on how surface properties of nps influence association with particular cell types once they enter the brain interstitium .
animals were anaesthetized using a mixture of ketamine ( 75 mg kg −1 ) and xylazine ( 5 mg kg −1 ) , injected intraperitoneally . rats’ heads were shaved and then placed in a stereotaxic frame . after sterilization of the scalp with alcohol and betadine , a midline scalp incision was made to expose the coronal and sagittal sutures , and a burr hole was drilled 3 mm lateral to the sagittal suture and 0 . 5 mm anterior to the bregma . a 50 μl hamilton syringe with a polyamide - tipped tubing , loaded with the nps , was inserted into the burr hole at a depth of 5 mm from the surface of the brain and left to equilibrate for 7 min before infusion . a micro - infusion pump ( world precision instruments , sarasota , fl , usa ) was used to infuse 20 μl of 50 mg ml −1 nps at a rate of 0 . 667 μl min −1 . once the infusion was finished , the syringe was left in place for another 7 min before removal of the syringe . bone wax was used to fill the burr hole and skin was stapled and cleaned . following intramuscular administration of analgesic ( meloxicam , 1 mg kg −1 ) , animals were placed in a heated cage until full recovery .