bluuebunny/crossref_metadata_2025 huggingface dataset:
Ankle Replacement versus Arthrodesis: A Comparative Gait Analysis Study
Authors: Philippe Piriou , Paul Culpan , Mark Mullins , Jean-Noel Cardon , Delphine Pozzi , Thierry Judet
Published: February 2008

Background: The improving survivorship of ankle replacements is making this an increasingly popular option in the treatment of ankle arthritis, rather than the established option of ankle fusion. The potential benefits of restoring movement, improving gait and protecting adjacent joints are persuasive arguments in favor of replacing rather than fusing the ankle joint. Methods: Gait analysis was performed before and after ankle arthroplasty on 12 patients, and compared to 12 patients with a successful ankle arthrodesis and to a healthy control group of 12 people. Results: Important differences between the arthrodesis and ankle replacement groups were demonstrated although neither restored normal movement or walking speed. Ankle arthrodesis resulted in a faster gait with a longer step length compared to replacement, although the timing of gait demonstrated greater asymmetry. The ankle replacement group had greater movement at the ankle, a symmetrical timing of gait and restored ground reaction force pattern. Conclusion: The improved timing of gait would support the observation of a reduction in limp with ankle replacement though the gait is significantly slower. Longer term results are necessary to determine whether the improved movement and force transmission persists with time and protects adjacent articulations.
Interpositional Arthroplasty of the First MTP Joint Using a Regenerative Tissue Matrix for the Treatment of Advanced Hallux Rigidus
Authors: Berlet Gregory C. , Hyer Christopher F. , Lee Thomas H. , Philbin Terrence M. , Hartman Jodi F. , Wright Michelle L.
Published: February 2008

Background: Treatment options are limited for young and active patients with hallux rigidus of the first metatarsophalangeal (MTP) joint. Soft-tissue interpositional arthroplasty is a promising alternative. Methods: The surgical technique for interpositional arthroplasty utilizing a human acellular dermal regenerative tissue matrix as a spacer is described. A retrospective review of a consecutive series of the first nine patients with Coughlin grade 3 halux rigidus who underwent this procedure is presented. Five patients were female and four were male, with a mean age of 53.3 years, a mean body mass index of 28.6, and a mean duration of symptoms of 3.1 years. Results: The mean length of followup was 12.7 months, with no reported complications or failures. The mean total AOFAS score and pain sub-score were significantly higher at the most recent followup (87.9 and 34.4, respectively) versus preoperatively (63.9 and 17.8, respectively). Conclusions: These excellent early results and lack of complications may be due to the minimal bone resection associated with the procedure. This technique does not require autograft harvesting, is bone-sparing by preserving the plantar plate, and maintains the natural intrinsics of the joint by preserving its associated tendons and the FHB insertion. The sesamoid articulation also is resurfaced. Although further followup is needed, this technique may offer the young and active patient with advanced hallux rigidus an opportunity to maintain an active lifestyle, while retaining the possibility for more surgical options should the condition progress.
Limb Salvage in Ewing's Sarcoma of the Distal Lower Extremity
Authors: Mikel San-Julian , Julio Duart , Pablo Diaz de Rada , Luis Sierrasesumaga
Published: February 2008

Background: Ewing's sarcoma (ES) of the foot and ankle is a rare condition whose treatment is controversial. There are no large series covering this issue. Some authors advise amputation as the “gold standard” treatment. The authors here prsent their experience in limb salvage of fourteen cases of ES in distal lower extremities. Methods: The clinical records of fourteen patients affected by ES in ankle or foot were reviewed. Particular attention was paid to followup, functional status, type of treatment, survivorship and histological response to treatment. Results: Straightforward amputation was employed in just 3 cases of toe location, and another case located in the calcaneum was considered unresectable. Limb salvage was achieved in most patients with tumors in tarsal and metatarsal bones, as well as distal tibia and distal fibula locations. There were no local recurrences of the tumor. All but on patient survived after a minimum follow-up of four years (4 to 22). The function at the last follow-up was excellent or good in 80% of cases of limb salvage, mainly in non-irradiated patients. Conclusions: Chemotherapy and resection with reconstruction of the foot yielded excellent results in ES cases. Survivorship of ES in distal locations seems to be better than for proximal ones. High doses of radiotherapy and amputation can be avoided in the treatment of these tumors.
Plate Fixation for Crescentic Metatarsal Osteotomy in the Treatment of Hallux Valgus: An Eight-Year Followup Study
Authors: Yuen-hon Chow Francis , Lui Tun Hing , Kwok Kin Wa , Chow Yuk Yin
Published: February 2008

Background: Distal soft tissue realignment and crescentic metatarsal osteotomy is a popular procedure in the treatment of hallux valgus. The traditional technique of screw fixation for crescentic osteotomy is technically demanding, and the inferior stability of this construct has been described. We evaluated the long-term results of a modified fixation method. Methods: Twenty-six patients (32 feet) undergoing this procedure were retrospectively reviewed. Five patients (six feet) were lost to followup. Mean age of the patients was 47 (14 to 74) years. The osteotomy was fixed with a 2.7 mm AO plate. Assessment of clinical and radiographic results was performed at a mean followup of 2.7 (1.3 to 7.2) years and 8.0 (6.1 to 12.0) years, respectively. Results: The mean American Orthopaedic Foot and Ankle Society (AOFAS) score improved from 57.9 to 90.5 at 2.7 years of mean followup, whereas the patient satisfaction rate was 96%. The intermetatarsal angle (IMA) and hallux valgus angle (HVA) improved from the mean preoperative values of 16.1 degrees and 34.2 degrees to 9.5 degrees and 16.3 degrees. At eight years of mean followup, the mean AOFAS score and patient satisfaction rate remained at 88.5% and 92%. The mean IMA and mean HVA were 9.7 degrees and 17.0 degrees. Complications included one case of hallux varus (4%) and two cases of recurrence (8%). The osteotomy achieved union in all cases. Conclusions: Dorsal plate fixation of crescentic metatarsal osteotomy is a technically easier procedure. Equally good results can be achieved when compared with screw fixation methods, and the results can be maintained long-term.
Comparison of a Novel FiberWire-Button Construct versus Metallic Screw Fixation in a Syndesmotic Injury Model
Authors: Forsythe Kevin , Freedman Kevin B. , Stover Michael D. , Patwardhan Avinash G.
Published: February 2008

Background: There is minimal experience with less rigid syndesmotic fixation devices which may approximate the normal distal tibio-fibular mechanics during healing. This study evaluates the ability of a FiberWire-button implant (Arthrex, Naples, FL) to maintain syndesmotic reduction as compared with a metallic screw. Methods: Ten matched fresh-frozen cadaveric ankle pairs with intact ligaments were tested (12.5 Nm external rotation force) to establish physiologic syndesmotic diastasis. The same force was applied to the ankles after sectioning of the syndesmotic and deltoid ligaments. Within the pairs, each limb was randomized to receive a FiberWire-button implant or a metallic screw (Synthes, Paoli, PA); the ankles were tested for syndesmotic diastasis with progressive external rotation force, from 2.5 Nm to 25 Nm (or failure). Results: There was no significant difference in diastasis amongst pairs with intact or sectioned syndesmosis ( p = 0.64 and p = 0.80, respectively). There was a significantly greater diastasis in the FiberWire-button group at all external rotation loads ( p < 0.0001). Nine of the ten pairs failed (all through fracture of the distal fibula). There were no hardware failures. The metallic screw group failed at a lower load (mean 15 Nm) compared to the FiberWire-button group (mean 18 Nm, p = 0.0004). The metallic screw group maintained syndesmotic reduction up to 5 Nm of force. Conclusions: The FiberWire-button was unable to maintain syndesmotic reduction of the ankles at any of the forces applied. The ankles fixed with the FiberWire-button demonstrated significantly greater widening of the syndesmosis compared to the screw, at all loads. Clinical Relevance: The FiberWire-button implant may not maintain adequate ankle syndesmotic reduction in the immediate post-operative period relative to a metallic screw.
Transarticular versus Extraarticular Ankle Pin Fixation: A Biomechanical Study
Authors: League Alan C. , Parks Brent G. , Oznur Ali , Schon Lew C.
Published: February 2008

Background: Transarticular pin fixation for ankle stabilization has drawbacks, including ankle joint arthrosis. An extraarticular technique could help avoid these problems. We compared stiffness under minimal dorsiflexion loading with transarticular versus extraarticular fixation. Methods: Cadaveric specimens from ten lower extremity matched pairs were randomized to receive transarticular or extraarticular fixation. For transarticular fixation, axial pins were passed retrograde through the plantar heel, calcaneus, subtalar joint, talar body, and ankle joint. For extraarticular fixation, the first pin was inserted antegrade from the anterior distal tibia to the posterolateral aspect of the calcaneus tuberosity. The second pin was inserted percutaneously antegrade from the distal medial tibial metaphysis to the dorsal navicular, passing anterior to the ankle and dorsal to the talonavicular joint. Each specimen was subjected to 1000 cycles at 5 mm/s to 100 N. After testing, the extraarticular specimens were dissected to establish the distance of the pin from the flexor hallucis longus (FHL) tendon. Results: There was no significant difference in stiffness between the transarticular and the extraarticular group (mean ± standard error of the mean) (17.93 N/mm ± 1.0 N/mm and 18.61 N/mm ± 1.07 N/mm, respectively). The lateral pin was 4.2 ± 1.4 mm (range, 2.5 to 6.0 mm) from the FHL. Conclusions: Fixation stiffness with extraarticular crossed antegrade pins was not different from that of transarticular fixation and did not disrupt the ankle or the plantar skin. Clinical Relevance: Extraarticular ankle fixation may help avoid the complications found with the joint, cartilage, and plantar skin disruption associated with transarticular fixation.
The Effect of Frontal Plane Position on First Ray Motion: Forefoot Locking Mechanism
Authors: Perez Hugo R. , Reber Leon K. , Christensen Jeffrey C.
Published: February 2008

Background: Several joints in the foot have a locking mechanism that allows the foot to function as a rigid lever. The transverse tarsal joint (talonavicular and calcaneocuboid joints) has a locking mechanism that is well understood. The purpose of the study is to determine if the first ray also has such a locking mechanism. Method: Five cadaver limbs were loaded onto a custom frame. The first metatarsal was attached to a jig that placed a force of 50 N in plantarflexion and dorsiflexion. The motion of the jig was measured with the first ray in three positions: maximally everted, neutral, and maximally inverted. No tendons were loaded to ensure that any change in motion was solely due to osseous position. Results: The average motion of the first ray for the three testing position was as follows: 7 mm in the everted position, 14 mm in the neutral position, and 18 mm in the inverted position. There was a statistically significant increase in range of motion from an everted position to a neutral position ( p = 0.003). This increase in range of motion continued when the first ray was inverted compared to neutral, but not statistically significance ( p = 0.07). Conclusion: This study demonstrates that the frontal plane position of the first ray affects the sagittal plane motion. An everted position has the least mobility, and we hypothesize that this represents a closed-packed or locked position.
Internal Architecture of the Talus
Authors: Athavale Sunita Arvind , Joshi Subhash D. , Joshi Sharda S.
Published: February 2008

Background: Ideally, bone has the external shape and internal architecture best adapted to its function. The internal architecture of the talus should reflect its functional adaptations. The purpose of this study was to evaluate the orientation of lamellae to account for its role in transmission of various forces. Method: Twenty-five pairs of dry adult human tali were sectioned in various planes and dissected grossly to study the internal architecture of the talus. Results: Two sets of lamellae were observed in the body of the talus. One set was descending from the posterior two-thirds of the lateral part of trochlear surface onto the posterior calcaneal facet of the talus. These lamellae were in the form of vertical perforated interconnected plates. The second set of trabeculae originated from medial part of trochlear surface and anterior third of the lateral part. The neck of the talus showed the continuity of sagittal plates extending from the body to the head, which was occupied by stacked curved plates extending from infero-medial to the supero-lateral part of the head. Conclusion: We identified two sets of lamellae which we believe reflect the lines of forces of weightbearing through the talus. Clinical Relevance: These findings may help in better understanding of fracture lines in the talus, which could improve internal fixation techniques, and the design of talar prostheses.
Histomorphometric Evaluation of Mechanoreceptors and Free Nerve Endings in Human Lateral Ankle Ligaments
Authors: Moraes Miguel R. B. , Cavalcante Maria Luzete C. , Leite José Alberto D. , Ferreira Francisco Valdecir , Castro Antônio Juvêncio O. , Santana Mariana G.
Published: February 2008

Introduction: Joint mechanoreceptors have been studied and most of investigators recognize the potential role of mechanoreceptors in the proprioceptive function of joint. The aim of this study was to analyze the general innervation and the possible existence of sensory receptors in the lateral ankle ligament. Methods: Lateral ankle ligaments including anterior talofibular, posterior talofibular and calcaneofibular were obtained from 24 ankles of 13 male cadavers with ages ranging from 18 to 65 (mean 41.6) years. Each ligament was divided into three parts according to the bony attachments (proximal, central, and distal segments). Histologically mechanoreceptors (Ruffini, Pacini and Golgi) and free nerve endings were identified, and classified. Histomorphometric determination and evaluation of the density of the area of the receptor was performed by the point-counting methods. Results: The anterior talofibular, posterior talofibular, and calcaneofibular ligaments were endowed with mechanoreceptor and free nerve endings. There was a significant prevalence of Pacini ( p < 0.001) compared with Ruffini and Golgi. However, there was no significant difference in the mechanoreceptors density in the different ligaments analyzed ( p > 0.05) Conclusion: Innervation of the lateral ankle ligaments was confirmed in this study, suggesting that the presence of mechanoreceptors could have clinical implication as well as relevance in the proprioceptive function. Future electrophysiological studies will be required to define the role in the proprioceptive and nociceptive system of the ankle.
Should Long-term Care Residents Be Supplemented with Vitamin D?
Authors: Lister Tracy
Published: February 2008

The Health Canada recommendation of 600 IU of vitamin D daily for those over age 70 may be inadequate to prevent deficiencies. A literature search was conducted to examine whether older people living in long-term care (LTC) facilities are at high risk for vitamin D deficiency and therefore should receive a minimum daily supplement of 800 IU. The search included the major databases; the search terms “elderly” and “vitamin D” were used. Articles primarily related to calcium were excluded. The results show that North American seniors generally consume a diet low in vitamin D and have limited sun exposure. The majority, particularly those living in LTC facilities, may have a vitamin D deficiency. Also contributing to deficiencies is an age-related decline in cutaneous production of vitamin D and altered metabolic processes responsible for converting vitamin D to its active form. In summary, research conducted in both Canada and the United States provides sufficient evidence to indicate that older people living in LTC facilities are at high risk for vitamin D deficiency and should receive a minimum daily supplement of 800 IU.
Gaining Entry-level Clinical CompetenceOutside of the Acute Care Setting
Authors: Lordly Daphne , Taper Janette
Published: February 2008

Traditionally, an emphasis has been placed on dietetic interns’ attainment of entry-level clinical competence in acute care facilities. The perceived risks and benefits of acquiring entry-level clinical competence within long-term and acute care clinical environments were examined. The study included a purposive sample of recent graduates and dietitians (n=14) involved in an integrated internship program. Study subjects participated in in-depth individual interviews. Data were thematically analyzed with the support of data management software QSR N6. Perceived risks and benefits were associated with receiving clinical training exclusively in either environment; risks in one area surfaced as benefits in the other. Themes that emerged included philosophy of care, approach to practice, working environment, depth and breadth of experience, relationships (both client and professional), practice outcomes, employment opportunities, and attitude. Entry-level clinical competence is achievable in both acute and long-term care environments; however, attention must be paid to identified risks. Interns who consider gaining clinical competence exclusively in one area can reduce risks and better position themselves for employment in either practice area by incorporating an affiliation in the other area into their internship program.
Multi‐scale responses of plant species diversity in semi‐natural buffer strips to agricultural landscapes
Authors: Ma Maohua
Published: February 2008

Question: How does agricultural land usage affect plant species diversity in semi‐natural buffer strips at multiple scales?

Location: Lepsämä River watershed, Nurmijärvi, Southern Finland.

Methods: Species diversity indicators included both richness and evenness. Plant communities in buffer strips were surveyed in 29 sampling sites. Using ArcGIS Desktop 9.0 (ArcInfo) and Fragstats 3.3 for GIS analysis, the landscape composition around each sampling site was characterized by seven parameters in square sectors at five scales: 4, 36, 100, 196, and 324ha. For each scale, Principle Component Analysis was used to examine the importance of each structural metric to diversity indicators using multiple regression and other simple analyses.

Results: For all but the smallest scales (4 ha), two structural metrics including the diversity of land cover types and percentage of arable land were positively and negatively correlated with species richness, respectively. Both metrics had the highest correlation coefficients for species richness at the second largest scale (196 ha). The density of arable field edges between the fields was the only metric that correlated with species evenness for all scales, which had highest predictive power at the second smallest scale (36 ha).

Conclusions: Species richness and evenness of buffer strips had scale‐dependent relationships to land use in agricultural ecosystems. The results of this study indicated that species richness depends on the pattern of arable land use at large scales, which may relate to the regional species pool. Meanwhile, species evenness depended on the level of field edge density at small scales, which relates to how the nearby farmland was divided by the edges (e.g. many small‐scale fields with high edge density or a few big‐scale fields with low edge density). This implies that it is important to manage the biodiversity of buffer strips within a landscape context at multiple scales.
Historical Perspective of Biosensor and Biochip Development
Authors: Newman Jeffrey D. , Turner Anthony P. F.
Published: February 2008

Biosensors, which started life largely as academic curiosities, initially had few practical applications, most of which were limited to clinical chemistry laboratories. In those early days, few could have foreseen the current situation, where there are thousands of people, in hundreds of laboratories, making up an industry, whose market value is now over $7 billion.
Overview of Biosensor and Bioarray Technologies
Authors: Lowe Christopher R.
Published: February 2008

The sections in this article are

Introduction

The Biorecognition System

Biocatalytic Systems

Affinity Binding Systems

Synthetic Biomimetic Systems

Immobilization Techniques

Transducer Technologies

Electrochemical Transducers

Optical Transducers

Acoustic Transducers

Other Transducer Technologies

Bioarray Technologies

Applications of Biosensors and Bioarrays
Protein Recognition in Biology
Authors: McCourt Paula , Nickels Joseph , Ishino Tetsuya , Chaiken Irwin
Published: February 2008

Protein recognition is pervasive in living systems. Interactions of proteins with each other and with other biomolecules occur in crowded and dynamic environments, ultimately leading to the multimolecular assemblies and networks that are recurrent components underpinning the molecular mechanisms of health and disease. Appreciating the nature and environment of protein interactions can help identify opportunities for molecular sensing in biological systems and guide the conditions needed for biomolecular sensing using biosensors and biochips.
Molecular Antibody Technologies for Biosensors and Bioanalytics
Authors: Kramer Karl , Mahlknecht Georg , Hock Bertold
Published: February 2008

Biological or biomimetic components are crucial determinants of biosensors and bioanalytical systems. Although receptors isolated from natural sources showed a high potential for analytical applications, the advance in modern methods in genetic engineering offers new routes for tailoring appropriate receptors for particular analytical tasks. Beside enzymes, hormone receptors, nucleic acids, membrane components, organelles or entire cells antibodies are frequently incorporated as biosensing elements. Due to their variable selectivity Abs are effective tools for the analysis of a wide variety of analytes ranging from low molecular weight agrochemicals (e.g., herbicides, insecticides) to complex proteins (e.g., structures of pathogenic microorganisms). The combination with up to nanomolar or even higher affinity enables the reliable trace analysis of complex sample mixtures without the need for extensive sample pretreatment or large sample volumes. In this chapter state of the art technologies are presented for Ab engineering. This includes principles for establishing Ab libraries. From these libraries selective binders can be isolated and further modified by applying the Darwinian principle of variation and selection in vitro. Experimental examples from our laboratory are given for antibody libraries, which provide a basic source for isolating suitable immunoreagents for pesticides, genetically modified organisms (GMO) and pathogens. In contrast to conventional immunoreagents, these Abs are amenable to subsequent optimization by rational design or directed molecular evolution. Furthermore, the molecular format can be modified; additional functions for the directed immobilization on sensing surfaces or integration of markers are installed by engineering fusion proteins. Finally, stability, one of the weaker points of Abs compared to biomimetics such as molecularly imprinted polymers (MIPs), can be engineered to warrant Ab functionality even under unfavorable conditions, for instance, under thermal pressure or in presence of denaturating sample components. Finally, limitations of the molecular Ab approach are indicated, which are already apparent and may be overcome by new kinds of biosensors employing straightforward production of alternatives to the Ab scaffold.
The Detection and Characterization of Ions,DNA, and Proteins Using Nanometer‐Scale Pores
Authors: Kasianowicz John J. , Henrickson Sarah E. , Lerman Jeffery C. , Misakian Martin , Panchal Rekha G. , Nguyen Tam , Gussio Rick , Halverson Kelly M. , Bavari Sina , Shenoy Devanand K. , Stanford Vincent M.
Published: February 2008

Protein ion channels are nanometer‐scale pores that are central to many biological processes, including the sensing of a wide variety of molecules. They have also demonstrated potential for use in the sensitive and selective detection of ions, the characterization of polynucleotides and toxins as well as the screening of therapeutic agents against lethal anthrax proteins. Further advances in materials engineering, theory, and signal processing are needed to enable practical applications based on biological or synthetic nanopores.
Phage‐Displayed Epitopes as Bioreceptors for Biosensors
Authors: Atias Danit , Lobel Leslie , Virta Marko , Marks Robert S.
Published: February 2008

“Phage display” is a powerful technique that allows expression of peptides or proteins on the phage surface. Exploitation of phage display technology will lead to isolation and production of a broad range of binders with predefined specificities. Emergent technologies based on phage display will benefit diagnostics by producing molecules that are otherwise unobtainable through traditional approaches. Exploitation of the advantages of phage display systems together with the ongoing development in the biosensor field would lead to revolutionary diagnostic devices. This chapter will focus on phage biology, the advantage of phage display, and its applications as epitope bioreceptors in biosensor use.
Natural Luminescent Whole‐Cell Bioreporters
Authors: Ulitzur Shimon
Published: February 2008

This chapter discusses various applications of natural luminescent bacteria, including determination of bacterial metabolic activity in food products; assays for lipase, phospholipase and esterase; long‐chain fatty acids; lipopolysaccharide; antilipogenic compounds; oil oxidation; monoamine oxidase activity and its inhibitors; antibiotic activity; serum bactericidal activity; phagocytosis; cyclic adenosine 3′, 5′‐monophosphate; oxygen transmission rates through plastic films; and early indication of marine fish spoilage. In addition, bioluminescence‐based tests for measuring various parameters of water quality will be described.
Recombinant Bacterial Reporter Systems
Authors: Belkin Shimshon
Published: February 2008

Unlike traditional biosensors, based on the unique specificity endowed by the intrinsic characteristics of biological recognition elements, the greatest advantage of whole‐cell biosensors is in the global nature of their responses. To assay the potential biological effects of a sample on a live system, one needs a live system as a part of the testing protocol. There are many good reasons to avoid the use of live animals for this purpose, and one of the most promising alternatives is the use of natural or genetically engineered microorganisms that respond to predetermined types of biological effects or classes of chemicals. While some of the specificity characterizing molecule‐based biosensors may be lost, it is more than compensated for by the fact that by using live cells we are able to detect, by very simple means, very complex series of reactions that can exist only in an intact, functioning cell. Only a sensor of this type can report on the “well‐being” of a system, on the toxicity of a sample, the genotoxicity of a chemical, or the bioavailability of a pollutant. No molecular recognition or chemical analysis can provide this type of information.

Genetically engineered whole‐cell biosensors are usually constructed from a recognition/sensing element that drives a reporting element within a live host cell. To constitute a biosensor, such cells need to be incorporated into a solid platform and coupled into a signal transduction apparatus that will detect, amplify, and translate the biological signal emitted in response to the target conditions. The potential options for selecting and combining these four building blocks—sensor, reporter, cell, and hardware—are numerous. Some of these combinations are described in this chapter.
Recombinant Aequorin‐Based Systems for Biomarker Analysis
Authors: Rowe Laura , Teasley Krystal , Dikici Emre , Qu Xiaoge , Ensor Mark , Deo Sapna , Daunert Sylvia
Published: February 2008

Detection methods utilized in the development of biosensors and biochips often require labeling strategies. Commonly employed labels include radioisotopes, enzymes, and fluorohphores. Bioluminescent proteins offer an alternative labeling option and are becoming increasingly popular because of their versatility, sensitivity, and nontoxicity. Bioluminescent labels emit light of varying colors as a method of releasing the energy that is produced by their specific chemical reactions. Aequorin is an example of one such bioluminescent protein which has been studied extensively and used in a variety of bioanalytical techniques. In this chapter, we describe the qualities of aequorin and the potential that it has as a generic label. This chapter also details several aequorin‐based immunoassays that have been developed for the monitoring of biomarkers important to both hormonal disorders and cardiovascular disease. Lastly, we discuss the progress and the pitfalls associated with developing multianalyte detection schemes and robust sensing technologies based on bioluminescent, aequorin labeling.
Electrochemical Polymerization for Preparation of Electrochemical Sensors
Authors: Weetall Howard H.
Published: February 2008

Molecular imprinted polymers (MIPs) have been prepared using a variety of monomeric substrates for the production of polymers containing imprints of small molecules. We have shown that in some cases, the MIP is not an imprinted polymer but an ion‐specific system. Preparation of MIPs using resorcinol/phenylenediamine produces, analyte‐specific electrodes that act as MIPs but appear more like organic ion exchange electrodes. These data suggest that greater care must be taken in future studies of MIPs with regard to mechanism of action.
Immobilization of Biomolecules by Electropolymerized Films
Authors: Cosnier Serge
Published: February 2008

The concepts and recent advances in procedures based on electropolymerized films for the immobilization of biological entities such as peptides, enzymes, antibodies, antigens, oligonucleotides, and microorganisms are described. The biomolecule immobilization is classified as adsorption, entrapment, covalent binding, and affinity interactions between biomolecules and films. A chronological evolution of these concepts of biosensor fabrication based on electropolymerized films is presented along with recently opened research directions.
Scanning Electrochemical Microscopy for Biomolecular Immobilization and Imaging
Authors: Szunerits Sabine
Published: February 2008

An important and challenging area of analytical chemistry is the in vivo or in vitro collection of chemical information from biological samples. Biological samples are heterogeneous and require, in numerous cases, a localized measurement of specific analytes to obtain a better and more detailed understanding of the function of the living organs. This spatial prerequisite is often coupled with a demand for high temporal resolution and minimal perturbation of the assessed microenvironment by the analytical technique. Both requirements were essential driving forces leading to the development of miniaturized analytical probes, in particular electrochemical sensors and microelectrodes. These analytical probes are used as scanning tips in scanning electrochemical microscopy (SECM). SECM is a noncontact scanning probe technique and, since its development in 1989, has proved to be a promising imaging technique for the study of biological systems. Compared to conventional optical microscopic techniques such as fluorescence spectroscopy or other near‐field scanning techniques, SECM has proved to be more efficent in locating biocatalytic reactions, in characterizing bioreactions kinetically, in determining local enzyme activity as well as in offering original approaches for protein and cell studies and is the focus of this chapter.
Modeling of Biosensor Interfaces
Authors: Lyons Michael E. G.
Published: February 2008

Approaches to the mathematical modelling of biosensor interfaces are examined. The important example of amperometric enzyme electrodes is treated in detail. In particular the solution phase transport and direct electrode kinetics of electroenzymes are described in terms of a simple model in which the steady state reaction/diffusion equation for enzyme is solved subject to physically realistic boundary conditions. The modelling of immobilized redox enzymes on self assembled monolayers is also discussed. In both of these examples limiting expressions for the reaction flux are derived and the kinetic possibilities discussed geometrically in terms of kinetic case diagrams. The development of mathematical models for the description of transport and kinetic processes involving enzymes immobilized within conducting polymer films is briefly addressed.
Conductometric Enzyme Biosensors
Authors: Dzyadevych Sergei V. , Arkhypova Valentyna N. , Soldatkin Alexey P. , El'skaya Anna V. , Martelet Claude , Jaffrezic‐Renault Nicole
Published: February 2008

The theoretical principles of the conductometric method of measurements, the potentialities for the registration of enzymatic reactions, and examples of the application are shown. Various conductometric transducers for designing biosensors are described as well as methods of immobilization of an active material on the transducer surface, schemes, and methods of measurement. Some examples of conductometric enzyme biosensors are presented; their advantages and drawbacks together with prospects of further development are discussed.
Localized Surface Plasmon Resonance (LSPR) Spectroscopy in Biosensing
Authors: Vaskevich Alexander , Rubinstein Israel
Published: February 2008

Methods based on localized surface plasmon resonance (LSPR) spectroscopy have been gaining popularity in recent years as promising transducers for label‐free biosensors. LSPR biosensing is based on the sensitivity of the localized plasmon absorbance of metal nanostructures to changes in the dielectric properties of the contacting medium. In the common scheme, a biological recognition interface is constructed on the metal nanostructure; specific binding of a bioanalyte is transduced into an optical signal, i.e., change in the plasmon absorbance (wavelength, intensity). A noted advantage of LSPR sensing is the relative simplicity of the experimental setup and measurements. In this chapter, different LSPR biosensing systems are reviewed in a comparative manner, with emphasis on basic characteristics such as system construction, refractive index sensitivity, distance sensitivity, measured parameters, and actual performance.
Chemiluminescent Optical Fiber Immunosensor
Authors: Herrmann Sebastien , Marks Robert S.
Published: February 2008

Numerous efforts are made among the scientific community to develop serological diagnostic tools that could be cheap, fast and easy to perform but with comparable sensitivity to current bulky routine laboratory tests. Chemiluminescent optical fiber immunosensors are biosensors that can fit these expectations. These devices include an ELISA‐type assay based on immobilized bioreceptors onto a surface of an optical fiber. Upon recognition of the target biomolecules, a chemiluminescent signal derived from an enzymatic reaction is captured by the fiber and transduced to a photon counting system. These immunosensors proved already to be very efficient for pathogens or tumor markers detection.
Bioluminescent Whole‐Cell Optical Fiber Sensors
Authors: Polyak Boris , Marks Robert S.
Published: February 2008

In order to assess the potential hazards inherent in contaminated soils and aquifers, it is essential that their toxicity, including genotoxicity, be properly evaluated. While several methodologies exist for rapid testing of acute toxicity, there is a lack of “user friendly” bioassays for genotoxicity (mutagenicity, etc.) monitoring. A novel approach has recently been proposed, in which genetically engineered bacteria are used as test organisms. In these bacteria, bioluminescence (
lux
) genes are fused to promoters of genes that are involved in the defense against various types of stress (i.e., DNA damage, heat shock or protein damage, heavy metal and oxidative stress). In the presence of damaging agents, therefore, when these genes are induced, the bacteria emit light in a dose‐dependent manner. This application has been adapted to field measurements by immobilizing these reporter cells on optical fibers in order to create self‐contained optrode sensors.
Applications of the Electrogenerated Luminescent Reactions in Biosensor and Biochip Developments
Authors: Marquette Christophe A. , Blum Loïc J.
Published: February 2008

This chapter presents the basic concepts and analytical applications of electrogenerated luminescence. Reactions involving luminol or ruthenium complexes are described and the technological developments necessary for their use in bioanalysis are presented.
Dual Polarization Interferometry: A Real‐Time Optical Technique for Measuring (Bio)molecular Orientation, Structure and Function at the Solid/Liquid Interface
Authors: Cross Graham H. , Freeman Neville J. , Swann Marcus J.
Published: February 2008

The measurement of proteins, their structure, and function is a crucial step in the characterization, understanding, and utilization of many biological processes. Highly sophisticated structural and functional measurement techniques have been developed over the last 40 years as separate techniques. X‐ray crystallography, nuclear magnetic resonance (NMR) and neutron reflectivity have provided structural measurements, while techniques such as surface plasmon resonance (SPR) or microcalorimetry have provided functional data. Dual polarization interferometry (DPI) is a bench‐top surface analytical technique capable of providing real‐time measurements of molecular (multi)layer dimensions. This enables both structural and functional aspects of biomolecular layers to be determined. Thus molecular immobilization, orientation, assembly, interactions, and stability can be probed, with applications, for example, in biomolecular interactions, drug discovery, sensor surface design, biofouling, and biocompatibility. While generally applicable to a wide range of physicochemical measurement, this chapter gives a few examples of biological applications, highlighting the complementarities of the structural and functional data, rather than mass based response alone, for which there are many other examples.
Grating‐Based Optical Biosensors
Authors: Erdélyi Katalin , Frutos Anthony G. , Ramsden Jeremy J. , Szendro˝ István , Voirin Guy
Published: February 2008

Introduction

The Physical Objects Measurable with Grating‐Based Optical Sensors

Particles

Thin Films

Living Cells

Applications to Areas of Human Activity

Medicine

Environment

Process Monitoring

Military

Space

Incoupling Mode Sensors

The Optical Theory of

OWLS

(Optical Waveguide Lightmode Spectroscopy)

The Structure of the Planar Grating Coupler Sensor Chip

Instrumentation

Sensor Fabrication

Immunosensors Based on

OWLS

Detection

OWLS

Assays on Living Cells

Electrochemical‐

OWLS

, Fluoro‐

OWLS

Outcoupling Mode Sensors

Chirped Grating Couplers (
CGS
) Light Pointer

Wavelength‐Interrogated Optical Sensing
(

WIOS

)

Combination of Wavelength‐Interrogated Optical Sensing and Fluorescence Detection

Array Sensors

Resonant Waveguide Grating
(

RWG

) Sensors

Referencing

Sensor Fabrication

Applications
Holographic Sensors
Authors: Lowe Christopher R.
Published: February 2008

The sections in this article are

Introduction

Holographic Transduction

Holographic Recording Materials

Analyte‐Responsive Holographic Sensors

Gases

Water and Solvents

p
H

Ions

Ionic Strength

Enzymes and Enzymatic Reactions

Metabolite Sensors

Glucose

Lactate

Bacteria
Love Wave Biosensors
Authors: Melzak Kathryn A. , Gizeli Electra
Published: February 2008

Love wave sensors are acoustic devices that employ Love waves, propagating shear‐horizontal acoustic waves that are confined to the surface region of a substrate by a waveguide with an intrinsic shear acoustic speed lower than that of the substrate. In common with many other acoustic sensors, the principle of measurement is that the propagation of the acoustic wave through the solid medium of the sensor is affected by changes in the adjacent medium that contains the analyte of interest. Characterizing the way this interaction is analyzed and used in the process of extracting information about the sample, is a problem of several parts. The fundamental physical questions are about the manner in which the wave propagates and the manner in which this propagation is affected by changes in the medium adjacent to the sensor; an additional challenge for biosensors is to quantify these changes by using well‐characterized chemical and biological samples. Additional practical considerations involve the design of the Love wave device, the measurement of the wave propagation, and the development of a biorecognition layer specific to the analyte of interest. In general, on the basis of the system's sensitivity, detection limit, and applicability to biological sensing, it appears that the Love wave biosensor can become a competitive system to currently available optical and acoustic instruments.
Magnetic Acoustic Resonator Sensor (MARS)
Authors: Araya‐Kleinsteuber Bernardita , Stevenson Adrian C. , Lowe Christopher R.
Published: February 2008

This section presents a novel technique that could be considered as the next generation of quartz crystal microbalance. The magnetic acoustic resonator sensor (MARS), uses a planar spiral coil to vibrate a single quartz crystal from 6 MHz to 1.1 GHz to obtain multifrequency acoustic spectra. The use of a noncontacting coil, instead of electrodes, allows the selection of harmonics at various frequencies, which in turn allows the control of the evanescent field at the sensor surface, so the biophysical properties of the solid–liquid interface can be investigated in greater detail.
Thermal Biosensor and Microbiosensor Techniques
Authors: Xie Bin , Danielsson Bengt
Published: February 2008

This chapter describes principles and features of thermal biosensors and microbiosensors and includes a discussion of different thermal transducers. A number of instrumental concepts are described in detail from larger flow injection instruments to miniaturized devices and chip designs with thermal arrays. A thermal–electrochemical hybrid sensor is also presented. The chapter contains many descriptions of actual assays from different fields, such as process and in vivo monitoring, multianalyte determination, operation in organic solvents, and environmental analysis.
Microcalorimetry and Related Techniques
Authors: Cooper Alan
Published: February 2008

Direct determination of heat effects from biomolecular processes has significant potential for noninvasive biosensor and biomolecular analysis procedures requiring no additional labeling or attachment procedures. This chapter describes current instrumental techniques in isothermal titration (ITC), differential scanning (DSC), pressure perturbation (PPC) and photocalorimetry, together with examples of some relevant applications. Some developments and associated problems in calorimeter‐on‐a‐chip and related devices are discussed.
Polymer‐Based Microsystem Techniques
Authors: Schuenemann Matthias , Harvey Erol C.
Published: February 2008

One of the greatest challenges in developing low‐cost, disposable polymer microfluidic biosensors is to select a set of manufacturing processes that can be readily scaled in volume for each of the development stages. For prototyping and small to medium series production, laser‐cutting channels and structures into thin polymer layers proved to be a flexible and versatile technology, whereas for later development stages leading up to preclinical trials, replication techniques such as microinjection molding and hot embossing are more suitable to achieve the required production volumes. This chapter discusses manufacturing concepts, material selection, microfabrication, surface modification, and bonding techniques for highly miniaturized polymer biosensors and bioanalytical systems.
Microelectrochemical Systems
Authors: Evans Stuart A. G. , Murphy Lindy J.
Published: February 2008

The small physical size and low detection limits achievable with microelectrodes make them appealing for a diverse range of applications including analytical chemistry and biochemistry. This review describes typical methods of microelectrode fabrication and a summary of their application in the fields of sensors, biosensors, and scanning electrochemical microscopy.
Chemical and Biological Field‐Effect Sensors for Liquids—A Status Report
Authors: Poghossian Arshak , Schöning Michael J.
Published: February 2008

Basic concepts, functional principles, and current trends in research and development of semiconductor‐based field‐effect chemical sensors and biosensors are described. The presented sensor devices summarize the following: ISFETs (ion‐sensitive field‐effect transistor), capacitive EIS (electrolyte‐insulator‐semiconductor) sensors and LAPS (light‐addressable potentiometric sensor) structures.
Nanobiolithography of Biochips
Authors: Gheber Levi A.
Published: February 2008

The maturation of arrayed biosensors (mainly DNA microarrays, known as
DNA chips
) has demonstrated the power of the parallel approach to sensing in general and biosensing in particular. The ability to ask thousands of questions and obtain simultaneous answers enables high‐throughput screening of potential drugs, diagnosis of genetically derived disorders, and basic genome research. The promise of the biochip, though, goes much further and farther: online monitoring of drinking water and food quality, point‐of‐care diagnosis, biodefense, and other futuristic applications. To reach there, though, there is a need to almost completely transform the existing technology, which at present is highly localized to large research laboratories, big pharmaceutical companies, or advanced medical centers.

Several aspects must be considered simultaneously (a step‐by‐step improvement of existing technology is likely to fail): the “spot” size needs to be reduced by several orders of magnitude, reporting and reading systems must be integrated, sample preparation and handling subsystems should also be integrated, the devices need to be increasingly autonomous and have communication abilities, and label‐free detection methods need to be developed to enable on‐line operation.

One possible avenue, nanobiolithography, has gained much attention during the past years. We review the problems and possible ways to solve them, using state‐of‐the‐art nanobiolithography techniques.
Protein Chips and Detection Tools
Authors: Yokoyama Kenji , Hiratsuka Atsunori , Kinoshita Hideki , Usui Keisuke , Suzuki Yoshio
Published: February 2008

Protein chips and detection tools for proteins are described. A protein microarray as a typical detection chip for protein analysis is briefly introduced. Two‐dimensional electrophoresis systems are introduced. Authors have developed two kinds of 2D electrophoresis systems, for instance, on‐chip 2D electrophoresis system integrating isoelectric focusing and SDS‐PAGE and a high‐throughput fully automated 2D electrophoresis system. A novel fluorescent dye for staining proteins in a 2D electrophoresis gel is also described.