Patent Publication Number: US-2023146392-A1

Title: Low-friction coatings for syringes and related methods

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 63/263,851, filed on Nov. 10, 2021 and titled, “Low-Frication Coatings for Syringes and Related Methods,” which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of medical devices. More specifically, the present disclosure relates to a syringe having a syringe plunger and a syringe plunger tip. Even more specifically, the present disclosure relates to low-friction coatings for syringes tips and methods related thereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments disclosed herein will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. These drawings depict only typical embodiments, which will be described with additional specificity and detail through use of the accompanying drawings, in which: 
         FIG.  1 A  illustrates a perspective view of an embodiment of a syringe assembly according to the present disclosure. 
         FIG.  1 B  illustrates a side cross-sectional view of the syringe assembly of  FIG.  1 A . 
         FIG.  2    illustrates a side cross-sectional view of an embodiment of a syringe plunger tip according to an embodiment of the present disclosure. 
         FIG.  3    illustrates a side cross-sectional view of an embodiment of a syringe plunger tip according to an embodiment of the present disclosure. 
         FIG.  4    illustrates a side cross-sectional view of an embodiment of a syringe plunger tip according to an embodiment of the present disclosure. 
         FIG.  5 A  illustrates a side cross-sectional view of a syringe plunger tip according to an embodiment of the present disclosure. 
         FIG.  5 B  illustrates a side cross-sectional view of a syringe plunger tip according to an embodiment of the present disclosure. 
         FIG.  6    illustrates a side cross-sectional view of an embodiment of a syringe assembly according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Syringes may be configured to displace fluid via displacement of a plunger tip within a syringe barrel, as described below. Smooth or even displacement of the plunger tip may be beneficial for controlling the rate at which material is dispensed from a syringe. However, compressive forces acting between the syringe tip and an inside surface of a syringe barrel may result in frictional forces that resist displacement of the plunger tip within the syringe barrel. Differences between static and dynamic frictional forces may make it difficult to move a syringe plunger by a small amount, as the plunger may tend to “stick” in a stationary position, then “jump” or suddenly slide quickly as it is displaced. As detailed herein, reduction of friction may facilitate smooth operation of a syringe. 
     Low-friction coatings for syringes, as well as syringes and syringe components having such coatings, are disclosed herein. In some embodiments, a coating is disposed on at least a portion of an external surface of a syringe plunger tip. The coating may comprise a material that is different than the material of the plunger tip. The material properties of the coating and the plunger tip may differ in at least one material property, as further described below. For example, the coating may comprise a material with a lower coefficient of friction when in contact with the interior surface of a syringe barrel than the material of the plunger tip. Further, in some embodiments, the plunger tip may compress to provide a sealing force between the plunger tip and coating and the interior surface of a syringe barrel. 
     In some embodiments, the coating may be disposed on one or more portions of the external surface of the plunger tip and may further be substantially restricted to said portions. For example, a plunger tip may comprise an annular wall and may include one or more ridges extending radially from the annular wall, and the coating may be disposed on all or part of the external surface of one or more of the ridges. 
     In some embodiments, it may be desirable to separate or isolate the material of a plunger tip and/or syringe barrel from the contents of the syringe reservoir. In some such instances, a coating may configured to prevent or minimize contact and/or chemical leaching of materials between a plunger tip and/or syringe barrel and material within a syringe reservoir. For example, in some embodiments it may be desirable to isolate a silicone plunger tip and, for example, a substance containing polyvinyl alcohol (PVA) within the syringe barrel. In another example, a coating may be configured to prevent contact between a silicone plunger tip and a substance containing gelatin foam (examples include SurgiFoam™ from Ethicon or Gelfoam™ from Pfizer) within the syringe barrel. In some instances, silicone plunger tips may be incompatible with use of PVA or gelatin foam. In some instances, for example, silicone material from the plunger tip or silicone lubrication within the syringe barrel may tend to coat or otherwise adhere to the PVA or gelatin foam if these components are in contact. This may, in turn, interfere with hydration of PVA or gelatin foam particles thus causing them to agglomerate. Thus, the coatings provided herein may be impermeable or demonstrate low permeability to silicone to prevent such contamination. As used herein, “silicone” refers broadly to polymeric compounds that consist of silicon-oxygen backbone chains ( . . . —Si—O—Si—O— . . . ) n  (e.g., compounds containing one or more siloxane groups). 
     In some embodiments, a coating is disposed on at least a portion of an interior surface of a syringe barrel. The material properties of the materials used for the coating and the interior surface may differ in certain respects. For example, the coating may comprise a material that provides a lower coefficient of friction between the plunger tip and the coating than the coefficient of friction between the plunger tip and the material of the interior surface without the coating. 
     Certain plunger tips within the scope of this disclosure include one or more sealing rings disposed along an annular wall of the plunger tip. One or more of these sealing rings may be configured to compress and/or deform against an inside surface of the syringe barrel, creating a pressure seal. Thus, the sealing rings may be configured to function as o-rings or sealing portions. As discussed herein, embodiments with one, two, three, four, five, six, or more sealing rings on a single plunger tip are within the scope of this disclosure. Further, one or more annular recesses may be disposed adjacent at least one of the sealing rings. Annular recesses may be configured to provide space to accommodate deformation of the sealing ring to enhance sealing. 
     The compression, forces, and interaction between the sealing rings and the inside surface of the syringe barrel may be such that a significant proportion of the frictional engagement between the plunger tip and the syringe barrel is at the points of contact between the sealing rings and the syringe barrel. In some instances, a low friction coating may be applied only to the sealing rings, or only to a radially outward-most portion of one or more sealing rings of a plunger tip. 
     Embodiments within the scope of this disclosure include embodiments wherein a coating is disposed on a portion of an inside surface of a barrel and no coating is disposed on the syringe tip, embodiments wherein a coating is disposed on the syringe tip and no coating is disposed on the barrel, and embodiments wherein both the syringe tip and the barrel comprise coatings. In embodiments wherein both the syringe barrel and plunger tip comprise a coating the coefficient of friction between the two coatings may be configured to facilitate smooth operation of the syringe. 
     In some embodiments, a coating comprises one or more polymeric materials. Coatings within the scope of this disclosure may comprise polymeric materials including, but not limited to, polyolefins, polyethylene, perfluoropolyether (PFPE), perfluoropolyalkylether (PFAE), or a thermoplastic elastomer. In some embodiments, the coating may comprise a polyethylene including, but not limited to, linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), expanded polytetrafluoroethylene (ePTFE), polytetrafluoroethylene (PTFE), or a composite of any of these materials. In some embodiments, the coating material may be adhered to, e.g, covalently bonded to, the material of the surface on which it is disposed. Such coatings may facilitate, for example, controlled sliding of a syringe plunger tip along the length of an interior surface of a syringe barrel. Additionally or alternatively, such coatings may prevent a substance loaded within a syringe barrel from being contaminated by, or contaminating, syringe components. 
     Methods for manufacturing a syringe assembly including coatings for components thereof are also provided by the present disclosure. In some embodiments, the methods comprise applying a coating to a syringe plunger tip, wherein the plunger tip comprises a first material and the coating comprises a second material, and wherein at least one material property of the first material differs from at least one material property of the second material. The coating material may be deposited onto the external surface of the plunger tip through a number of different processes, including, for example, dip coating, sputtering, spray coating, or spin coating. In some embodiments, the method may further comprise loading a substance comprising PVA or gelatin foam into a reservoir defined by an interior surface of a syringe barrel, wherein said reservoir is configured to receive the plunger tip. In some embodiments, a method of manufacturing a syringe can comprise depositing a coating onto a portion of the interior surface of a syringe barrel. 
     In some embodiments, the coatings described herein may comprise a material that isolates, for example by physical and/or chemical separation, a syringe component from a substance loaded into a syringe barrel. The component may be a plunger tip and/or the interior surface of the barrel itself. Again, this isolation may be due to prevention of physical contact between the component and the substance. Further, the coating may be substantially impermeable to migration of chemical components across the coating. 
     It will be readily understood with the aid of the present disclosure that the components of the embodiments, as generally described and illustrated in the figures herein could be arranged and designed in a variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
     The phrases “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to or in communication with each other even though they are not in direct contact with each other. For example, two components may be coupled to or in communication with each other through an intermediate component. 
     The terms “proximal” and “distal” refer to opposite ends of a medical device. As used herein, the proximal end of a medical device is the end nearest a practitioner during use, while the distal end is the opposite end. For example, the proximal end of a standard syringe refers to the end associated with the plunger handle while the distal end corresponds to the outlet. 
     The term “material property” refers to any property or characteristic of a substance comprising components described herein. For example, material properties may include, but are not limited to, a material&#39;s chemical make-up (e.g., materials that contain silicon versus those that do not), a material&#39;s coefficient of friction as measured with another material or surface, a material&#39;s permeability, and other physical, chemical, mechanical, structural, electrical or other properties. 
       FIGS.  1 A and  1 B  are, respectively, a perspective view and a cross-sectional view of one embodiment of a syringe assembly  100  according to the present disclosure. In the illustrated embodiment, the syringe assembly  100  extends between a proximal end  102  and a distal end  104 . Further, the illustrated syringe assembly  100  includes a syringe barrel  110  having an interior surface  112 . The interior surface  112  may define a reservoir  114 . The reservoir  114  defined by interior surface  112  may be any suitable size and shape, e.g., for receiving a syringe plunger (such as plunger  120  discussed below). In one embodiment, the reservoir  114  may be generally cylindrical in shape. The reservoir  114  defined by interior surface  112  may be configured to receive a substance  15 . Syringe barrel  110  may further include a tip  116  having an opening  117  in communication with the reservoir for receiving or expelling the substance  15  from the reservoir  114 . In the illustrated embodiment, the tip  116  and opening  117  are disposed adjacent the distal end of the syringe barrel. 
     Syringe barrel  110  may include an additional opening  118  located, for example, at a proximal end of the barrel, for receiving a plunger  120 , which may be disposed or partially disposed within the syringe barrel  110 . The plunger  120  may comprise an elongate handle portion  122  having both a proximal end  124  and a distal end  126 . The plunger  120  may typically have a length that is at least as long as a length of the syringe barrel  110 . Accordingly, the proximal end  124  of the plunger may extend out from the barrel  110  when the plunger is disposed within the barrel  110 . The plunger  120  may otherwise have any size and shape that is suitable for being disposed within the syringe barrel  110 . 
     A plunger tip  130  may be coupled to handle portion  122 . The plunger tip  130  may be a tip that is integrally molded with handle portion  122  or a tip that is attached separately. In one embodiment, the plunger tip  130  may be coupled to the distal end  126  of handle portion  122 . The plunger tip  130  may comprise an external surface  134 . In certain embodiments, the plunger tip  130  may be configured to contact at least a portion of the interior surface  112  of barrel  110 . Accordingly, the plunger tip  130  may have a size and shape that is complimentary to the size and shape of the reservoir  114  defined by interior surface  112 . For example, the plunger tip  130  may be generally cylindrical in shape such that a portion of its external surface  134  may have a circumference that is the same or similar in size to a circumference of the interior surface  112  of a barrel  110  that is also cylindrical in shape. 
     Furthermore, the plunger tip  130  may be sized such that, when disposed within the syringe barrel  110 , the syringe barrel  110  radially constrains and/or compresses the plunger tip  130 . The plunger tip  130  may be comprised of an elastomeric material that, due to the compression, provides a radially outward-oriented force on the interior surface  112  of the syringe barrel  110 . Compression of the plunger tip  130  may thus result in a radial outward force that tends to seal the plunger tip  130  against the interior surface  112  of the syringe barrel  110 . 
     In some embodiments, a coating  140  may be disposed on the external surface  134  of the plunger tip  130 . In certain embodiments, coating  140  may be disposed on the entire external surface  134  of plunger tip  130 . In other embodiments, coating  140  may be disposed on only a limited portion of the external surface  134  of the plunger tip  130 . In certain embodiments, the coating  140  may be disposed on the external surface  134  such that it is positioned between at least a portion of the external surface  134  of the plunger tip  130  and the interior surface  112  of barrel  110 . The coating  140  may be configured to reduce the coefficient of friction between the plunger tip  130  and the interior surface  112  of the syringe barrel  110 . Stated another way, the coefficient of friction between the material of the coating  140  and the material of the syringe barrel  110  may be less than the coefficient of friction between the material of the plunger tip  130  and the material of the syringe barrel  110 . The coating  140  may be disposed along portions of the plunger tip  130  that would otherwise contact the interior surface  112  of the syringe barrel  110 . 
     Additionally, in some embodiments, the coating  140  may further be disposed on the external surface  134  of plunger tip  130  in such a way that the coating  140  may provide a barrier between the external surface  134  and a substance  15  loaded in the reservoir  114  such that there is no physical contact between the external surface  134  and substance  15 . 
       FIGS.  2 - 8    are a series of views of various embodiments of a syringe assembly and components thereof that can, in certain respects, resemble a syringe assembly and components thereof described in connection with  FIGS.  1 A and  1 B . It will be appreciated that all the illustrated embodiments may have analogous features. Accordingly, like features are designated with like reference numerals, with the leading digits incremented, e.g., to “2,” “3,” or “4.” For instance, the coating is designated as “ 140 ” in  FIGS.  1 A and  1 B , and analogous coatings are designated as “ 240 ” in  FIG.  2   , “ 340 ” in  FIG.  3   , and so on. Relevant disclosure set forth above regarding similarly identified features thus may not be repeated hereafter. Moreover, specific features of the syringe assembly and related components (e.g., the coating) shown in  FIGS.  1 A and  1 B  may not be shown or identified by a reference numeral in the drawings or specifically discussed in the written description that follows. However, such features may clearly be the same, or substantially the same, as features depicted in other embodiments and/or described with respect to such embodiments. Accordingly, the relevant descriptions of such features apply equally to the features of the syringe assemblies and components thereof of  FIGS.  2 - 8   . Any suitable combination of the features, and variations of the same, described with respect to the syringe assembly and components thereof illustrated in  FIGS.  1 A and  1 B  can be employed with the syringe assemblies and components thereof of  FIGS.  2 - 8   , and vice versa. This pattern of disclosure applies equally to further embodiments depicted in subsequent figures and described hereafter. 
     Referring to  FIG.  2   , a cross-sectional side view of a component of a syringe assembly is shown, i.e., a plunger tip  230  having an external surface  234 . A coating  240  may be disposed on at least a portion of external surface  234 . Plunger tip  230  may include an annular wall  232  and a top portion  236  coupled to the annular wall  232 . When the plunger tip  230  is part of a syringe assembly (such as shown in  FIGS.  1 A and  1 B ), the annular wall  232  may be in contact with an interior surface of a syringe barrel ( 112  of  FIG.  1 B ). The coating  240  may be disposed to cover all or portions of annular wall  232  and/or top portion  236 . Annular wall  232  and top portion  236  may comprise any suitable size and shape for a plunger tip. For example, annular wall  232  may comprise a generally cylindrical or circular shape, and top portion  236  may be, for example, flat or may extend outward from or inward toward annular wall  232 . 
     The annular wall  232  may include one or more ridges or sealing rings protruding from its external surface  234 . The one or more ridges may have a generally rounded shape and may protrude outward, for example, from external surface  234  of annular wall  232 . In certain embodiments, annular wall  232  may have a generally circular shape, and the one or more ridges may extend around an outer circumference of annular wall  232 . As shown, the plunger tip  230  can comprise a proximal ridge  238  disposed around at least a portion of a circumference of the plunger tip  230  at or adjacent a proximal end of the plunger tip  230 . The plunger tip  230  can also comprise a distal ridge  242  disposed around at least a portion of the circumference of the plunger tip  230  at or adjacent the distal end of the plunger tip  230 . Stated another way, the distal ridge  242  may be disposed distal of the proximal ridge  238 . 
     As also discussed below, the coating  240  may coupled to the plunger tip  230  through adhesion of the coating material to the plunger tip material. That is, the coating  240  may be applied to the plunger tip  230  in a manner in which the coating  240  is coupled or adheres to the plunger tip  230 . Additionally or alternatively, the coating  240  and plunger tip  230  may be coupled through use of secondary adhesive materials and/or mechanical fasters or features. For example, the plunger tip  230  and coating  240  may comprise interlocking mechanical features. In the embodiment of  FIG.  2   , the plunger tip  230  comprises an annular groove or recess  235  that interlocks with an annular ring or protrusion  245  on the coating  240 . Other interlocking features are also within the scope of this disclosure. Geometric features with mating portions (such as  235  and  245 ) may be configured to support or reinforce the coupling of a coating  240  to a plunger tip  230 , including in embodiments wherein the coating  240  is configured to adhere to the plunger tip  230 . 
     Referring to  FIG.  3   , a cross-sectional side view of a coated plunger tip  330  according to another embodiment is shown. Plunger tip  330  may comprise an annular wall  332 , a top portion  336 , and an external surface  334 . As shown, the plunger tip  330  can comprise a proximal ridge  338  and a distal ridge  342  each disposed around at least a portion of the circumference of the plunger tip  330 . The plunger tip  330  can further comprise a medial ridge  344  disposed around at least a portion of the circumference of the plunger tip  330  at a position between each of the proximal ridge  338  and the distal ridge  342 . In certain embodiments, the plunger tip  330  may comprise one ridge, two ridges, three ridges, four ridges, five ridges, six ridges, or another suitable number of ridges. As illustrated, coating  340  may conform to the shape of the external surface of these features. 
     As also noted above, one or more the ridges  342 ,  344 ,  338  may be configured to be compressed or otherwise deformed to facilitate sealing of the plunger tip  330  against an interior surface of a syringe barrel ( 112  of  FIG.  1 B ). Annular recesses may be disposed adjacent one or more the ridges  342 ,  344 ,  338  and may be configured to accommodate deformation of the ridge. Thus, annular recesses may work in combination with the ridges  342 ,  344 ,  338  to facilitate sealing. Furthermore, as shown in  FIG.  3   , embodiments wherein a coating  340  follows the contours of these features, the coating may be configured to allow or accommodate deformation of the ridges  342 ,  344 ,  338  into the annular recesses. Stated another one, the contour and thickness of the coating  340  may allow the ridges  342 ,  344 ,  338  to deform in a functionally equivalent or similar way to the deformation of the ridges of an uncoated plunger tip. 
     In some embodiments, a coating may be disposed mainly on certain parts of annular wall. For example, a coating may be disposed on one or more of the ridges. This may be useful where the plunger tip is shaped so that certain ridges interact with and/or generate a significant portion of the friction associated with interaction between the plunger tip and the interior surface of the syringe barrel.  FIG.  4    shows a cross-sectional side view of a coated plunger tip  430  according to an embodiment in which a coating  440  is disposed on the top portion  436  and includes the distal ridge  442  and the medial ridge  444 , but not the proximal ridge  438 . 
     In accordance with the foregoing, in some embodiments a coating may be further restricted to parts of the annular wall or features that contact the interior surface of the syringe barrel.  FIG.  5 A  shows a cross-sectional side view of a coated plunger tip  530  according to an embodiment in which a coating  540  is disposed mainly on the top portion  536  and on the distal ridge  542  and the medial ridge  544 , but is absent from the proximal ridge  538  and other parts of the annular wall  532 . 
     Still further, in some embodiments within the scope of this disclosure, the coating may only be disposed on one or more ridges, and absent from other portions of the plunger tip. For example,  FIG.  5 B  illustrates an example of a plunger tip  530 ′ with a coating  540 ′ disposed on annular ridges  544 ′ and  542 ′ wherein the remainder of the plunger tip  530 ′ is uncoated. In some embodiments the coating  540 ′ may only be disposed on a portion of the ridges  542 ′,  544 ′, including embodiments wherein the coating is only disposed on a radially outward-most portion of the ridges  542 ′,  544 ′. For example, as shown in  FIG.  5 B , the coating may only be disposed on a top surface of the ridges  542 ′,  544 ′, meaning the radially outward-most portion of the ridges  542 ′,  544 ′. Embodiments wherein the coating  540 ′ also extends down the sides of the ridges (for example as shown in ridge  544  of  FIG.  5 A ) are also within the scope of this disclosure. The coating may be disposed on portions of the annular wall  532 ′ that generate a substantial amount of the friction between the plunger tip  530 ′ and the interior surface of a syringe barrel ( 112  of  FIG.  1 B ). 
     As mentioned above, syringe tips with any number of ridges are within the scope of this disclosure. Coatings of any of the types described above may be used in connection with any number of ridges. For example, coatings positioned on the tops of the ridges, such as shown in  FIG.  5 B  with coating  540 ′, may be disposed on any number of ridges, including embodiments wherein any subset of the total ridges on the plunger tip include coatings. Furthermore, combinations, such as configurations where certain ridges are coated only on the tops of the ridges (such as shown in  FIG.  5 B ) and certain ridges are coated on the top and sides of the ridges (such as shown on ridge  544  of  FIG.  5 A ) are likewise within the scope of this disclosure. Additionally, combinations wherein certain ridges are coated and certain adjacent annular recesses (such as shown between ridges  442  and  444  of  FIG.  4   ) are also within the scope of this disclosure. In other words, any arrangement of coating for any specific ridge, can be in the form of any of the examples shown herein, in connection or combination with any other arrangement of coating shown herein. 
     The syringe barrel of any of the embodiments of the present disclosure may comprise any size, shape and material known in the art to be suitable for such syringe components. Accordingly, the syringe barrel may have a cylindrical shape and may be configured to have a plunger disposed within an interior reservoir of the syringe barrel. In some embodiments, the syringe barrel may comprise a plastic or polymeric material. 
     The handle portion of the plunger of any of the embodiments of the present disclosure may comprise any size, shape and material known in the art to be suitable for such syringe components. The handle portion may comprise a stiff or rigid material that can transfer a force exerted upon it to a plunger tip to which it is coupled or attached to move the plunger tip within the syringe barrel. In some embodiments, the handle portion may comprise a plastic or polymeric material. The handle portion may be longer in its length than in its width or diameter such that it can extend through the entire length of a syringe barrel. Such an elongate design allows the handle portion to be used to move a plunger tip throughout the entire length of a syringe barrel. 
     The plunger tip may be a tip that is integrally molded to the plunger handle portion or a tip that is attached separately. The plunger tip may be of any design that is of a suitable size and shape for being disposed or otherwise inserted into a syringe barrel such that the plunger tip is in mechanical communication with an interior surface of the syringe barrel. For example, the plunger tip may have a generally cylindrical or circular shape, and the syringe barrel may have a generally cylindrical or circular shape such that they are in contact with each other along all or a portion of an outer circumference of the plunger tip and an inner circumference of the syringe barrel. Further, the plunger tip may comprise an entirely solid structure or may comprise a structure that is hollow or includes a cavity. 
     In some embodiments, the plunger tip may comprise a material that is resiliently compressive such that the plunger tip may exert a force against the interior surface of the syringe barrel. Thus, the plunger tip may be capable of compressing and deforming against the interior surface of the syringe barrel when disposed within the interior of the syringe barrel. The force exerted by the resiliently compressive material deforming against the interior surface may serve to hold the plunger tip in position within the syringe barrel until displaced by a practitioner. The force may also be a sealing force that prevents any leakage or transmission past the plunger tip of a substance loaded within a reservoir defined by an interior surface of the syringe barrel. In some embodiments, the plunger tip may comprise a thermoplastic elastomer. In some embodiments, the plunger tip may comprise a material containing silicon, such as, for example, silicone or silicone rubber. 
     Any of the components of the syringes disclosed herein (e.g., the barrel, plunger, handle portion and/or plunger tip) may comprise any polymeric material, such as, for example, acrylonitrile-butadiene-styrene polymer, polycarbonate, polypropylene, or cyclo-olefin polymer or copolymer. In some embodiments, any of the syringe components disclosed herein, including the plunger tip, may comprise a material that contains silicon, such as, for example, silicone or silicone rubber. Alternatively, any of the syringe components disclosed herein may comprise a silicon-free material. Additionally, any of the syringe components disclosed herein may be lubricated with a silicon-free lubricant. 
     The coating according to the present disclosure may comprise a material that is deposited onto the plunger tip by, for example, dip coating, sputtering, spray coating, or spin coating techniques. In some embodiments, electrospraying or electrospinning techniques may be used. In some embodiments, the coating may be cross-linked or otherwise bonded to the material of the plunger tip. In some embodiments, the coating may have a thickness from about 0.1 μm to about 50 μm, or from about 0.5 μm to about 1.5 μm. 
     The coating according to the present disclosure may comprise a different material than that of the plunger tip. In some embodiments, the material properties of the materials used for the coating and the plunger tip may differ in certain respects. Accordingly, the coating may comprise any suitable material including those that provide a reduced-friction interface, as compared to the plunger tip material, between a plunger tip and an interior surface of a syringe barrel. Thus, the coating may comprise a material that provides a lower coefficient of friction between the coating and the interior surface of the syringe barrel than the coefficient of friction between the plunger tip and the interior surface of the syringe barrel. 
     In some embodiments, the coatings of the present disclosure may also comprise a material that isolates a plunger tip from a substance loaded into a reservoir defined by an interior surface of a syringe barrel by preventing physical contact between the plunger tip and the substance. Thus, the coating may comprise a material that is impermeable to either the substance or to a material contained in the plunger tip. For example, the coating may prevent a silicon-containing material, such as silicone, of a plunger tip from contaminating a substance comprising PVA or gelatin foam loaded in the syringe. 
     The coating material may be formulated so as to be capable of adhering or bonding to the plunger tip material. In some embodiments, the coating may comprise one or more polymeric materials. For example, the coating may comprise polyolefins, polyethylene, perfluoropolyether (PFPE), or perfluoropolyalkylether (PFAE). Polyethylene coatings may comprise LLDPE, HDPE, ePTFE, PTFE, or a composite of any of these materials. In certain embodiments, the plunger tip may comprise silicone and the coating disposed on the plunger tip may comprise LLDPE, HDPE, ePTFE, PTFE, or a composite of any of these materials. 
     Methods for manufacturing a syringe assembly are also provided by the present disclosure. Referring again to  FIGS.  1 A and  1 B , one embodiment of such a method may comprise applying a coating  140  to a plunger tip  130 . Such applying may comprise depositing a material onto at least a portion of any external surface  134  of the plunger tip  130  such that the deposited material forms the coating  140 . For example, the material may be deposited by electrospinning or rotational spinning the material onto the external surface  134  of plunger tip  130 . In some embodiments, LLDPE, HDPE, PTFE, or other polymers may be electrospun or rotational spun onto a plunger tip  130  comprising, for example, silicone. 
     Methods for isolating a substance loaded in a syringe from one or more syringe components are also provided by the present disclosure. Such methods may prevent a syringe component from contaminating or otherwise contacting or interfering with the substance, and vice versa. Referring to  FIGS.  1 A and  1 B , one embodiment of such a method involves isolating a substance  15  from a syringe plunger tip  130 . The methods may include applying a coating  140  to an external surface  134  of a syringe plunger tip  130 . The coating  140  may be applied via any of the deposition methods described herein. The methods may further include disposing the plunger tip  130  with its coating  140  within a reservoir  114  defined by an interior surface  112  of a syringe barrel  110 . The plunger tip  130  may be disposed by, for example, inserting it into the reservoir  114  through an opening  118  in syringe barrel  110 . The methods may further comprise loading the reservoir  114  with a substance  15 . The substance may be loaded in the reservoir  114 , e.g., through an opening  117  in a tip  116  of the syringe barrel  110  that is in communication with the reservoir  114 . 
     When plunger tip  130  is disposed in the reservoir  114 , and substance  15  is loaded in the reservoir  114 , coating  140  may provide a barrier between the plunger tip  130  and the substance  15 . In such a case, coating  140  isolates the substance  15  from plunger tip  130  by preventing direct contact between the material of the plunger tip  130  and the substance  15 . In addition, when the plunger is disposed in the reservoir  114  as described, coating  140  may isolate the substance from other syringe components as well (e.g., a plunger  120 ). In some embodiments, the substance may comprise PVA or gelatin foam, the plunger tip  130  may comprise silicone, and the coating  140  may comprise LLDPE, HDPE, ePTFE, PTFE, or a composite of any of these materials. 
     In some embodiments, a syringe system can comprise a barrel having a coating as described herein disposed on at least a portion of its interior surface.  FIG.  6    is a cross-sectional side view of an embodiment of a syringe system  600 . As depicted, the syringe system  600  can comprise a syringe body  605  comprising a barrel  610  and a plunger  620 . The syringe system  100  can also comprise an inlet/outlet port  128  disposed at a distal end of the syringe body  105 . As shown, the plunger  620  can comprise a plunger tip  630  coupled thereto. The barrel  610  may include an interior surface  612  and a coating  640  disposed on at least a portion of the interior surface  612 . In some embodiments, the coating may be cross-linked or otherwise bonded to the interior surface  612 . 
     The coating according to the present disclosure may comprise a material that is deposited onto the interior surface of the barrel by, for example, dip coating, sputtering, spray coating, or spin coating techniques. In some embodiments, electrospraying or electrospinning techniques may be used. In some embodiments, the coating may be cross-linked or otherwise bonded to the material of the interior surface. In some embodiments, the coating may have a thickness from about 0.1 μm to about 50 μm, or from about 0.5 μm to about 1.5 μm. 
     The coating according to the present disclosure may comprise a different material than that of the interior surface of the barrel. In some embodiments, the material properties of the materials used for the coating and the interior surface may differ in certain respects. Accordingly, the coating may comprise any suitable material including those that provide a reduced-friction interface, as compared to the interior surface material, between a plunger tip and the coated interior surface. Thus, the coating may comprise a material that provides a lower coefficient of friction between the plunger tip and the coating than the coefficient of friction between the plunger tip and the material of the interior surface without the coating. 
     The coatings of the present disclosure may also comprise a material that isolates the interior surface of the barrel from a substance loaded into the syringe barrel by preventing direct contact between the interior surface and the substance. Thus, the coating may comprise a material that is impermeable to the substance, and thereby reduce or eliminate the permeability of the interior surface for the substance. Coatings described herein may be used to reduce the permeability of syringe barrels or other components (e.g., stopcocks) comprising polycarbonates or other permeable materials. 
     The coating material may be formulated so as to be capable of adhering or bonding to the material of the interior surface. In some embodiments, the coating may comprise one or more polymeric materials. For example, the coating may comprise polyolefins, polyethylene, perfluoropolyether (PFPE), or perfluoropolyalkylether (PFAE). Polyethylene coatings may comprise LLDPE, HDPE, ePTFE, PTFE, or a composite of any of these materials. In some embodiments, the coating may comprise a thermoplastic elastomer. Thermoplastic elastomers for such use may comprise, without limitation, styrenic block copolymers, polyester-ester block copolymers, polyether-ester block copolymers, polyurethanes, polyamides or combinations thereof. 
     In some embodiments, the coating  640  may be configured to isolate the material of the syringe barrel  610  from materials within the reservoir of the syringe barrel  610 . The coating  640  may be less permeable than the material of the syringe barrel  610  and may prevent or reduce leaching of materials between the contents of the syringe barrel  610  and the material of the syringe barrel  610  and vice versa. 
     Further, in various embodiments the use of a coating as disclosed herein may reduce or eliminate the need to use a lubricant (e.g., a lubricant containing silicone) within the syringe assembly (e.g., within the syringe barrel), which, in turn, may prevent such a lubricant from contaminating or otherwise affecting a substance held within the syringe. For example, in some instances silicone lubricants may coat or otherwise interfere with the hydration of PVA or gelatin foams. Coatings used in place of silicone lubricant may therefore be configured for use with PVA or gelatin foams. Additionally or alternatively, in certain embodiments, a coating as disclosed herein may be used to achieve a specific breakaway force with respect to the movement of a plunger tip through a syringe barrel. This breakaway force may be between 0.5 lbf and 3 lbf, 1 lbf and 2 lbf, less than 3 lbf, less than 2 lbf, less than 1.5 lbf, or less than 1 lbf. In other embodiments, a coating as disclosed herein may configured such that coefficients of static and dynamic friction between the coating and a surface of the syringe assembly (e.g., the interior surface of the syringe barrel) are closely matched, for example within 5% of each other, which may facilitate smooth or even use of the syringe. 
     In any of the foregoing embodiments, the syringe assembly and components thereof may be sterilization compatible materials. “Sterilization compatible materials,” as used herein, refers to materials capable of being sterilized without rendering the materials unsuitable for their intended purposes. If a material is configured for sterilization by at least one method of sterilization without being rendered unsuitable for its intended purpose, then the material is a “sterilization compatible material.” For example, a polymeric barrel may deform when autoclaved at temperatures sufficient to sterilize the barrel, rendering the barrel unsuitable for its intended purpose of maintaining a seal with a cylindrical or circular plunger. However, if the same polymeric barrel may be sterilized by another sterilization technique, such as irradiation, and maintain suitability for its intended purpose, then the polymeric material is a “sterilization compatible material.” 
     In any of the foregoing embodiments, the syringe assembly and components thereof may be made from irradiation compatible materials. “Irradiation compatible materials,” as used herein, refers specifically to materials capable of being sterilized by irradiation without rendering the materials unsuitable for their intended purposes. For example, a plunger or interior surface of a barrel may comprise a material or lubricant that upon irradiation changes in physical properties such that the syringe is unsuitable for its intended purpose. For example, irradiation may alter certain materials or lubricants such that a syringe using those materials would have an unacceptably high initial peak force required to start movement of the plunger. Or, in another example, irradiation may alter certain materials or lubricants such that a syringe using those materials would have an unacceptably non-uniform force required for travel of the plunger over the length of the barrel or an unacceptably high force required for travel of the plunger over the length of the barrel. 
     The coating, syringe plunger tip, and other components disclosed herein may be used with a syringe loaded with any suitable substance for loading into a syringe. In certain embodiments, the syringe may be loaded with a substance comprising an embolic agent comprising a microparticle and/or microsphere. Examples of microparticles include polyvinyl alcohol (PVA) microparticles. Examples of microspheres include trisacryl cross-linked with gelatin microspheres, sodium acrylate vinyl alcohol copolymer microspheres, and polyvinyl alcohol based hydrogels. 
     While specific embodiments of coatings for syringes and methods related thereto have been described, it is to be understood that the disclosure provided is not limited to the precise configuration and components disclosed. Various modifications, changes, and variations apparent to those of skill in the art having the benefit of this disclosure may be made in the arrangement, operation, and details of the devices, methods, and systems disclosed, with the aid of the present disclosure. 
     Furthermore, any reference to “one embodiment,” “an embodiment,” or “the embodiment,” as used throughout this disclosure, means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment. 
     Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the present disclosure to its fullest extent. The examples and embodiments disclosed herein are to be construed as merely illustrative and exemplary and not as a limitation of the scope of the present disclosure in any way. It will be apparent to those having skill in the art, and having the benefit of this disclosure, that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the disclosure herein.