Biocompatible Layer Research Articles

Inert Coats of Magnetic Nanoparticles Prevent Formation of Occlusive Intravascular Co-aggregates With Neutrophil Extracellular Traps.

If foreign particles enter the human body, the immune system offers several mechanisms of response. Neutrophils forming the first line of the immune defense either remove pathogens by phagocytosis, inactivate them by degranulation or release of reactive oxygen species or immobilize them by the release of chromatin decorated with the granular proteins from cytoplasm as neutrophil extracellular traps (NETs). Besides viable microbes like fungi, bacteria or viruses, also several sterile inorganic particles including nanoparticles reportedly activate NET formation. The physicochemical nanoparticle characteristics fostering NET formation are still elusive. Here we show that agglomerations of non-stabilized superparamagnetic iron oxide nanoparticles (SPIONs) induce NET formation by isolated human neutrophils, in whole blood experiments under static and dynamic conditions as well as in vivo. Stabilization of nanoparticles with biocompatible layers of either human serum albumin or dextran reduced agglomeration and NET formation by neutrophils. Importantly, this passivation of the SPIONs prevented vascular occlusions in vivo even when magnetically accumulated. We conclude that higher order structures formed during nanoparticle agglomeration primarily trigger NET formation and the formation of SPION-aggregated NET-co-aggregates, whereas colloid-disperse nanoparticles behave inert and are alternatively cleared by phagocytosis.

Characterization and Modification of Adhesion in Dry and Wet Environments in Thin-Film Parylene Systems

Parylene C is a thin-film polymer used as a biocompatible barrier layer in biomedical implants and implantable MEMS; free-film Parylene C may serve as both the substrate and insulation in polymer-based microdevices, a growing branch of biomedical technology. The adhesion of vapor deposited Parylene C, particularly when exposed to wet, in vivo environments, is a critical determinant of device lifetime for such polymer-based implants. This paper explores several novel strategies for improving the adhesion of multi-layer Parylene structures, including thermal annealing and the use of several chemical interposer layers. Interfacial adhesion of Parylene-Parylene and Parylene-platinum-Parylene films was examined using a standard T-peel test to quantify adhesion and measure film integrity under chronic exposure to saline up to two years. Improved adhesion and barrier properties in Parylene-Parylene films resulted from the inclusion of diamond-like carbon and ethylene glycol diacrylate layers. Thermal annealing improved Parylene film integrity in wet environments but was insufficient for improving the integrity of Parylene-platinum interfaces. A 100-fold increase in adhesive strength at such interfaces was achieved using a commercially available adhesion promoter, and the corresponding improvements in resistance to moisture driven delamination were observed. X-ray diffraction and X-ray photoelectron spectroscopy results are provided to highlight the role of film morphology and surface composition in adhesion integrity. [2018-0076]

Detection of bacterial metabolism in lag-phase using impedance spectroscopy of agar-integrated 3D microelectrodes

Traditional methods for detection of metabolically-active bacterial cells, while effective, require several days to complete. Development of sensitive electrical biosensors is highly desirable for rapid detection and counting of pathogens in food, water, or clinical samples. Herein, we develop a highly-sensitive non-Faradaic impedance sensor which detects metabolic activity of E. coli cells in a mere 1 μl of sample volume and without any sample filtration/purification. The three dimensional (3D) interdigitated electrodes (IDEs) along with self-assembled gold-nickel (Au-Ni) nanostructures significantly amplify the sensitivity by increasing the sensing area almost three-fold. The developed microsystem is integrated with an agar-based growth medium and monitors the metabolism of bacterial cells, enabling bacterial detection in approximately one hour after inoculation, i.e. in the lag-phase. Incorporation of a secondary agar layer as a biocompatible passivation layer protects the IDEs from potential Faradaic reactions and enhances sensitivity to modulation of the non-Faradaic impedance due to cellular metabolism. The resultant label-free sensor is capable of selective identification of metabolizing cells (vs. dead cells) across a wide linear range (10–1000 cells/μl). These results help pave the way for rapid antibacterial susceptibility testing at the point-of-need, which is currently a major challenge in healthcare.

Microencapsulated adult porcine islets transplanted intraperitoneally in streptozotocin‐diabetic non‐human primates

Xenogeneic donors would provide an unlimited source of islets for the treatment of type 1 diabetes (T1D). The goal of this study was to assess the function of microencapsulated adult porcine islets (APIs) transplanted ip in streptozotocin (STZ)-diabetic non-human primates (NHPs) given targeted immunosuppression. APIs were encapsulated in: (a) single barium-gelled alginate capsules or (b) double alginate capsules with an inner, islet-containing compartment and a durable, biocompatible outer alginate layer. Immunosuppressed, streptozotocin-diabetic NHPs were transplanted ip with encapsulated APIs, and graft function was monitored by measuring blood glucose, %HbA1c, and porcine C-peptide. At graft failure, explanted capsules were assessed for biocompatibility and durability plus islet viability and functionality. Host immune responses were evaluated by phenotyping peritoneal cell populations, quantitation of peritoneal cytokines and chemokines, and measurement of anti-porcine IgG and IgM plus anti-Gal IgG. NHP recipients had reduced hyperglycemia, decreased exogenous insulin requirements, and lower percent hemoglobin A1c (%HbA1c) levels. Porcine C-peptide was detected in plasma of all recipients, but these levels diminished with time. However, relatively high levels of porcine C-peptide were detected locally in the peritoneal graft site of some recipients at sacrifice. IV glucose tolerance tests demonstrated metabolic function, but the grafts eventually failed in all diabetic NHPs regardless of the type of encapsulation or the host immunosuppression regimen. Explanted microcapsules were intact, "clean," and free-floating without evidence of fibrosis at graft failure, and some reversed diabetes when re-implanted ip in diabetic immunoincompetent mice. Histology of explanted capsules showed scant evidence of a host cellular response, and viable islets could be found. Flow cytometric analyses of peritoneal cells and peripheral blood showed similarly minimal evidence of a host immune response. Preformed anti-porcine IgG and IgM antibodies were present in recipient plasma, but these levels did not rise post-transplant. Peritoneal graft site cytokine or chemokine levels were equivalent to normal controls, with the exception of minimal elevation observed for IL-6 or IL-1β, GRO-α, I-309, IP-10, and MCP-1. However, we found central necrosis in many of the encapsulated islets after graft failure, and explanted islets expressed endogenous markers of hypoxia (HIF-1α, osteopontin, and GLUT-1), suggesting a role for non-immunologic factors, likely hypoxia, in graft failure. With donor xenoislet microencapsulation and host immunosuppression, APIs corrected hyperglycemia after ip transplantation in STZ-diabetic NHPs in the short term. The islet xenografts lost efficacy gradually, but at graft failure, some viable islets remained, substantial porcine C-peptide was detected in the peritoneal graft site, and there was very little evidence of a host immune response. We postulate that chronic effects of non-immunologic factors, such as in vivo hypoxic and hyperglycemic conditions, damaged the encapsulated islet xenografts. To achieve long-term function, new approaches must be developed to prevent this damage, for example, by increasing the oxygen supply to microencapsulated islets in the ip space.

The correlation between substrate and deposited biocompatible layer microstructures on different substrates

The biocompatibility is essential for the so called biomaterials used for medical devices (e.g. artificial implants, implants). It is determined mainly by the surface chemical composition and the environment in which the implant is used. The implant materials used till the date have limited biocompatibility. On the other hand newly developed biocompatible materials are usually more expensive. The biocompatibility of currently used materials can be improved via deposition of thin biocompatible layer on the substrate. This layer may be further improved (or used as interlayer) introducing hydroxyapatite, BaTiO3 or other surface treatments. The microstructure of deposited layers has to be known in such cases as it can influence properties of the surface. Various substrates (pure titanium, Ti6Al4V alloy and Ti-39Nb alloy) were used for biocompatible Ti-39Nb layer sputtering deposition in current paper. The microstructure of substrates has been characterized using electron microscopy techniques. The correlation between substrate and layer microstructures could have been revealed, because both microstructures were studied at the same area of the substrate. Significant differences in grain size have been observed on various substrates. Also the microstructure of deposited layer can be distinguished into two types. These are pure β-Ti phase probably on the grains where the surface diffusivity is high enough (locally observed on Ti-39Nb and pure Ti substrates) and mixture of α″ martensitic and β-Ti phase columns.

Directly repurposing waste optical discs with prefabricated nanogrooves as a platform for investigation of cell-substrate interactions and guiding neuronal growth

Due to rapid change in information technology, many consumer electronics become electronic waste which is the fastest-growing pollution problems worldwide. In fact, many discarded electronics with prefabricated micro/nanostructures may provide a good basis to fulfill special needs of other fields, such as tissue engineering, biosensors, and energy. Herein, to take waste optical discs as an example, we demonstrate that discarded electronics can be directly repurposed as highly anisotropic platforms for in vitro investigation of cell behaviors, such as cell adhesion, cell alignment, and cell-cell interactions. The PC12 cells cultured on biocompatible DVD polycarbonate layers with flat and grooved morphology show a distinct cell morphology, indicating the topographical cue of nanogrooves plays a key role in guidance of neurites growth. By further monitoring cell morphology and alignment of PC12 cells cultured on the DVD nanogrooves at different differentiation times, we find that cell contact interaction with nanotopographies is dynamically adjustable with differentiation time from initial disorder to final order. This study adds a new dimension to not only solving the problems of supply of materials and fabrication of nanopatterns in neural tissue engineering, but may also offering a new promising way of waste minimization or reuse for environmental protection.

Tensile strain-controlled drug delivery system based on a cracked metal structure

Recently, mechanical stimuli-responsive drug delivery systems have received much attention as they have the advantages of being easily accessible for self-administered therapeutics and requiring no additional equipment. In this study, we report a tensile strain-controlled drug delivery system based on a micro-cracked membrane. The membrane consists of a drug-loaded polyurethane polymer layer coated with a biocompatible titanium metal layer. On application of external tensile strain to the membrane, micro-sized cracks are generated and propagate in the metallic layer. The exposed crack region acts as a channel for the drug molecules to diffuse into the surrounding buffer solution. We utilized the membrane as a drug delivery system by controlling the exposed crack region, which is dependent on the applied strain. Our results indicated that the amount of released drug increased with the applied strain, and the drug release profile had a highly linear correlation with the ‘ratio of exposed region’ in both experimental and numerical results (greater than 0.9). Although the developed crack-based drug release system has limitations such as drug leakage under the 0% strain condition, we believe that this drug release system can be a useful tool as an on-demand mechanically stimulated controlled drug delivery system, especially for applications requiring continued and long-term drug delivery.

Use of SU8 as a stable and biocompatible adhesion layer for gold bioelectrodes

Gold is the most widely used electrode material for bioelectronic applications due to its high electrical conductivity, good chemical stability and proven biocompatibility. However, it adheres only weakly to widely used substrate materials such as glass and silicon oxide, typically requiring the use of a thin layer of chromium between the substrate and the metal to achieve adequate adhesion. Unfortunately, this approach can reduce biocompatibility relative to pure gold films due to the risk of the underlying layer of chromium becoming exposed. Here we report on an alternative adhesion layer for gold and other metals formed from a thin layer of the negative-tone photoresist SU-8, which we find to be significantly less cytotoxic than chromium, being broadly comparable to bare glass in terms of its biocompatibility. Various treatment protocols for SU-8 were investigated, with a view to attaining high transparency and good mechanical and biochemical stability. Thermal annealing to induce partial cross-linking of the SU-8 film prior to gold deposition, with further annealing after deposition to complete cross-linking, was found to yield the best electrode properties. The optimized glass/SU8-Au electrodes were highly transparent, resilient to delamination, stable in biological culture medium, and exhibited similar biocompatibility to glass.

A Biocompatible Slippery Surface Based on a Boehmite Nanostructure with Omniphobicity for Hot Liquids and Boiling Stability

Omniphobic surfaces have attracted much attention and have a lot of applications in various fields. In particular, the application of omniphobicity to containers of prepackaged foods such as curry is extremely important for reducing food waste because they are especially liable to remain in the container owing to their high viscosity. To realize such application, the surface must be biocompatible to prevent health damage to the human body. However, few omniphobic surfaces with biocompatibility have been developed. Here, we present a silicone oil-immobilized biocompatible slippery surface with omniphobicity. A biocompatible base layer to immobilize the silicone oil as a lubricant was fabricated by combining a boehmite nanostructure and silicone oil grafting through thermal treatment. The slippery surface demonstrated omniphobicity not only for room-temperature liquids but also for high-temperature liquids including hot liquid foods. In addition, the surface exhibited long-term stability against boiling in ...

Wearable strain sensing textile based on one-dimensional stretchable and weavable yarn sensors

Flexible, wearable, and even stretchable sensors are the key components of smart electronic textiles. However, most reported flexible and wearable sensors for wearable electronics are usually fabricated in two-dimensional (2D) planar strip configurations, which cannot be properly integrated into textile structures and thus greatly degrade intrinsic properties such as the softness, flexibility, and air permeability of textiles and the aesthetic feeling of clothing. In this work, a new one-dimensional weavable strain sensing yarn consisting of an elastic polyurethane (PU) core, a conductive Ag-nanoparticles/graphene-microsheets composite sheath, and a silicone encapsulation layer was designed and fabricated through an easily manipulated protocol. Arising from the reasonable structural design and appropriate material selection, the as-fabricated strain sensor not only exhibited excellent flexibility, stretchability, and highly repeatable electromechanical stability (a repeatability error of 1.56%) but also possessed both high sensitivity (a gauge factor of nearly 500) and a relatively wide working range (0–50% applied strain) with good linearity (a correlation coefficient of 0.98). In addition, the facile, nearly all-solution-based fabrication protocol enabled the scalable production of long conductive yarns. Thus, the proper yarn length and superb mechanical properties endowed the stretchable conductive yarn with good weavability. The excellent wearability of the stretchable conductive yarn was derived from the outermost isolating, hydrophobic, and biocompatible silicone encapsulation layer. A wearable high-sensitivity strain sensing textile, fabricated by directly weaving the as-prepared yarn-based sensor, showed great potential for application to wearable textile sensors for real-time monitoring of human motions from vigorous walking to subtle and complex pronunciations.

Thermally Crosslinked Biocompatible Hydrophilic Polyvinylpyrrolidone Coatings on Polypropylene with Enhanced Mechanical and Adhesion Properties

We developed a stable hydrophilic biocompatible hydrogel-forming coating for polypropylene (PP)-based disposal medical applications. Although PP has a variety of advantages, including good stability and inertness in medical applications, tissue damage and insertion resistance are observed upon insertion of PP-based devices into the human body due to the high hydrophobicity of the PP surface. These issues limit the utility of PP in medical applications. To address these problems, we sought to develop a stable hydrophilic and biocompatible hydrogel-forming layer using polyvinyl pyrrolidone (PVP) combined with a crosslinked polyethyleneglycolacrylate (PEGDA) matrix. Systematic studies of the blended hydrogel-forming PVP:PEGDA were conducted using a variety of blending ratios between the two polymers. The hydrophilicity and water-affinity of the hydrogel-forming layer improved significantly as the PEGDA-to-PVP blending ratio increased. Importantly, the tensile strain at the break point increased by a factor of more than 7, and the strength of adhesion to the PP surface for the 1:1 PVP:PEGDA (PVP(1):PEGDA(1)) blend ratio was 54 times that of the PVP film, determined using tensile strain–stress and peel tests. The water stability of the PVP(1):PEGDA(1) improved significantly. This approach is potentially useful as a biocompatible hydrophilic polymer coating in a variety of low-priced consumable PP commercial medical applications.

A Fluorine-free Slippery Surface with Hot Water Repellency and Improved Stability against Boiling.

Inspired by natural living things such as lotus leaves and pitcher plants, researchers have developed many excellent antifouling coatings. In particular, hot-water-repellent surfaces have received much attention in recent years because of their wide range of applications. However, coatings with stability against boiling in hot water have not been achieved yet. Long-chain perfluorinated materials, which are often used for liquid-repellent coatings owing to their low surface energy, hinder the potential application of antifouling coatings in food containers. Herein, we design a fluorine-free slippery surface that immobilizes a biocompatible lubricant layer on a phenyl-group-modified smooth solid surface through OH-π interactions. The smooth base layer was fabricated by modification of phenyltriethoxysilane through a sol-gel method. The π-electrons of the phenyl groups interact with the carboxyl group of the oleic acid used as a lubricant, which facilitates immobilization on the base layer. Water droplets slid off the surface in the temperature range from 20 to 80 °C at very low sliding angles (<2°). Furthermore, we increased the π-electron density in the base layer to strengthen the OH-π interactions, which improved long-term boiling stability under hot water. We believe that this surface will be applied in fields in which the practical use of antifouling coatings is desirable, such as food containers, drink cans, and glassware.

Investigation of nanoporosities fabricated on metallic glass surface by hydroxyapatite mixed EDM for orthopedic application

Bulk metallic glasses (BMGs) have exceptional biomechanical characteristics like low elastic modulus, outstanding fracture strength, superior wear and corrosion resistance compared to routinely used biomaterials. The major downside of BMG is its inability to osteointegrate to the surrounding living tissues. To solve this problem, a biocompatible and bone-like nanoporous layer are normally imparted on the implant surface. In this study, a very hard, biocompatible and nano-porous layer was deposited on the Zr-based metallic glass surface, by hydroxyapatite mixed electrical discharge machining (HA-EDM). FESEM was employed to observe the pore distribution, geometry, and sizes. The result reveals the formation of rough, narrow craters and interconnected nanoporosities in the range of 558.2 nm to 893 nm in diameter and surface area of 244764 nm2 to 626596 nm2. However, the XRD and EDX characterization revealed the deposition of ZrC, TiC and CaTiO3 on the HA-EDMed surface. The surface produced by HA-EDM is expected to facilitate higher tissue in-growth and bone-implant adhesion.

Kinetics and Chemistry of Hydrolysis of Ultrathin, Thermally Grown Layers of Silicon Oxide as Biofluid Barriers in Flexible Electronic Systems.

Flexible electronic systems for bioimplants that offer long-term (multidecade) stability and safety in operation require thin, biocompatible layers that can prevent biofluid penetration. Recent work shows that ultrathin films of silicon dioxide thermally grown (TG-SiO2) on device-grade silicon wafers and then released as transferrable barriers offer a remarkable set of attributes in this context. This paper examines the chemical stability of these materials in aqueous solutions with different combinations of chemistries that are present in biofluids. Systematic measurements reveal the dependence of the dissolution rate of TG-SiO2 on concentrations of cations (Na+, K+, Mg2+, Ca2+) and anions (Cl-, HPO42-) at near-neutral pH. Certain results are consistent with previous studies on bulk samples of quartz and nanoparticles of amorphous silica; others reveal significant catalyzing effects associated with divalent cations at high pH and with specific anions at high ionic strength. In particular, Ca2+ and HPO42- greatly enhance and silicic acid greatly reduces the rates. These findings establish foundational data of relevance to predicting lifetimes of implantable devices that use TG-SiO2 as biofluid barriers, and of other classes of systems, such as environmental monitors, where encapsulation against water penetration is important.

Synthesis, characterisation, cellular uptake and cytotoxicity of functionalised magnetic ruthenium (II) polypyridine complex core-shell nanocomposite

The development of multifunctional nanoparticles comprising of a magnetic core in conjunction with appropriate molecules with capabilities to impart functionalities like luminescent, specific binding sites to facilitate attachment of moieties. This has attracted increasing attention and enables identification of promising candidates using for applications such as diagnostics and cure through early detection and localized delivery. Many studies have been performed on the synthesis and cellular interactions of core–shell nanoparticles, in which a functional inorganic core is coated with a biocompatible polymer layer that should reduce nonspecific uptake and cytotoxicity Here we report the synthesis and characterisation of multifunctional core-shell magnetic, luminescent nanocomposite (Fe3O4@SiO2@[Ru(Phen)3]2+@SiO2@NH2). Fe3O4 as core and a luminescent ruthenium (II) complex encapsulated with silica shell, and then it is functionalized by an amine group by APTMS. The magnetic, luminescent, and biological activity of this multifunctional nanocomposite have also been studied to prove the nanocomposite is biocompatible, cellular uptake. The synthesized nanocomposite was completely characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and emission spectroscopy. MTT assay and cellular uptake by flow cytometry results proved that magnetic ruthenium (II) polypyridine complex – core shell nanocomposite has biocompatibility, minimum cytotoxicity and internalized inside B16F10 cells and confirms the potential biomedical applications.

Organic memristive devices based on pectin as a solid polyelectrolyte

Novel architectures of organic memristive device with pectin as a solid polyelectrolyte have been developed and studied. The assembled devices exhibit memristive properties (hysteresis and rectification) emulating the signal process and memory functions of biological synapses. This work reveals for the first time that pectin from fruit peel is a promising material for nonvolatile memory applications based on polyaniline electrochemistry. In addition, we have demonstrated that under well-defined conditions, pectin can play the role of an intermediate biocompatible layer interfacing the electronic device with the living organism preserving functions of both. In particular, the pectin interfacing layer in this case maintains polyaniline conductivity without the presence of strong inorganic acids. The method was successfully validated by developing a hybrid bio-memristive electrochemical device with living organism Physarum polycephalum.

Coaxial‐Structured Weavable and Wearable Electroluminescent Fibers

AbstractFlexible, lightweight, and wearable devices are currently attracting tremendous interest in the field of advanced electronics. In this work, novel 1D, flexible, coaxial‐structured, bright and colorful alternating current electroluminescent (ACEL) fibers consisting of AgNW‐based electrodes, a ZnS phosphor layer, and silicone dielectric and encapsulation layers are designed and fabricated through a simple protocol. This facile all‐solution‐based fabrication protocol enables scalable production of long ACEL fibers (&gt;12 cm). Stemming from the rational design and facile fabrication process, the as‐prepared ACEL fibers exhibit uniform, bright, and angularly independent luminance (up to 202 cd m−2 @ 195 V and 2 kHz). Benefiting mainly from the robust AgNW‐based electrodes and versatile silicone, the ACEL fibers exhibit additionally excellent flexibility and mechanical stability, being capable to maintain ≈91% of luminance after 500 bending‐recovery cycles, as well as mitigated luminance degradation after continuous work in ambient. The proper length combined with superb mechanical properties makes the ACEL fibers readily weavable. Most notably, the isolating, hydrophobic, and biocompatible silicone encapsulation layer endows the ACEL fibers unprecedented wearability. Eventually, a proof‐of‐concept ACEL fabric is demonstrated by weaving the as‐prepared long ACEL fibers, to show the future perspective of directly weaving ACEL fibers into densely arrayed wearable functional cloths.

The influence of periodical, interference laser micromachining on nano-crystallization of amorphous magnetic ribbons

The main problem connected with crystallization of amorphous magnetic materials from the FeSiB(X) group is the increase of their fragility with the increasing content of crystalline phase. To overcome this defect the possibilities offered by the interference, pulse laser heating of FeSiB ribbons were utilized. A simple, interference prismatic system at the output of Nd:YAG laser (8-10 ns, 2 J, 1064 nm) was used. The investigations included the influence of laser radiation energy density, number of laser pulses and their periodical, spatial surface arrangement on the crystallization process. Full Text: PDF ReferencesY.R. Zhang and R.V. Ramanujan, "A study of the crystallization behavior of an amorphous Fe77.5Si13.5B9 alloy", Mater. Sci. Eng. A 416, 161 (2006). CrossRef T. Alam, T. Borkar, S. Joshi, S. Katakamb, X. Chenc and N.B. Dahotre, "Influence of niobium on laser de-vitrification of Fe-Si-B based amorphous magnetic alloys", J. Non-Cryst. Solids 428, 75 (2015). CrossRef K.G. Pradeep, G. Herzer, P. Choi and D. Raabe, "Atom probe tomography study of ultrahigh nanocrystallization rates in FeSiNbBCu soft magnetic amorphous alloys on rapid annealing", Acta Mater. 68, 295 (2014). CrossRef S. Katakam, J.Y. Hwang, H. Vora, S.P. Harimkar, R. Banerjee and N.B. Dahotre, "Laser-induced thermal and spatial nanocrystallization of amorphous Fe-Si-B alloy", Scr. Mater. 66, 538 (2012). CrossRef J. Kusiński, A. Sypień, G. Kusiński and C. Nilson, "Microstructure and nanochemistry of Ca-doped cobalt oxide single crystals", Mat. Chem. Phys. 81, 390 (2003). CrossRef C. Smith, S. Katakam, S. Nag, X. Chen, R.V. Ramanujan, N.B. Dahotre and R. Banerjee, "Improved soft magnetic properties by laser de-vitrification of Fe-Si-B amorphous magnetic alloys", Mater. Lett. 122, 155 (2014). CrossRef Ch. Lu and R. H. Lipson, "Interference lithography: a powerful tool for fabricating periodic structures", Laser Photonics Rev. 4, 568 (2010). CrossRef K. Czyż, J. Marczak, R. Major, A. Mzyk, A. Rycyk, A. Sarzyński and M. Strzelec, "Selected laser methods for surface structuring of biocompatible diamond-like carbon layers", Diam. Relat. Mater. 67, 26 (2016). CrossRef A. Sarzyński, J. Marczak, M. Strzelec, A. Rycyk, K. Czyż and D. Chmielewska, "Laser micro-structuring of surfaces for applications in materials and biomedical science", Proc. SPIE, 10159, 101590A (2016). CrossRef

Nanofilm of ZnO nanocrystals/carbon nanotubes as biocompatible layer for enzymatic biosensors in capacitive field-effect devices

The incorporation of nanomaterials that are biocompatible with different types of biological compounds has allowed the development of a new generation of biosensors applied especially in the biomedical field. In particular, the integration of film-based nanomaterials employed in field-effect devices can be interesting to develop biosensors with enhanced properties. In this paper, we studied the fabrication of sensitive nanofilms combining ZnO nanocrystals and carbon nanotubes (CNTs), prepared by means of the layer-by-layer (LbL) technique, in a capacitive electrolyte-insulator-semiconductor (EIS) structure for detecting glucose and urea. The ZnO nanocrystals were incorporated in a polymeric matrix of poly(allylamine) hydrochloride (PAH), and arranged with multi-walled CNTs in a LbL PAH-ZnO/CNTs film architecture onto EIS chips. The electrochemical characterizations were performed by capacitance–voltage and constant capacitance measurements, while the morphology of the films was characterized by atomic force microscopy. The enzymes glucose oxidase and urease were immobilized on film’s surface for detection of glucose and urea, respectively. In order to obtain glucose and urea biosensors with optimized amount of sensitive films, we investigated the ideal number of bilayers for each detection system. The glucose biosensor showed better sensitivity and output signal for an LbL PAH-ZnO/CNTs nanofilm with 10 bilayers. On the other hand, the urea biosensor presented enhanced properties even for the first bilayer, exhibiting high sensitivity and output signal. The presence of the LbL PAH-ZnO/CNTs films led to biosensors with better sensitivity and enhanced response signal, demonstrating that the adequate use of nanostructured films is feasible for proof-of-concept biosensors with improved properties that may be employed for biomedical applications.

Formation of biocompatible surface layers depending on the sputtering distance

Nano- and micro-dimensional surface layers of silver and tantalum on flat and wire NiTi substrates by the method of magnetron sputtering in vacuum were produced. The structure and composition of the samples were determined using SEM and Auger spectroscopy. With an increase in the sputtering distance, the thickness of the surface layers decreases, and the thickness of the transition layer and the dependence of the thickness change as a whole depend on the nature of the sputtered substance.