Polyvinylpyrrolidone Coatings Research Articles

Electrophoretic Deposition of 58S Bioactive Glass- Polymer Composite Coatings on 316L Stainless Steel: An Optimization for Corrosion, Bioactivity, and Cytocompatibility.

This study presents a facile fabrication of 58S bioactive glass (BG)-polymer composite coatings on a 316L stainless steel (SS) substrate using the electrophoretic deposition technique. The suspension characteristics and deposition kinetics of BG, along with three different polymers, namely ethylcellulose (EC), poly(acrylic acid) (PAA), and polyvinylpyrrolidone (PVP), have been utilized to fabricate the coatings. Among all coatings, 58S BG and EC polymers are selected as the final composite coating (EC6) owing to their homogeneity and good adhesion. EC6 coating exhibits a thickness of ∼18 μm and an average roughness of ∼2.5 μm. Herein, EC6 demonstrates better hydroxyapatite formation compared to PAA and PVP coatings in simulated body fluid-based mineralization studies for a period of 28 days. Corrosion studies of EC6 in phosphate-buffered saline further confirm the higher corrosion resistance properties after 14 days. In vitro cytocompatibility studies using human placental mesenchymal stem cells demonstrate an increase in cellular viability, attachment, and higher proliferation compared to the bare SS substrate. EC6 coatings promote osteogenic differentiation, which is confirmed via the upregulation of the OPN and OCN genes. Moreover, the EC6 sample exhibits improved antibacterial properties against Escherichia coli and Staphylococcus aureus compared to the uncoated ones. The findings of this work emphasize the potential of electrophoretically fabricated BG-EC composite coatings on SS substrates for orthopedic applications.

Radiation Modified CS/PVA Film with PVP Coating as Cu Adsorbent Material

Chitosan/Polyvinyl alcohol (CS/PVA) films were coated with layer of polyvinyl pyrrolidone (PVP) to improve its mechanical strength. In this study, chitosan/PVA mixture was first cast into film. The films were later dipped into different concentrations of PVP solutions at 1%, 3%, and 5%. They were then exposed to gamma (γ) radiation at 5,10,20 and 30 kGy. The tensile strength of chitosan/PVA films coated with 1% PVP was found to increase up to 31%. Elongation at break was improved by 1% PVP coating. The CS/PVA Removal Efficiency (RE) with or without PVP coatings were not affected by γ irradiation. Result shows that the best settings to enhance the tensile strength of CS/PVA films for Cu adsorption application was 1% PVP coating at 5 kGy γ radiation.

Mobility-Enhancing Coatings for Vitreoretinal Surgical Devices: Hydrophilic and Enzymatic Coatings Investigated by Microrheology.

Ophthalmic wireless microrobots are proposed for minimally invasive vitreoretinal surgery. Devices in the vitreous experience nonlinear mobility as a result of the complex mechanical properties of the vitreous and its interaction with the devices. A microdevice that will minimize its interaction with the macromolecules of the vitreous (i.e., mainly hyaluronan (HA) and collagen) can be utilized for ophthalmic surgeries. Although a few studies on the interactions between the vitreous and microdevices exist, there is no literature on the influence of coatings on these interactions. This paper presents how coatings on devices affect mobility in the vitreous. Surgical catheters in the vasculature use hydrophilic polymer coatings that reduce biomolecular absorption and enhance mobility. In this work such polymers, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and HA coatings were utilized, and their effects on mobility in the vitreous were characterized. Hydrophilic titanium dioxide (TiO2) coating was also developed and characterized. Collagenase and hyaluronidase enzymes were coated on probes' surfaces with a view to enhancing their mobility by enzymatic digestion of the collagen and HA of the vitreous, respectively. To model the human vitreous, ex vivo porcine vitreous and collagen were used. For studying the effects of hyaluronidase, the vitreous and HA were used. The hydrophilic and enzymatic coatings were characterized by oscillatory magnetic microrheology. The statistical significance of the mean relative displacements (i.e., mobility) of the coated probes with respect to control probes was assessed. All studied hydrophilic coatings improve mobility, except for HA which decreases mobility potentially due to bonding with vitreal macromolecules. TiO2 coating improves mobility in collagen by 28.3% and in the vitreous by 15.4%. PEG and PVP coatings improve mobility in collagen by 19.4 and by 39.6%, respectively, but their improvement in the vitreous is insignificant at a 95% confidence level (CL). HA coating affects mobility by reducing it in collagen by 35.6% (statistically significant) and in the vitreous by 16.8% (insignificant change at 95% CL). The coatings cause similar effects in collagen and in the vitreous. However, the effects are lower in the vitreous, which can be due to a lower concentration of collagen in the vitreous than in the prepared collagen samples. The coatings based on enzymatic activity increase mobility (i.e., >40% after 15 min experiments in the vitreous models) more than the hydrophilic coatings based on physicochemical interactions. However, the enzymes have time-dependent effects, and they dissolve from the probe surface with time. The presented results are useful for researchers and companies developing ophthalmic devices. They also pave the way to understanding how to adjust mobility of a microdevice in a complex fluid by choice of an appropriate coating.

Sulfonated nanocellulose for the efficient dispersive micro solid-phase extraction and determination of silver nanoparticles in food products

This paper reports a simple approach to Analytical Nanoscience and Nanotechnology (AN&N) that integrates the nanotool, sulfonated nanocellulose (s-NC), and nanoanalyte, silver nanoparticles (AgNPs), in the same analytical process by using an efficient, environmentally friendly dispersive micro solid-phase extraction (D-μSPE) capillary electrophoresis (CE) method with s-NC as sorbent material. Introducing negatively charged sulfate groups onto the surface of cellulose enhances its surface chemistry and enables the extraction and preconcentration of AgNPs of variable diameter (10, 20 and 60nm) and shell composition (citrate and polyvinylpyrrolidone coatings) from complex matrices into a cationic surfactant. In this way, AgNPs of diverse nature were successfully extracted onto the s-NC sorbent and then desorbed into an aqueous solution containing thiotic acid (TA) prior to CE without the need for any labor-intensive cleanup. The ensuing eco-friendly D-μSPE method exhibited a linear response to AgNPs with a limit of detection (LOD) of 20μg/L. Its ability to specifically recognize AgNPs of different sizes was checked in orange juice and mussels, which afforded recoveries of 70.9–108.4%. The repeatability of the method at the limit of quantitation (LOQ) level was 5.6%. Based on the results, sulfonated nanocellulose provides an efficient, cost-effective analytical nanotool for the extraction of AgNPs from food products.

Efficiency Enhancement of Cu(In,Ga)Se2 Solar Cells by Applying SiO2–PEG/PVP Antireflection Coatings

An effective approach was presented to enhance photoelectric conversion efficiency of Cu(In,Ga)Se2 (CIGS) solar cells by using modified SiO2 antireflection coatings (ARCs) to harvest more incident sunlight. Polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) used as additives were introduced into silica sols to prepare SiO2–PEG and SiO2–PVP coatings in the sol–gel dip-coating process, respectively. The different effects of PEG and PVP additives on SiO2 coatings were analyzed and the antireflection performance of SiO2–PEG and SiO2–PVP coatings was investigated. The transmittance over 97% ranging from 450 nm to 700 nm with a maximum transmittance over 99.40% at about 550 nm was achieved for both SiO2–PEG2000A and SiO2–PVP0.5 coatings. The relative efficiencies of CIGS solar cells coated with SiO2–PEG2000A and SiO2–PVP0.5 ARCs were increased by 7.27% and 8.33%, respectively. The modified SiO2 ARCs possessed the advantages of the low manufacturing cost, good adhesion, superior antireflective performance and the feasible method for large area fabrication.

Bi‐channel Surface Acoustic Wave Gas Sensor for Carbon Disulfide and Methanol Vapors in Polymer Plants

AbstractA C60‐polyphenylacetylene (C60‐PPA) and polyvinylpyrrolidone (PVP) coated two‐channel surface acoustic wave (SAW) crystal gas sensor with a homemade computer interface for data acquisition and data processing was developed and employed to detect carbon disulfide (CS2) and methanol (CH3OH) vapors in polymer plants. The frequency of surface acoustic wave oscillator decreases due to the adsorption of gas molecules on the coated materials of the SAW sensor. Six coating materials (C60‐PPA, nafion, PPA, crytand [2,2], polyethene glycol and PVP) were used to adsorb and detect carbon disulfide and methanol gases. Adsorption of all the six coating materials to CS2 and CH3OH was found to be physical adsorption. The C60‐PPA coated SAW detector exhibited more sensitive to CS2 than the other coating materials. In contrast, the PVP coated SAW detector was more sensitive to CH3OH than the other coating materials. With the two‐channel SAW sensor, the C60‐PPA coated SAW showed a good detection limit of 0.4 ppm and good reproducibility with RSD of 3.37 % (n=10) for CS2. Similarly, the PVP coated SAW also showed a good detection limit of 0.05 ppm and good reproducibility, with RSD of 0.86 % (n=10) for CH3OH. The interference effect of other organic molecules on the SAW detection system was negligible, except for the irreversible adsorption of C60‐PPA to propylamine. The frequency signals from the two‐channel SAW sensor array C60‐PPA and PVP coatings were processed by a back‐propagation artificial neural network (BPN) and multiple regression analysis (MRA). Thus a two‐channel SAW sensor array with BPN and MRA has been successfully applied for the qualitative and quantitative analyses of CS2 and CH3OH in mixtures.

Biofilm formation on coated silicone tympanostomy tubes

ObjectivesTympanostomy tube (TT) surface modifications have been promoted as a means of reducing biofilm formation, otorrhea, and occlusion. The goal of this study was to determine if biofilm formation on silicone TTs could be prevented by commercially available surface coatings. MethodsSilicone TTs with and without polyvinylpyrrolidone (PVP) or/and silver oxide were exposed to human plasma and cultured with Pseudomonas aeruginosa or Staphylococcus aureus (22 TTs per group). After 4 days, antibiotics were added to kill planktonic bacteria. Biofilm formation was assessed by quantitative bacterial counts and scanning electron microscopy. ResultsPVP, silver, and PVP–silver coatings reduced P. aeruginosa biofilm formation relative to silicone by over 1 log (p<0.0001). PVP was superior to silver (p=0.04) and PVP–silver (p<0.0001). PVP and PVP–silver coatings increased S. aureus biofilm formation nominally (p=0.01 & 0.003). ConclusionPVP and silver coatings reduce P. aeruginosa biofilm formation on silicone TTs. Combining PVP and silver coatings does not further improve biofilm resistance. TT surface coatings warrant further study through clinical trials.

Two solutions of the three-dimensional problem of limit waves on the surface of a ponderable fluid

An effective approach was presented to enhance photoelectric conversion efficiency of Cu(In,Ga)Se2 (CIGS) solar cells by using modified SiO2 antireflection coatings (ARCs) to harvest more incident sunlight. Polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) used as additives were introduced into silica sols to prepare SiO2–PEG and SiO2–PVP coatings in the sol–gel dip-coating process, respectively. The different effects of PEG and PVP additives on SiO2 coatings were analyzed and the antireflection performance of SiO2–PEG and SiO2–PVP coatings was investigated. The transmittance over 97% ranging from 450 nm to 700 nm with a maximum transmittance over 99.40% at about 550 nm was achieved for both SiO2–PEG2000A and SiO2–PVP0.5 coatings. The relative efficiencies of CIGS solar cells coated with SiO2–PEG2000A and SiO2–PVP0.5 ARCs were increased by 7.27% and 8.33%, respectively. The modified SiO2 ARCs possessed the advantages of the low manufacturing cost, good adhesion, superior antireflective performance and the feasible method for large area fabrication.