Immobilization of Bovine Serum Albumin onto Porous Poly(vinylpyrrolidone)-Modified Silicas

Optical Properties and Antimicrobial Activity of Si/PVP Hybrid Material Combined with Antibiotics

Silica-poly (vinylpyrrolidone) hybrid material was prepared using the sol-gel method. Tetramethyl ortosilane (TMOS) was used as a silica precursor. XRD analysis established that the as-prepared material is amorphous. The morphological structure of the final product was determined by the incorporated PVP. The UV-Vis analysis showed that the obtained hybrid exhibited absorption in the ultraviolet range. The antimicrobial activity of the SiO2/15PVP hybrid material was tested on Staphylococcus epidermidis ATCC 14990, Salmonella typhimurium ATCC BAA-2162, Candida albicans, and Saccharomyces cerevisiae in combination with the following antibiotics: Vancomycin for Gram-positive bacteria, Ciprofloxacin for Gram-negative bacteria, and Nystatin for yeast. The results confirmed a concentration-dependent synergistic effect of the antibiotic in combination with the TM15/PVP hybrid particles, especially at their highest concentration of 100 mg/mL on Gram-positive bacteria and for the Gram-negative Salmonella. On Candida albicans ATCC 18804 and Saccharomyces cerevisiae CCY 21-6-3, the effect was synergistic again, and a fungicidal effect was observed at 6.25 and 1.50 mg/mL for the antibiotic concentration and concentrations of hybrid material at 100 mg/mL. The toxicity on Daphnia magna was also tested. The registered prooxidant activity of SiO2/15PVP shows possible applications at very low concentrations. The obtained results demonstrate the possibility of clinical implementations of the newly synthesized hybrid material.

Tranexamic acid loaded in a physically crosslinked trilaminate dressing for local hemorrhage control: Preparation, characterization, and in-vivo assessment using two different animal models

This work aimed at formulating a trilaminate dressing loaded with tranexamic acid. It consisted of a layer of 3 % sodium hyaluronate to initiate hemostasis. It was followed by a mixed porous layer of 5 % polyvinyl alcohol and 2 % kappa-carrageenan. This layer acted as a drug reservoir that controlled its release. The third layer was 5 % ethyl cellulose backing layer for unidirectional release of tranexamic acid towards the wound. The 3 layers were physically crosslinked by hydrogen bonding as confirmed by Infrared spectroscopy. Swelling and release studies were performed, and results proposed that increasing number of layers decreased swelling properties and sustained release of tranexamic acid for 8 h. In vitro blood coagulation study was performed using human blood and showed that the dressing significantly decreased coagulation time by 70.5 % compared to the negative control. In vivo hemostatic activity was evaluated using tail amputation model in Wistar rats. Statistical analysis showed the dressing could stop bleeding in a punctured artery of the rat tail faster than the negative control by 59 %. Cranial bone defect model in New Zealand rabbits was performed to check for bone hemostasis and showed significant decrease in the hemostatic time by 80 % compared to the control.

Continuous Patterning of Silver Nanowire-Polyvinylpyrrolidone Composite Transparent Conductive Film by a Roll-to-Roll Selective Calendering Process

The roll-to-roll (R2R) continuous patterning of silver nanowire-polyvinylpyrrolidone (Ag NW-PVP) composite transparent conductive film (cTCF) is demonstrated in this work by means of slot-die coating followed by selective calendering. The Ag NWs were synthesized by the polyol method, and adequately washed to leave an appropriate amount of PVP to act as a capping agent and dispersant. The as-coated Ag NW-PVP composite film had low electronic conductivity due to the lack of percolation path, which was greatly improved by the calendering process. Moreover, the dispersion of Ag NWs was analyzed with addition of PVP in terms of density and molecular weight. The excellent dispersion led to uniform distribution of Ag NWs in a cTCF. The continuous patterning was conducted using an embossed pattern roll to perform selective calendering. To evaluate the capability of the calendering process, various line widths and spacing patterns were investigated. The minimum pattern dimensions achievable were determined to be a line width of 0.1 mm and a line spacing of 1 mm. Finally, continuous patterning using selective calendering was applied to the fabrication of a flexible heater and a resistive touch sensing panel as flexible electronic devices to demonstrate its versatility.

Layer-by-layer films of polysaccharides modified with poly(N-vinylpyrrolidone) and poly(vinyl alcohol)

N-grafted copolymers of chitosan (460 kDa) with poly(N-vinylpyrrolidone) (2.4 kDa) or poly(vinyl alcohol) (2.0 ​kDa) as side chains were synthesized. Depending on the polymer-to-chitosan mass ratio the degree of amino group substitution with side chains in chitosan backbone was varied in the range of 0.01-0.33. Layer-by-layer films consisted of copolymers and dextran sulfate as polyanion were obtained. Thickness, hydrophilicity, and morphology of the films were investigated using QCM, UV-vis spectrophotometry, AFM, and contact angle measurements. The obtained films show enhanced protein-repellent properties in fetal bovine serum medium. The mass of adsorbed proteins on LbL films based on copolymer with a degree of substitution of 0.2 decreases by 50 ​% compared to unmodified chitosan. Protein-repellent properties of copolymer-based films are common for LbL films of grafted chitosan copolymers and depend on hydrophilic side chain density on the surface.

PVP Surface-protected silica coated iron oxide nanoparticles for MR imaging application

This paper proposed an engineered mesoporous silica-coated Fe₃O₄ nanoparticle, PVPMSFe, prepared by a sol-gel/surface-protected etching mechanism as an MRI T2 contrast agent. To this end, the structural characterization of the nanocomposite was performed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, VSM, thermogravimetric analysis (TGA), TEM, FESEM, and energy-dispersive X-ray scanning electron microscopy (EDS). The findings show that the synthesized nanocomposite has a mesoporous structure with an average particle size of 11.8 nm and excellent magnetization properties. The biocompatibility of PVPMSFe was investigated by MTT assay and hemolysis assay of red blood cells and the results indicate that PVPMSFe has favorable biocompatibility. Besides, the effect of PVPMSFe was assessed with MRI relaxivity measurement (T2 signal). Regarding the in vitro MRI relaxivity measurements outputs (r₂=144.4), PVPMSFe can attenuate the T2 signal of MRI, perfectly which makes it an efficient T2 contrast agent.

Experimental evaluation of oil recovery mechanism using a variety of surface-modified silica nanoparticles: Role of in-situ surface-modification in oil-wet system

Recent developments propose renewed use of surface-modified nanoparticles (NPs) for enhanced oil recovery (EOR) due to improved stability and reduced porous media retention. The enhanced surface properties render the nanoparticles more suitable compared to bare nanoparticles, for increasing the displacement efficiency of waterflooding. However, the EOR mechanisms using NPs are still not well established. This work investigates the effect of in-situ surface-modified silica nanoparticles (SiO₂ NPs) on interfacial tension (IFT) and wettability behavior as a prevailing oil recovery mechanism. For this purpose, the nanoparticles have been synthesized via a one-step sol-gel method using surface-modification agents, including Triton X-100 (non-ionic surfactant) and polyethylene glycol (polymer), and characterized using various techniques. These results exhibit the well-defined spherical particles, particularly in the presence of Triton X-100 (TX-100), with particle diameter between 13 to 27 nm. To this end, SiO₂ nanofluids were formed by dispersing nanoparticles (0.05 wt.%, 0.075 wt.%, 0.1 wt.%, and 0.2 wt.%) in 3 wt.% NaCl to study the impact of surface functionalization on the stability of the nanoparticle suspension. The optimal stability conditions were obtained at 0.1 wt.% SiO₂ NPs at a basic pH of 10 and 9.5 for TX-100/ SiO₂ and PEG/SiO nanofluids, respectively. Finally, the surface-treated SiO₂ nanoparticles were found to change the wettability of treated (oil-wet) surface into water-wet by altering the contact angle from 130° to 78° (in case of TX-100/SiO₂) measured against glass surface representing carbonate reservoir rock. IFT results also reveal that the surfactant treatment greatly reduced the oil-water IFT by 30%, compared to other applied NPs. These experimental results suggest that the use of surface-modified SiO₂ nanoparticles could facilitate the displacement efficiency by reducing IFT and altering the wettability of carbonate reservoir towards water-wet, which is attributed to more homogeneity and better dispersion of surface-treated silica NPs compared to bare-silica NPs.

A multifunctional nanocomposite spray dressing of Kappa-carrageenan-polydopamine modified ZnO/L-glutamic acid for diabetic wounds

Sprayable bioadhesives with exceptional properties were developed for application in wound healing. In this study, a visible light-crosslinkable nanocomposite bioadhesive hydrogel with multifunctional properties was proposed. While methacrylated Kappa-carrageenan (KaMA), mimicking the natural glycosaminoglycan was applied as the hydrogel matrix, various concentrations of polydopamine modified ZnO (ZnO/PD) nanoparticles (0, 0.5, 1 and 2 wt%) was loaded in it to improve its mechanical, antibacterial and cellular properties. Moreover, L-glutamic acid was incorporated in the nanocomposite hydrogel network to accelerate wound healing. The nanocomposite hydrogels revealed significant mechanical property and recovery ability, comparable elasticity with human skin and great adhesiveness. For instance, the tensile strength of KaMA hydrogel enhanced from 64.1 ± 10 to 80.3 ± 8 kPa and elongation jumped from 20 ± 4% to 61 ± 5% after incorporation of 1 wt% ZnO/PD nanoparticles. The nanocomposite hydrogels demonstrated effectual blood clotting ability and biocompatibility, >95% cell viability after 3 days of incubation. In vivo experiments also suggested that L-glutamic acid loaded nanocomposite hydrogel considerably accelerated wound healing with superior granulation tissue thickness than control in a full-thickness skin defect model. Taken together, this visible-light crosslinking nanocomposite hydrogel with significant properties could be used to spray on a wound area to eliminate wound infection and accelerate wound healing process.

Photo-immobilization of proteins on carbons

The photofunctionalization of three different carbons with two proteins was studied at room temperature. Water solutions of bovine serum albumin, BSA, and α-amylase, AA, were photolyzed at 21 °C in the presence of graphite microparticles (6.20 μm), MPG, graphene oxide, MPGO, and graphene oxide modified with SO₂, mMPGO. The insertion of BSA on carbon matrixes occurred with a deoxygenation reaction, most likely due to a dehydration step of a water molecule. XPS, TOC and TGA, showed that the BSA photo-insertion on MPG was highly efficient with 34.9% of the weight of MPG after photolysis, with an initial concentration of 1 g∙L^-1 of BSA. A high yield of AA photoinsertion on the carbons was also obtained. The calculated weight of AA inserted on MPG and MPGO after photolysis was 22.30% and 18.08%, respectively, with respect to the initial weight of carbon, when the initial concentration of AA was 60 mg∙L^-1. AA immobilized on MPG was active while the enzyme on MPGO showed a smaller activity, within the experimental error. Although a certain extent of denaturalization of both proteins was observed during photolysis, the molecular weight and composition changed very little during the photolysis, which would produce mainly conformational changes and isomerization reactions.

Enhancement of GAD Storage Stability with Immobilization on PDA-Coated Superparamagnetic Magnetite Nanoparticles

To improve the storage stability of glutamic acid decarboxylase (GAD), superparamagnetic magnetite (Fe3O4) nanoparticles were synthesized by co-precipitation method and coated with polydopamine (PDA) for GAD immobilization. Dynamic light scattering and transmission electron microscopy were used to determine size of the nanoparticles, which were approximately 10 nm, increasing to 15 nm after PDA-coating and to 20 nm upon GAD binding. Vibrational scanning measurements significantly represented the superparamagnetic behavior of the Fe3O4, and X-ray diffraction analysis confirmed that the crystalline structure before and after coating with PDA and the further immobilization of GAD remained the same. Thermogravimetric analysis and Fourier-transform infrared spectroscopy proved that the PDA-coating on Fe3O4 and further immobilization of GAD were successful. After immobilization, the enzyme can be used with a relative specific activity of 40.7% after five successive uses. The immobilized enzyme retained relative specific activity of about 50.5% after 15 days of storage at 4 °C, while free enzyme showed no relative specific activity after two days of storage. The GAD immobilization on PDA-coated magnetite nanoparticles was reported for the improvement of enzyme storage stability for the first time.

Porous Inorganic Carriers Based on Silica, Calcium Carbonate and Calcium Phosphate for Controlled/Modulated Drug Delivery: Fresh Outlook and Future Perspectives

Porous inorganic nanostructured materials are widely used nowadays as drug delivery carriers due to their adventurous features: suitable architecture, large surface area and stability in the biological fluids. Among the different types of inorganic porous materials, silica, calcium carbonate, and calcium phosphate have received significant attention in the last decade. The use of porous inorganic materials as drug carriers for cancer therapy, gene delivery etc. has the potential to improve the life expectancy of the patients affected by the disease. The main goal of this review is to provide general information on the current state of the art of synthesis of the inorganic porous particles based on silica, calcium carbonate and calcium phosphate. Special focus is dedicated to the loading capacity, controllable release of drugs under internal biological stimuli (e.g., pH, redox, enzymes) and external noninvasive stimuli (e.g., light, magnetic field, and ultrasound). Moreover, the diverse compounds to deliver with silica, calcium carbonate and calcium phosphate particles, ranging from the commercial drugs to genetic materials are also discussed.

Novel amphiphilic polyvinylpyrrolidone functionalized silicone particles as carrier for low-cost lipase immobilization

The high catalytic activity, specificity and stability of immobilized lipase have been attracting great interest. How to reduce the cost of support materials has always been a hot topic in this field. Herein, for the development of low-cost immobilized lipase, we demonstrate an amphiphilic polyvinylpyrrolidone (PVP) grafted on silicone particle (SP) surface materials (SP-PVP) with a rational design based on interfacial activation and solution polymerization. Meanwhile, hydrophilic pristine SP and hydrophobic polystyrene-corded silicone particles (SP-Pst) were also prepared for lipase immobilization. SP-PVP was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetry. Our results indicated that the lipase loading amount on the SP-PVP composites was about 215 mg of protein per gram. In the activity assay, the immobilized lipase SP-PVP@CRL exhibited higher catalysis activity and better thermostability and reusability than SP@CRL and SP-Pst@CRL. The immobilized lipase retained more than 54% of its initial activity after 10 times of re-use and approximately trended to a steady rate in the following cycles. By introducing the interesting amphiphilic polymer to this cheap and easily obtained SP surface, the relative performance of the immobilized lipase can be significantly improved, facilitating interactions between the low-cost support materials and lipase.

Controlling adsorption and passivation properties of bovine serum albumin on silica surfaces by ionic strength modulation and cross-linking

Understanding the physicochemical factors that influence protein adsorption onto solid supports holds wide relevance for fundamental insights into protein structure and function as well as for applications such as surface passivation.