Antibacterial nanocellulose membranes coated with silver nanoparticles for oil/water emulsions separation.

The superhydrophilic/underwater superoleophobic nanocellulose-based membranes show great potential in oil/water emulsion separation. However, nanocellulose composed of polysaccharides inevitably suffered from bacterial erosion during use or storage, resulting in structural damage or reduced separation efficiency. In this work, silver nanoparticles (AgNPs) as effective bactericidal materials are uniformly deposited on tunicate cellulose nanocrystals (TCNCs) by in situ hydrothermal reduction of silver nitrate. TCNCs not only act as reducing agents for silver ions, but also work as dispersant and stabilizers of AgNPs. Nanocomposite membranes are fabricated by vacuum-assisted filtrating of AgNPs@TCNC suspension, which exhibit nanoporous structure, superhydrophilicity, and underwater superoleophobicity. These membranes could efficiently separate oil/water microemulsion with water flux (>324 L m-2 h-1 bar-1) and oil rejection (>99%). Importantly, these membranes show excellent antibacterial efficacy against E. coli and S. aureus, benefiting to their long-term use and storage.

Development and characterization of a biomimetic coating for percutaneous devices.

Percutaneous osseointegrated prosthetics (POP), which consist of a metallic post attached to the bone that extends outward through the skin to connect to an external prosthesis, have become a clinically relevant option to replace the typical socket-residual limb connection. POP devices offer several advantages such as mechanical off-loading of soft tissues, direct force transfer to the musculoskeletal system, greater proprioception, and overall improvement in limb kinesis compared to a socket system. However, POP devices create several challenges including epidermal downgrowth, increased infection risk, and mechanical tearing at the skin-implant interface. To address these issues, biomimetic surfaces and coatings have been developed in an attempt to create an infection-free and cohesive interface between POP devices and skin. The fingernail is a prime example of a natural system with a skin interface that is both mechanically and biologically stable. Exploiting keratins' previously demonstrated tissue compatibility and creating a biomimetic coating for POP devices that can imitate the human fingernail, and demonstrating its ability to promote a stable interface with skin tissue is the goal of this work. Silane coupling aided in producing a coating on titanium substrates consisting of human keratin proteins. Several combinations of silane and keratin derivatives were investigated, and in general showed a nano-scale coating thickness that supported skin cell (i.e. fibroblast and keratinocyte) adhesion. Initial enzyme-mediated degradation resistance was also demonstrated, but the coatings appeared to degrade at long time periods. Importantly, keratinocytes showed a stable phenotype with no indication of wound healing-like activity. These data provide justification to further explore keratin biomaterials for POP coatings that may stabilize the implant-skin interface.

ß-Glucan as an encapsulating agent: Effect on probiotic survival in simulated gastrointestinal tract.

Three strains of probiotics Lactobacillus casei, Lactobacillus brevis, and Lactobacillus plantarum were encapsulated in ß-glucan matrix using emulsion technique. Further the encapsulated cells were studied for their tolerance in simulated gastrointestinal conditions and its storage stability. The average encapsulation efficiency of ß-glucan-probiotic beads was found to be 74.01%. The surface morphology of ß-glucan containing bacteria was studied using SEM. The noteworthy absorptions in the FT-IR spectra between 1300-900 cm(-1) and 2918-2925 cm(-1) corresponds to the presence of bacteria into the glucan matrix. Also, the thermal stability of ß-glucan was evaluated using Differential Scanning Calorimeter. The efficiency of ß-glucan in protecting the surviability of probiotic cells under simulated gastrointestinal conditions was studied. Results revealed significant (p<0.05) improvement to tolerance when the encapsulated cells were subjected to stresses like low pH, heat treatment, simulated intestinal conditions and storage.

In-vitro evaluation of khaya and albizia gums as compression coatings for drug targeting to the colon.

Khaya and albizia gums were evaluated as compression coatings for target drug delivery to the colon using indometacin (a water insoluble drug) and paracetamol (a water soluble drug) as model drugs. The core tablets were compression-coated with 300 and 400 mg of 100% khaya gum, 100% albizia gum and a mixture of khaya and albizia gum (1:1). Drug release studies were carried out in 0.1(M) HCl (pH 1.2) for 2 h, Sorensen's buffer (pH 7.4) for 3 h and then in phosphate-buffered saline (pH 6.8) or in simulated colonic fluid for the rest of the experiment to mimic the physiological conditions from the mouth to colon. The results indicated that khaya and albizia gums were capable of protecting the core tablet in the physiological environment of the stomach and small intestine, with albizia gum showing greater ability than khaya gum. The release from tablets coated with the mixture of khaya and albizia gums was midway between the two individual gums, indicating that there was no interaction between the gums. Studies carried out using rat caecal matter in phosphate-buffered saline at pH 6.8 (simulated colonic fluid) showed that the gums were susceptible to degradation by the colonic bacterial enzymes, leading to release of the drug. The results demonstrate that khaya gum and albizia gum have potential for drug targeting to the colon.

Preparation and modification of N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride nanoparticle as a protein carrier.

N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is water-soluble derivative of chitosan (CS), synthesized by the reaction between glycidyl-trimethyl-ammonium chloride and CS. HTCC nanoparticles have been formed based on ionic gelation process of HTCC and sodium tripolyphosphate (TPP). Bovine serum albumin (BSA), as a model protein drug, was incorporated into the HTCC nanoparticles. HTCC nanoparticles were 110-180 nm in size, and their encapsulation efficiency was up to 90%. In vitro release studies showed a burst effect and a slow and continuous release followed. Encapsulation efficiency was obviously increased with increase of initial BSA concentration. Increasing TPP concentration from 0.5 to 0.7 mg/ml promoted encapsulation efficiency from 46.7% to 90%, and delayed release. As for modified HTCC nanoparticles, adding polyethylene glycol (PEG) or sodium alginate obviously decreased the burst effect of BSA from 42% to 18%. Encapsulation efficiency was significantly reduced from 47.6% to 2% with increase of PEG from 1.0 to 20.0 mg/ml. Encapsulation efficiency was increased from 14.5% to 25.4% with increase of alginate from 0.3 to 1.0 mg/ml.

Chitin/PLGA blend microspheres as a biodegradable drug delivery system: a new delivery system for protein.

Novel chitin/PLGAs and chitin/PLA based microspheres were developed for the delivery of protein. These biodegradable microspheres were prepared by polymers blending and wet phase-inversion methods. The parameters such as selected non-solvents, temperature of water and ratio of polylactide to polyglycolide were adjusted to improve thermodynamic compatibility of individual polymer (chitin and PLGAs or chitin/PLA), which affects the hydration and degradation properties of the blend microspheres. Triphasic pattern of drug release model is observed from the release of protein from the chitin/PLGAs and chitin/PLA microspheres: the initially fast release (the first phase), the following slow release (the second phase) and the second burst release (the third phase). Formulations of the blends, which are based on the balance among the hydration rate of the chitin phase and degradation of chitin/PLA and PLGA phase, can lead to a controllable release of bovine serum albumin (BSA). In conclusion, such a chitin/PLGA 50/50 microsphere is novel and interesting, and may be used as a protein delivery system.

Preparation and characterization of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) microspheres for controlled release of paclitaxel.

Microspheres of a new kind of copolymer, poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA), are proposed in the present work for clinical administration of an antineoplastic drug paclitaxel with hypothesis that incorporation of a hydrophilic PEG segment within the hydrophobic PLA might facilitate the paclitaxel release. Paclitaxel-loaded PLA-PEG-PLA microspheres of various compositions were prepared by the solvent extraction/evaporation method. Characterization of the microspheres was then followed to examine the particle size and size distribution, the drug encapsulation efficiency, the colloidal stability, the surface chemistry, the surface and internal morphology, the drug physical state and its in vitro release behavior. The effects of polymer types, solvents and drug loading were investigated. It was found that in the microspheres the PEG segment was homogeneously distributed and caused porosity. Significantly faster release from PLA-PEG-PLA microspheres resulted in comparison with the PLGA counterpart. Incorporation of water-soluble solvent acetone in the organic solvent phase further increased the porosity of the PLA-PEG-PLA microspheres and facilitated the drug release. A total of 49.6% sustained release of paclitaxel within 1 month was achieved. Potentially, the presence of PEG on the surface of PLA-PEG-PLA microspheres could improve their biocompatibility. PLA-PEG-PLA microspheres could thus be promising for the clinical administration of highly hydrophobic antineoplastic drugs such as paclitaxel.

Evaluation of microbeads of calcium alginate as a fluidized bed medium for affinity chromatography of Aspergillus niger Pectinase.

Calcium alginate microbeads (212-425 microm) were prepared by spraying 2% (w/v) alginate solution into 1 M CaCl2 solution. The fluidization behavior of these beads was studied, and the bed expansion index and terminal velocity were found to be 4.3 and 1808 cm h(-1), respectively. Residence time distribution curves showed that the dispersion of the protein was much less with these microbeads than with conventionally prepared calcium alginate macrobeads when both kinds of beads were used for chromatography in a fluidized bed format. The fluidized bed of these beads was used for the purification of pectinase from a commercial preparation. The media performed well even with diluted feedstock; 90% activity recovery with 211-fold purification was observed.

Synthesis and characterization of silica-embedded iron oxide nanoparticles for magnetic resonance imaging.

In this communication, a conceptually new approach to the delivery of magnetic resonance imaging (MRI) contrast agents is presented. Our experiments demonstrate the feasibility of using silica-embedded iron oxide nanoparticles as contrast agents in magnetic resonance imaging, where a reduction in signal intensity (increased contrast) in the T2-weighted images is observed. The surface of these particles can be chemically modified by attachment of polyethylene glycol molecules, which are found to reduce nonspecific protein binding. The design of the nanoparticle is universal and flexible and allows for facile addition or interchange of its active components (i.e., MRI contrast agents and targeting moiety) with photodynamic dyes.

Antimicrobial and enzymatic antibrowning film used as coating for bamboo shoot quality improvement.

Edible films were prepared with varying proportion of alginate and starch in the ratio of 2:0(F1), 2:1(F2), 1:1(F3), 1:1.5(F4), 1:2(F5), 0:2(F6) with added carboxymethyl cellulose (15%, w/w of starch). The film F5 had superior barrier, mechanical and thermal properties over the other films. Water vapor permeability, moisture absorption, water solubility, breakage strength and elongation capacity of F5 film were reported as 1.21 × 10(-9)g/Pa h m, 9.37%, 40%, 977.3g and 14.62 mm respectively. However, surface characteristics showed the smooth and uniform film and thermal decomposition took place above 200 °C. The film forming solution of selected F5 film, added with antioxidant and antimicrobial extracts was coated on bamboo shoots and stored for 5 days. The film was successful in lowering the browning of bamboo shoots, and also successfully inhibited surface microbial load. Moreover, the moisture loss of coated shoot was less compared to uncoated.

Stabilization of plasma-polymerized allylamine films by ethanol extraction.

The effect of ethanol extraction on plasma-polymerized allylamine (PPAA) films was investigated by measuring their thickness change using surface plasmon resonance (SPR) spectroscopy and optical waveguide spectroscopy (OWS). It was found that much of the freshly deposited PPAA films is lost upon ethanol treatment. The decrease in PPAA thickness is related to the plasma input power, the monomer vapor pressure, and the thickness of the deposited films. Despite the relatively high loss in film thickness, the densities of the amine groups in the extracted PPAA are comparable to those of fresh films, as seen by Fourier transform infrared (FT-IR) spectroscopy. The results of this study are of specific importance with respect to the biomedical application of plasma-polymerized functional thin films, in which the stability of a plasma polymer in contact with aqueous media is essential.

Subtractive chromatography for purification and recovery of nano-bioproducts.

A novel polymer-coated adsorbent (subtractive adsorbent) has been manufactured and evaluated for the recovery of nanoparticle bioproducts. The core principle was to coat inert macroporous polymers (e.g. agarose) upon adsorbent beads of varied ligands. Here BSA nanoparticles, with an average nanoparticle diameter 95 nm, were fabricated and selected as feedstock for the demonstration of the principle. The adsorption of a mixture of fluorescently labelled BSA solution and BSA nanoparticles was investigated in a batch binding experiment upon polymer-coated Streamline DEAE and visualised by laser scanning confocal microscopy. The mechanistic design of such adsorbents and their basic application for the recovery of target nano-bioproducts from complex feedstock is strongly indicated.