Chitosan gel sheet containing drug carriers with controllable drug-release properties

Chitin Nanowhisker/Gold Nanocluster Hybrids with an Excellent Dispersion Stability via Poly(ethylene glycol) Grafting

Hybrid nanoparticles composed of chitin nanowhiskers (ChNWs) and gold nanoclusters (AuNCs) having an improved stability were prepared. The grafting of monomethoxypoly(ethylene glycol) (mPEG) and subsequent surface adsorption of AuNCs enabled the steric stabilization of ChNW/AuNC hybrids. mPEGs with terminal formyl groups and diethylacetal protecting groups were grafted via in situ deprotection and reductive amination with the surface amino groups (SAGs) of ChNWs. The treatment of chitin with a 30% sodium hydroxide solution improved the SAG contents of the ChNWs obtained from acid hydrolysis, resulting in an enhancement in mPEG grafting. The obtained sterically stabilized ChNW/AuNC hybrids exhibited remarkable dispersion stability at higher AuNC and electrolyte concentrations.

Temperature-Responsive Polysaccharide Microparticles Containing Nanoparticles: Release of Multiple Cationic/Anionic Compounds

Most drug carriers used in pulmonary administration are microparticles with diameters over 1 µm. Only a few examples involving nanoparticles have been reported because such small particles are readily exhaled. Consequently, the development of microparticles capable of encapsulating nanoparticles and a wide range of compounds for pulmonary drug-delivery applications is an important objective. In this study, we investigated the development of polysaccharide microparticles containing nanoparticles for the temperature-responsive and two-step release of inclusions. The prepared microparticles containing nanoparticles can release two differently charged compounds in a stepwise manner. The particles have two different drug release pathways: one is the release of nanoparticle inclusions from the nanoparticles and the other is the release of microparticle inclusions during microparticle collapse. The nanoparticles can be efficiently delivered deep into the lungs and a wide range of compounds are released in a charge-independent manner, owing to the suitable roughness of the microparticle surface. These polysaccharide microparticles containing nanoparticles are expected to be used as temperature-responsive drug carriers, not only for pulmonary administration but also for various administration routes, including transpulmonary, intramuscular, and transdermal routes, that can release multiple drugs in a controlled manner.

Chitosan hydrogels incorporating colloids for sustained drug delivery

In today's biomedical research, a huge effort is being made towards the development of efficient drug delivery systems, achieving sustainable and controlled delivery of drugs. Chitosan (CS) hydrogels are high water content materials with very relevant biological properties to that purpose. Their use for a local and delayed delivery has already been demonstrated for a wide variety of therapeutic agents. One relatively recent strategy to improve these CS-based systems consists in the insertion of colloids, embedding drugs, within their three-dimensional matrix. This provides a second barrier to the diffusion of drugs through the system, and allows to better control their release. The main objective of this review is to report the many existing complex systems composed of CS hydrogels embedding different types of colloids used as drug delivery devices to delay the release of drugs. The various biomedical applications of such final systems are also detailed in this review.

Nanoencapsulation of hydroxytyrosol in chitosan crosslinked with sodium bisulfate tandem ultrasonication: Techno-characterization, release and antiproliferative properties

This research includes production of chitosan nanocapsules through ionic gelation with sodium bisulfate for nanoencapsulation of hydroxytyrosol (HT) using ultrasonication in tandem. The resulting nanocapsules encapsulating HT were analyzed for particle size, ζ-potential, packaging characteristics, FESEM, ATR-FTIR, XRD, DSC, in vitro release, antioxidant potential and antiproliferative properties. The nanocapsules (size 119.50-365.21 nm) were spherical to irregular shaped with positive ζ-potential (17.50-18.09 mV). The encapsulation efficiency of 5 mg/g HT (HTS1) and 20 mg/g HT (HTS2) was 77.13% and 56.30%, respectively. The nanocapsules were amorphous in nature with 12.34% to 15.48% crystallinity and crystallite size between 20 nm and 27 nm. Formation of nanocapsules resulted in increasing the glass transition temperature. HTS2 delivered 67.12% HT (HTS1 58.89%) at the end of the simulated gastrointestinal digestion. The nanoencapsulated HT showed higher antioxidant and antiproliferative (against A549 and MDA-MB-231 cancer cell lines) properties than the free HT.

PEG-interpenetrated genipin-crosslinked dual-sensitive hydrogel/nanostructured lipid carrier compound formulation for topical drug administration

PEG-interpenetrated dual-sensitive hydrogels that load nano lipid carrier (NLC) were researched and developed for topical drug administration. Natural antioxidant α-lipoic acid (ALA) was selected as our model drug. The α-lipoic acid (ALA) nano lipid carrier was successfully prepared by hot melt emulsification and ultrasonic dispersion method, and the physicochemical properties of the nano lipid carrier were investigated, including morphology, particle distribution, polydispersity coefficient, zeta potential and encapsulation efficiency. Carboxymethyl chitosan and poloxamer 407 contributed to pH- and temperature-sensitive properties in the hydrogel, respectively. Natural non-toxic cross-linking agent genipin reacted with carboxymethyl chitosan to form the hydrogel. Poly ethylene glycol (PEG), a polymer compound with good water solubility and biocompatibility, interpenetrated the hydrogel and influenced the mechanical strength and drug release behaviour. FI-IR test verified the successful synthesis of the hydrogel. The rheological parameters indicated that the mechanical strength of the hydrogel was positively correlated with the amount of PEG, and the in vitro dissolution profiles demonstrated that the increasement of PEG could accelerate the drug release rate. The compatibility of the drug delivery system was verified with cells and mice model. Topical delivery of ALA in solution, NLC and NLC-gel was investigated in-vitro.

Marine Polysaccharides for Wound Dressings Application: An Overview

Wound dressings have become a crucial treatment for wound healing due to their convenience, low cost, and prolonged wound management. As cutting-edge biomaterials, marine polysaccharides are divided from most marine organisms. It possesses various bioactivities, which allowing them to be processed into various forms of wound dressings. Therefore, a comprehensive understanding of the application of marine polysaccharides in wound dressings is particularly important for the studies of wound therapy. In this review, we first introduce the wound healing process and describe the characteristics of modern commonly used dressings. Then, the properties of various marine polysaccharides and their application in wound dressing development are outlined. Finally, strategies for developing and enhancing marine polysaccharide wound dressings are described, and an outlook of these dressings is given. The diverse bioactivities of marine polysaccharides including antibacterial, anti-inflammatory, haemostatic properties, etc., providing excellent wound management and accelerate wound healing. Meanwhile, these biomaterials have higher biocompatibility and biodegradability compared to synthetic ones. On the other hand, marine polysaccharides can be combined with copolymers and active substances to prepare various forms of dressings. Among them, emerging types of dressings such as nanofibers, smart hydrogels and injectable hydrogels are at the research frontier of their development. Therefore, marine polysaccharides are essential materials in wound dressings fabrication and have a promising future.

Quaternized Chitosan Nanoparticles in Vaccine Applications

Different natural and synthetic biodegradable polymers have been used in vaccine formulations as adjuvant and delivery system but have faced various limitations. Chitosan is a new delivery system with the potential to improve development of nano vaccines and drugs. However, chitosan is only soluble in acidic solutions of low concentration inorganic acids such as dilute acetic acid and dilute hydrochloric acid and in pure organic solvents, which greatly limits its application. Chemical modification of chitosan is an important way to improve its weak solubility. Quaternized chitosan not only retains the excellent properties of chitosan, but also improves its water solubility for a wider application. Recently, quaternized chitosan nanoparticles have been widely used in biomedical field. This review focuses on some quaternized chitosan nanoparticles, and points out the advantages and research direction of quaternized chitosan nanoparticles. As shown by the applications of quaternized chitosan nanoparticles as adjuvant and delivery carrier in vaccines, quaternized chitosan nanoparticles have promising potential in application for the development of nano vaccines in the future.

PLA- and PLA/PLGA-Emulsion Composite Biomaterial Sheets for the Controllable Sustained Release of Hydrophilic Compounds

In the present study, by spin-coating a solution containing w/o (water-in-oil) emulsions and hydrophobic polymers, we obtained sheets possessing uniformly dispersed w/o emulsions. We performed release experiments for more than 100 days and clarified the effects of the number of layers, the sheet-forming polymers (polylactide (PLA), poly(lactic-co-glycolic acid (PLGA)), the ratio of organic solvent to water, and the composition of block copolymers on the release properties of the sheets. For a variety of sheets, we successfully achieved the sustained release of compounds from the sheets for 100–150 days. The sustained-release of compounds occurred because the compounds had to diffuse into polymer networks after their release from the emulsions. Interestingly, we observed an inflection point in the release profiles at around 50 days; that is, the sheet exhibited a “two-step” release behavior. The results obtained in the present study provide strong evidence for the future possibility of the time-programmed release of multiple compounds from sheets.