Borax Mediated Layer-by-Layer Self-Assembly of Neutral Poly(vinyl alcohol) and Chitosan

Abstract

We report a multilayer film of poly(vinyl alcohol) (PVA)-borate complex and chitosan by using a layer-by-layer approach. PVA is an uncharged polymer, but hydroxyl functional groups of PVA can be cross-linked by using borax as a cross-linking agent. As a result electrostatic charges and intra- and interchain cross-links are introduced in the PVA chain and provide physically cross-linked networks. The PVA-borate was then deposited on a flat substrate as well as on colloidal particles with chitosan as an oppositely charged polyelectrolyte. Quartz crystal microbalance, scanning electron microscopy, and atomic force microscopy were used to follow the growth of thin film on flat substrate. Analogous experiments were performed on melamine formaldehyde colloidal particles (3-3.5 microm) to quantify the process for the preparation of hollow microcapsules. Removal of the core in 0.1 N HCl results in hollow microcapsules. Characterization of microcapsules by transmission electron microscopy revealed formation of stable microcapsules. Further, self-assembly of PVA-borate/chitosan was loaded with the anticancer drug doxorubicin, and release rates were determined at different pH values to highlight the drug delivery potential of this system.

In vitro Antifungal Activity of Olive (Olea europaea) Leaf Extracts Loaded in Chitosan Nanoparticles

“…In recent years, an increased interest has been developed for natural polymers which have a versatility due to their chemical, physical and functional properties. The wide range of potential applications has led to their use in various fields of research, mainly in the biomedical, cosmetics, food and pharmaceuticals (Agnihotri et al, 2004;Manna and Patil, 2009). Chitosan (CS) has emerged as one of the most promising polymers for the formation of nanoparticles (NPs) (Kashyap et al, 2015), mainly due to its biodegradable and biocompatible properties, its moderate or lack of toxicity to animals and humans, and for its antimicrobial and antifungal activity (López-León et al, 2005;Zhou and Chen, 2008;Akamatsu et al, 2010).…”

Covalent Layer‐by‐Layer Assembly Using Reactive Polymers

“…Ding et al [105] have also demonstrated that multilayers assembled from poly(vinyl alcohol) (PVA) and poly(acrylamide-co-3-(acrylamido)phenylboronic acid) (Figure 15.15) disassemble at an accelerated rate on the addition of glucose. In both studies, disassembly was attributed to competitive interactions (e.g., boronate ester exchange) in the films on addition of small-molecule sugars, which resulted in a reduction of intrachain While these latter examples demonstrate the potential of this approach, we note that the chemistry of boronic acids can be complex, and the nature and extents of reactions between polyols and boronic acids can depend strongly on changes in pH, ionic strength, and the structure of the reactants [148][149][150]. As is also generally true for most other reaction platforms described above (with the possible exceptions of highly specific click-type reactions), the potential for side reactions and/or important contributions arising from other noncovalent interactions during or after film assembly should be borne in mind with respect to the further development of these covalent LbL approaches.…”

Nanostructures and Nanostructured Networks for Smart Drug Delivery

“…These capsules have a pH-dependent permeability that makes the loading of proteins as well as the control of the release possible. Successive layers of cross-linked PVP and chitosan have also been shown to be useful in preparing hollow microcapsules for pH-dependent release of doxorubicin [204]. Thin films that retain the drug at the pH of the stomach but release it at the weakly acid/neutral pH of the gut were obtained by alternate deposition of insulin and poly(vinyl sulfate), poly(acrylic acid), or dextran sulfate [205].…”