Thermosensitive PNIPAM grafted alginate/chitosan PEC

Abstract

Smart biomaterial functionality such as controlled adhesion properties is crucial to limit strip-<>ff injuries. Among functional polymers, poly•N(isopropylacrylamide) (PNIPAM) allows surface properties to be changed depending on the temperature, with a transition of its properties that occurs around 32 •c, called the lower critical solution temperature (LCST). This transition is expected to modify surface interactions. Alginate and chitosan are bio compatible polymers commonly combined as polyelectrolyte complex (PEC) and are suitable for wound dressing applications. As a complex system, however, it is not so trivial to achieve an efficient functionalization. Herein, we elaborated a procedure to functional ize the surface of alginate/chitosan PECs without al tering their intrinsic properties. Fil R revealed that acidic treatment led to a partial decomplexation of the PECs. Therefore, while the N• Hydroxysuccinimide/N•(3-Dim eth ylaminopropyl}-N '-eth ylcarbodümide (N HS/EDC) cou pling usually requires an intermediate pH, we showed that a preliminary acidifi cation seemed to increase the surface grafting effi. ciency. Water contact angle increased fr om 51° to n•, showing that PNIPAM enhanced the surface hydro phobicity. The l.CST transition modified the interaction forces between PNIPAM and mode! surfaces: it revealed an unexpected thermosensitive behaviour as hydrophobie transition favoured interactions with hydrophilic surfaces. It was presumably due to PNIP AM/PEC substrate interactions. Finally, the surface modification did not affect the release properties of the PEC biomaterial.

Chitosan-Graft-Poly(N-Isopropylacrylamide)/PVA Cryogels as Carriers for Mucosal Delivery of Voriconazole

“…Chitosan has a highly regular structure consisting of β -(1→4) linked D-glucosamine repeating units with three reactive groups, giving many possibilities of functionalization. Among the various methods, graft modification is considered as a convenient and promising approach to expand the applicability and functionality of chitosan [2,3,4,5,6,7,8]. However, the conventional grafting techniques on chitosan do not give control on the side polymer chain lengths and composition, the number of grafting sites, and grafting percentage.…”

Surface modification of neurotrophin‐3 loaded PCL/chitosan nanofiber/net by alginate hydrogel microlayer for enhanced biocompatibility in neural tissue engineering

“…The first layer of the alginate hydrogel network structure coated the whole nanofibrous sheet, and in the second layer, alginate penetrated into the sheet and covered the PCL/chitosan nanofibers individually. The great swelling ability of fibers facilitated the infiltration of alginate into each PCL/chitosan nanofiber and caused electrostatic interaction between amine groups of chitosan and carboxyl groups of alginate 48 . This novel scaffold has created a more interconnected nanoporous layer that is vital to let nutrients diffuse to cells within the construct and take waste products out of the scaffold 49 .…”

Hydrophobization of hydrophilic alginate/chitosan PEC surfaces

“…The chemical modification strategy was based on previously reported studies 18 . Briefly, the hydroxyl groups of PCL and PLA cannot react easily with the carboxylate groups of alginate and consequently these have to be activated by EDC.…”

“…However, the properties of these potential biomaterials are also strongly dependent on their surface characteristics, given the fact that body/biomaterial interface is crucial for cell or protein interactions with the implant. We believe that alginate and chitosan PEC can be a useful platform, and have previously tailored its surface and thus functional properties by modifying its surface chemistry through the action of PNIPAM, a thermosensitive polymer, 17 and showed that interactions with inert surfaces, 18 cells and tissues 19 can be controlled.…”

“…However, it is no trivial matter covering highly hydrophilic PECs with such hydrophobic polymers, and preliminary assays showed that direct coating resulted in a non‐adhesive layer that delaminated in the early stages of use, for example, after immersion in aqueous environments. The aim of this study is to propose a quite simple way to overcome this problematic by performing a first graft of the hydrophobic polymer (PCL or PLA) prior to performing the coverage by drop casting 18 . The use of hexane diamine (HDA) and (EDA) as a linker was compared in order to optimize the method.…”