Drug Delivery from Stimuli-Responsive Poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide)/Chitosan Core/Shell Nanohydrogels

Abstract

The synthesis of stimulus-responsive poly(N-isopropyl acrylamide-co-N-isopropyl methacrylamide)/chitosan core/shell nanohydrogels made by batch emulsion polymerization in the presence of chitosan (CS) micelles is reported. The ratio of monomers required to obtain copolymers with a volume phase transition temperature (TVPT) in the range of the temperatures observed in the human body in response to an infection (38 to 40 °C) was estimated with the Fox equation. The conversion was determined by gravimetry; mean particle size, size distribution, and thermal response were measured by quasi-elastic light scattering (QLS). The core/shell structure was confirmed by TEM, and FTIR showed the presence of N-isopropyl acrilamide (NIPA), N-isopropyl methacrylamide (NIPMA), and CS in the nanohydrogels. The nanohydrogels were loaded with the drug doxycycline hyclate, and their release kinetic profile was determined at pH 2.0 and 7.4 at their volume phase transition temperatures (TVPT). A higher amount of drug was released at acidic pH. Some mathematical models described in the literature were used to fit the experimental drug release data.

Deswelling Mechanisms of PNIPAM Grafted in Nanochannels: A Molecular Dynamics Simulation Study

“…The NIPAM/ NIPMAM/chitosan core−shell nanohydrogels were synthesized by intermittent emulsion polymerization in the presence of chitosan micelles. 33 This synthesis method confirmed the successful incorporation of doxycycline hydrochloride into the nanohydrogels and exhibited significant drug release at acidic pH levels.…”

“…The prepared temperature-sensitive gel was found to possess exceptional transparency and barrier properties through a process of comparison and screening. The NIPAM/NIPMAM/chitosan core–shell nanohydrogels were synthesized by intermittent emulsion polymerization in the presence of chitosan micelles . This synthesis method confirmed the successful incorporation of doxycycline hydrochloride into the nanohydrogels and exhibited significant drug release at acidic pH levels.…”

Chitosan-Based Smart Biomaterials for Biomedical Applications: Progress and Perspectives

“…An injectable hydrogel is currently being developed as a minimally invasive alternative subcutaneous route for drug delivery. , A smart injectable hydrogel uses thermal stimulation from temperature changes from the outside environment to the inside body, which will affect the swelling habits. This happens because temperature greatly affects their polymer–polymer and polymer–water interactions.…”

Recent Advances in Stimuli-Responsive Doxorubicin Delivery Systems for Liver Cancer Therapy

“…One of the most closely studied stimuli of controlled release systems is temperature. Temperature-sensitive polymers are used in order to obtain this responsive DDS, for different biomedical applications, such as temperature-sensitive gels, liposomes, micelles, colloidal particles, mRNA recovery, and gene delivery [ 112 , 113 , 114 ]. These thermosensitive polymers are able to release the encapsulated active substance even at small temperature variations.…”