pH-Sensitive Chitosan-based Hydrogel Nanoparticles through Miniemulsion Polymerization Mediated by Peroxide Containing Macromonomer

Nanoemulsions for synthesis of biomedical nanocarriers

Nanoemulsions are kinetically stabilized emulsions with droplet sizes in the nanometer scale. These nanodroplets are able to confine spaces in which reactions of polymerization or precipitation can take place, leading to the formation of particles and capsules that can act as nanocarriers for biomedical applications. This review discusses the different possibilities of using nanoemulsions for preparing biomedical nanocarriers. According to the chemical nature, nanocarriers prepared in nanoemulsions are classified in polymeric, inorganic, or hybrid. The main synthetic strategies for each type are revised, including miniemulsion polymerization, nanoemulsion-solvent evaporation, spontaneous emulsification, sol-gel processes, and combination of different techniques to form multicomponent materials.

Cosolvents Impact on some Properties of the Solutions and the Films of Succinamide Chitosan

The article deals with the method of the medical purpose materials creation with the controlled physico-chemical and mechanical deformation properties on the basis of water-soluble derivative of amino polysaccharide chitosan – succinamide chitosan. The essence of the method is the macromolecules aggregation processes regulation in the initial solutions by the injection of organic cosolvents – acetone and ethanol. It has been stated that in a mixed solvent succinamide chitosan molecules are not in the form of the isolated macromolecular balls but as the macromolecules interacting (aggregated) systems. It has been proved that the presence of cosolvents decreases the polymer macromolecule links capability to interact with an enzyme and increases physico-mechanical characteristics of the film materials.

Systematic evaluation of pH and thermoresponsive poly(n-isopropylacrylamide-chitosan-fluorescein) microgel

The interesting properties of stimuli-responsive polymers lead to a wide range of possibilities in design and engineering of functional material for the biomedical application. A systematic approach focused on the evaluation of the physical properties of multiresponse (pH and temperature) PNIPAM was reported in this work. The effect of three different molar ratios of poly(n-isopropylacrylamide): chitosan (1:49, 1:99 and 1:198) were evaluated and labeled correspondingly as PC1F, PC2F, and PC3F. An increase in the lower critical solution temperature (LCST) of sample PC1F (34°C) was observed by differential scanning calorimetry (DSC). The presence of low molecular weight chitosan (LMWC) full-interpenetrating polymer (Full-IPN) segments in poly(n-isopropylacrylamide) was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The hydrogel’s water capture was analyzed by two models of swelling, the power law model and a model that considers the relaxation of polymeric chains of the hydrogel, finding good correlations with experimental data in both cases. Sample PC3F resulted with higher swellability, increasing the weight of the hydrogel around seven times. Hydrogel pH-sensibility was confirmed placing the samples at different pH environments, with an apparent increase in swellability for acidic conditions, confirming the highest swellability for sample PC3F, due to hydrogen bonds boosted by chitosan high molar ratio. Based on these results, the hydrogel obtained has potential as a thermo-pH triggered hydrogel in drug delivery applications.