RESUMO
Nanogels, or nanostructured hydrogels, are one of the most interesting materials in biomedical engineering. Nanogels are widely used in medical applications, such as in cancer therapy, targeted delivery of proteins, genes and DNAs, and scaffolds in tissue regeneration. One salient feature of nanogels is their tunable responsiveness to external stimuli. In this review, thermosensitive nanogels are discussed, with a focus on moieties in their chemical structure which are responsible for thermosensitivity. These thermosensitive moieties can be classified into four groups, namely, polymers bearing amide groups, ether groups, vinyl ether groups and hydrophilic polymers bearing hydrophobic groups. These novel thermoresponsive nanogels provide effective drug delivery systems and tissue regeneration constructs for treating patients in many clinical applications, such as targeted, sustained and controlled release.
RESUMO
Poly (l-lactide)-graft-chondroitin sulfate (PLLA-g-CS) copolymers were synthesized with different l-lactide contents via ring-opening polymerization. Chemical structure of the synthesized copolymers was confirmed by FTIR and HNMR analyses. The degree of polymerization and substitution of PLLA was found to be 0.56 and 2.98, respectively. Nisin was loaded in PLLA-g-CS nanogels at 37 and 42 °C. The hydrodynamic radius of the nanogels was 181 and 399 nm, respectively. The release profile was studied at two different temperatures and pHs over 7 days. The results indicated a variation of the cumulative release of nisin from 25 to 98% depending on the pH and temperature of release media. Cytotoxicity test of nisin loaded nanogels on human dermis fibroblast cells, confirmed no toxic effect. Finally, Antimicrobial activity of the nanogel was evaluated against Staphylococcus aureus and Escherichia coli bacteria. Overall, this study indicated that the dual responsive nanocarrier could potentially be used for infection therapeutic applications.
