Influencing Factors and Stimulus-Sensitivity of Chitosan/Polymethacrylic Acid (CS/PMAA) Nanogels as Nanocarriers

Nanogel, nanosized hydrogel, can contribute to biomedical and pharmaceutical, especially in drug delivery, due to its enthralling properties. Small size, large surface area, hydrophilicity, and stimulus responsiveness of nanogel ameliorate tissue penetration, drug loading capacity, and targeted drug delivery. The current study prepared nanosized, pH-sensitive, biocompatible, and stable chitosan/polymethacrylic acid (CS/PMAA) based nanogels using MBA as a crosslinker and APS as an initiator. FTIR confirmed the reaction between functional groups to synthesize nanogels sufficiently in a spherical shape, as affirmed by a FESEM. DLS data revealed nanosized particles with a size range of 70–170 nm and a range of 6–13 for polydispersity index (PDI). A study showed that 2% of MBA crosslinker is sufficient to achieve the desired crosslinking in 60 minutes reaction time (RT) with nanogel size ~ 92 nm. Increasing RT from 30 to 80 minutes during nanogel synthesis demonstrated a decrease in nanogel sizes from 186–73 nm. Synthesized nanogels have shown pH sensitivity (stimuli responsiveness) in acidic and alkaline mediums with an increase in particle size in pH-2 (~144 nm) and pH-8 (~280 nm) compared to intermediate pHs. The pH sensitivity of nanogels by changing the size per the suspended medium's pH is crucial for prolonged systemic circulation and targeted drug delivery. Moreover, nanogels have shown good colloidal stability with zeta potential (ZP) +28 mv in acidic and −38 mv alkaline mediums. DSC and XRD results demonstrated thermal stability and amorphous morphology of nanogels, respectively. BET surface analysis revealed the surface area of nanogels in the range of 65–68 cm2/g with an average pore size of 28–32 nm. In-vitro cytotoxicity in the L-929 cell line by MTT assay established the cell viability (>70%) after 24 hours of incubation, substantiating the non-toxicity and biocompatibility of nanogels as nanocarriers for drug delivery.