Other properties of the chitosan nanoparticles to notice are particle size and surface charge and their effect on mucosal surfaces and drug release profiles. According to research conducted by Warsito and Agustiani in 2021, it was evident that smaller particle size can entrap higher concentration of therapeutic agents, improve drug stability and its bioavailability, and provide sustained delivery. Tsai reported 40 that mixing procedures also had an effect on the optimum temperature to obtain small CNPs. In the CNPs produced by mechanical shearing at 1000 rpm, the best temperature to produce the smallest CNPs was 45 °C (145 nm), followed by 4°C (150 nm) and 25 °C (163 nm). However, it may be because the larger CNPs were removed during centrifugation. Thus, the smaller CNPs remained than the other CNPs formed at the temperature of 4 °C or from 25 °C. For the surface charge of the chitosan, the positive charge of chitosan enables it to attach to cells efficiently, increasing the probability of cellular uptake. Chitosan NPs are taken up by cells via different pathways and escape endosomal degradation due to the proton sponge effect. Hence, it can be concluded that the positive charge is advantageous for the chitosan NPs to be absorbed and assimilated in the human body.