“…For the obtained materials such parameters as the degree of quaternization and/or the degree of substitution should be determined and their influence on the investigated biological properties tested, -the biological properties of chitin/chitosan materials used directly in biomedical applications (e.g., antimicrobial effects) could be different that observed for materials obtained after preparation of nanoparticles, microspheres, hydrogels, films, fibers or tablets, -considerable research efforts should be directed towards developing safe and efficient chitin/chitosan-based formulations. As an example, such factors as particle size requirement, the thermal and chemical stability of the active agent, reproducibility of the kinetic release profiles, stability of the final product and residual toxicity associated with the final product depends upon the methods of preparing chitosan-based micro/nanoparticulate drug delivery systems, -the influence of physicochemical properties apart from M W and DA on chitosan-based formulation affecting the delivery of DNA and siRNA [51] and on antimicrobial properties of chitin/chitosan materials [68][69][70][71][72][73][74][85][86][87][88]94,95,104,105] is the best known. For other biological properties our knowledge is still not sufficient, -chitin/chitosan properties are interrelated and many times they could influence the bioactivity in a conflicting manner, e.g., would healing properties and permeation enhancement properties are inevitably linked to other such as mucoadhesion and cytotoxicity.…”