Chitosan and Its Derivatives as Nanocarriers for Drug Delivery.

Chitosan (CS) occurs naturally as an alkaline polysaccharide and has been demonstrated to have several activities of a biological nature. Additionally, as CS chains have functional hydroxyl and amino groups that are active, their applications can be expanded by chemically or molecularly altering the molecules to incorporate new functional groups. Due to its outstanding qualities, including biodegradability, biocompatibility, non-toxicity, and accessibility, it has received significant interest in all areas of biomedicine and nanomaterials being extremely promising as drug nanocarrier. The last decades have produced a lot of interest in CS-based nanoparticles (CSNPs), with an increasing number of research papers from around 1500 in 2015 to almost 5000 in 2024. The degree of crosslinking, the particulate system's shape, size, and density, in addition to the drug's physical and chemical properties, all have a role in how the drug is transported and released from CSNPs. When creating potential drug delivery systems based on CSNPs, all these factors must be considered. In earlier, CSNPs were employed to enhance the pharmacotherapeutics, pharmacokinetics, and solubility properties of drugs. By investigating its positively charged characteristics and changeable functional groups, CS has evolved into a versatile drug delivery system. The drug release from CSNPs will definitely be influenced by various changes to the functional groups, charges, and polymer backbone. This review mainly discusses the most important results published in the last decade. Despite the promising advantages of CSNPs, challenges related to the translation into clinical stages remain and further in vitro and in vivo studies are mandatory.