Water soluble derivatives of chitin such as chitosan and nanochitin are used in various agricultural applications and have shown to have many benefits.
Chitin has shown to be an effective plant growth enhancer, as it can stimulate nutrient absorption and boost the activity of plant growth hormones. This process involves biostimulation facilitated by rhizobacteria known for promoting plant growth (PGPR). 
Chitin is also a good natural fertiliser, serving as an ingredient in fertiliser production and classified as an organic nitrogen fertiliser (Type C). Chitin and its derivatives possess unique qualities among carbohydrates, including a low C/N ratio and a significant nitrogen content. 
Enhances Immune Response
Chitin gives protective action indirectly by activating the immune defence mechanism of plants through eliciting activity . It also enhance the healing of tissues of wounded trees and shrubs. 
 J. K. Vessey, “Plant growth promoting rhizobacteria as biofertilizers,” Plant and Soil, vol. 255, no. 2, pp. 571–586, Aug. 2003, doi: 10.1023/A:1026037216893.
 J. L. Shamshina, A. Kelly, T. Oldham, and R. D. Rogers, ‘Agricultural uses of chitin polymers’, Environmental Chemistry Letters, vol. 18, no. 1, pp. 53–60, 2020.
 C. L. Velásquez and M. R. Pirela, ‘Biochemical aspects of the chitin fungicidal activity in agricultural uses’, Chitosan in the preservation of agricultural commodities, pp. 279–298, 2016.
 R. G. Sharp, ‘A review of the applications of chitin and its derivatives in agriculture to modify plant-microbial interactions and improve crop yields’, Agronomy, vol. 3, no. 4, pp. 757–793, 2013.
Chitin derivatives, such as chitosan and chitin nanomaterials, show promising potential for various biomedical applications.
 K. Shou et al., ‘Induction of mesenchymal stem cell differentiation in the absence of soluble inducer for cutaneous wound regeneration by a chitin nanofiber‐based hydrogel’, Journal of tissue engineering and regenerative medicine, vol. 12, no. 2, pp. e867–e880, 2018.
 X. Yang, J. Liu, Y. Pei, X. Zheng, and K. Tang, ‘Recent progress in preparation and application of nano‐chitin materials’, Energy & Environmental Materials, vol. 3, no. 4, pp. 492–515, 2020.
 V. Zubillaga et al., ‘Chitin nanoforms provide mechanical and topological cues to support growth of human adipose stem cells in chitosan matrices’, Biomacromolecules, vol. 19, no. 7, pp. 3000–3012, 2018.
 K. Azuma, S. Ifuku, T. Osaki, Y. Okamoto, and S. Minami, ‘Preparation and biomedical applications of chitin and chitosan nanofibers’, Journal of biomedical nanotechnology, vol. 10, no. 10, pp. 2891–2920, 2014.
Several research findings have shown that nanochitin being used in wound dressing promotes skin wound regeneration. 
ChNFs hydrogels can stimulate bone marrow stromal cells (BMSCs) to develop into angiogenic cells and fibroblasts to aid in repairing skin wounds.
Nanochitin can be added to composite materials to enhance their mechanical qualities as well as to encourage cell adhesion, growth, and proliferation 
According to reports, chitosan-nanochitin biomaterials promote the adherence and growth of stem cells. 
Anti Cancer Treatment
Nanochitin has been employed extensively in anticancer therapy in recent years. It can also cause cancer cells to undergo apoptosis. It is obviously harmful to many types of cancer cells but not poisonous to non-cancer cells. 
Chitin and its derivatives are among the most widely used polymers for several cosmetic/cosmeceuticals applications due to their excellent biological properties. Specifically, they are considered of great utility because they act both as carriers and active ingredients
 I. Aranaz et al., ‘Cosmetics and cosmeceutical applications of chitin, chitosan and their derivatives’, Polymers, vol. 10, no. 2, p. 213, 2018.
 P. Morganti and Y. H. Li, ‘Innovation in cosmetic and medical science. The role of chitin nanofibrils composites’, J. Appl. Cosmetol, vol. 33, pp. 9–24, 2015.
 P. Morganti, M. Palombo, P. Palombo, G. Fabrizi, A. Cardillo, and F. Carezzi, ‘Cosmetic science in skin aging: achieving the efficacy by the chitin nano-structured crystallites’, SÖFW-Journal, vol. 136, no. 3, 2010.
 T. A. Ahmed and B. M. Aljaeid, ‘Preparation, characterization, and potential application of chitosan, chitosan derivatives, and chitosan metal nanoparticles in pharmaceutical drug delivery’, Drug design, development and therapy, pp. 483–507, 2016.
 R. A. Muzzarelli, ‘Carboxymethylated chitins and chitosans’, Carbohydrate polymers, vol. 8, no. 1, pp. 1–21, 1988.
 L. Chen, Y. Du, H. Wu, and L. Xiao, ‘Relationship between molecular structure and moisture‐retention ability of carboxymethyl chitin and chitosan’, Journal of Applied Polymer Science, vol. 83, no. 6, pp. 1233–1241, 2002.
Anti Ageing and Repair
CNs have proven to have a repairing and anti-aging effect,on both skin and scalp . This polymer is able to penetrate into the hair scales, bind to keratin and repair its fibres in depth, improving shine. Chitin-based emulsions enriched with antioxidants and immunomodulant, have been effective in reducing wrinkles, spots and roughness, and increasing hydration and elasticity, resulting in younger-looking skin within weeks 
Transdermal Delivery of Ingredients
Chitin nanoparticles are widely used for topical and transdermal delivery of active ingredients . For example, retinol, a derivative of vitamin A, can be included in the chitin-based nanosystems for the treatment of acne or skin wrinkles 
Moisture Absorption and Retention
The carboxymethylated derivatives of chitin and chitosan (CM-chitin and CM-chitosan respectively), can promote moisture absorption and retention of the stratum corneum (the outermost layer of the epidermis) comparable to hyaluronic acid (HA), through the formation of a moisturising film on the skin [4,5]
Chitin and chitosan excel in 3D printing due to biodegradability, biocompatibility, low toxicity, and customizable properties. They offer sustainability, antimicrobial potential, and versatility for various applications, from medical implants to eco-friendly packaging.
Bone Tissue Repair
Chitosan based 3D scaffolds exhibit an enhanced effect in bone tissue repair. Chitosan biopolymers can be used solely or combined with bioactive ceramics, synthetic, and other natural polymers as printing materials for 3D-printed constructs for bone repair. 
Aydogdu et al. showed that 3D PLA/β-TCP scaffolds integrated with chitosan hydrogel synergistically increased the antimicrobial activity when loaded with amoxicillin .
Chitosan is widely utilized in micro- and nano-particle drug delivery systems due to its pH sensitivity, mucoadhesivity, and the capability to transiently open epithelial tight junctions. [3,4,5] Chitosan-based drug delivery vehicles, such as a biodegradable wound dressing for lidocaine delivery, have also been created using printing techniques, as demonstrated by Long and colleagues. 
Skin Tissue Regeneration
Chitosan 3D printing is revolutionizing skin tissue regeneration by harnessing its unique properties. Chitosan's compatibility makes it an ideal scaffold for wound healing and skin regeneration, showcasing its potential in advancing regenerative medicine. For instance, Intini et al. utilized the extrusion-based 3D printing method to craft chitosan scaffolds designed for the regeneration of skin tissue. 
 L. R. Yadav, S. V. Chandran, K. Lavanya, and N. Selvamurugan, ‘Chitosan-based 3D-printed scaffolds for bone tissue engineering’, International Journal of Biological Macromolecules, vol. 183, pp. 1925–1938, Jul. 2021, doi: 10.1016/j.ijbiomac.2021.05.215.
 M. O. Aydogdu et al., ‘Comparative characterization of the hydrogel added PLA/β-TCP scaffolds produced by 3D bioprinting’, Bioprinting, vol. 13, p. e00046, Mar. 2019, doi: 10.1016/j.bprint.2019.e00046.
 S. M. Ahsan, M. Thomas, K. K. Reddy, S. G. Sooraparaju, A. Asthana, and I. Bhatnagar, ‘Chitosan as biomaterial in drug delivery and tissue engineering’, International Journal of Biological Macromolecules, vol. 110, pp. 97–109, Apr. 2018, doi: 10.1016/j.ijbiomac.2017.08.140.
 S. A. Agnihotri, N. N. Mallikarjuna, and T. M. Aminabhavi, ‘Recent advances on chitosan-based micro- and nanoparticles in drug delivery’, Journal of Controlled Release, vol. 100, no. 1, pp. 5–28, Nov. 2004, doi: 10.1016/j.jconrel.2004.08.010.
 S. Rodrigues, M. Dionísio, C. R. López, and A. Grenha, ‘Biocompatibility of Chitosan Carriers with Application in Drug Delivery’, Journal of Functional Biomaterials, vol. 3, no. 3, Art. no. 3, Sep. 2012, doi: 10.3390/jfb3030615.
 J. Long, A. E. Etxeberria, A. V. Nand, C. R. Bunt, S. Ray, and A. Seyfoddin, ‘A 3D printed chitosan-pectin hydrogel wound dressing for lidocaine hydrochloride delivery’, Materials Science and Engineering: C, vol. 104, p. 109873, Nov. 2019, doi: 10.1016/j.msec.2019.109873.
 C. Intini et al., ‘3D-printed chitosan-based scaffolds: An in vitro study of human skin cell growth and an in-vivo wound healing evaluation in experimental diabetes in rats’, Carbohydrate Polymers, vol. 199, pp. 593–602, Nov. 2018, doi: 10.1016/j.carbpol.2018.07.057.