**5. Alginate nanoparticles**

Nanoaggregates, nano-capsules, and nanospheres are nanoscale systems (10–1000 nm) that can contain enzymes, medicines, and other compounds by dissolving, encasing, or adding them to the matrix of the particle. Different methods used for prepare nanoparticles involves: (a) nanoaggregates, which are nanoscale colloidal structures in which the drug is mechanically distributed and can take on a variety of morphologies; (b) nano-capsules, which are vesicular systems in which the drug is confined to an oily or aqueous liquid centre enclosed by a polymeric membrane, (c) nanospheres, which are spherical particles with a gelled interior in which the entrapped component is physically distributed, or (d) nano-capsules with a structured interior, which are a hybrid of a nano-capsule and a nanosphere; they are made by first preparing a nanosphere and then forming an additional

#### *Curcumin-Alginate Mixed Nanocomposite: An Evolving Therapy for Wound Healing DOI: http://dx.doi.org/10.5772/intechopen.98830*

shell on the nanosphere's interface [51–55]. As previously mentioned, there are two methods for producing alginate nanoparticles: (i) complexation, which occurs in an aqueous solution to form alginate nano-aggregates or on the interface of an oil droplet to form alginate nano-capsules; a crosslinker (e.g., calcium from calcium chloride) is used for complexation of alginate, and complexation may also occur by mixing alginate with an oppositely charged polyelectrolyte (*e.g*., poly-L-lysine); and (ii) alginate in-oil emulsification, followed by external or internal alginate emulsion droplet gelation, resulting in alginate nanospheres [56]. We can summarise the methods used in synthesising alginate-based nanomaterials as-controlled jellification using Ca2+ ions, formation of polyionic complexes through ionotropic gelation via intermolecular interactions, spray drying followed by crosslinking, alginate nanoaggregates through self-assembly, fabrication of nanocomposite fibrous scaffolds and nanoparticles respectively by electrospinning and electro-spraying, fabrication of nanocomposite fibrous scaffolds by thermally-induced phase separation and formation of alginate nanoparticle using a microfluidics- aided polyelectrolyte Complexation [57].
