Chitosan (CS) is a hemi-synthetic cationic linear polysaccharide produced by the deacetylation of chitin. CS is non-toxic, highly biocompatible, and biodegradable, and it has a low immunogenicity. Additionally, CS has inherent antibacterial properties and a mucoadhesive character and can disrupt epithelial tight junctions, thus acting as a permeability enhancer. As such, CS and its derivatives are well-suited for the challenging field of ocular drug delivery. In the present review article, we will discuss the properties of CS that contribute to its successful application in ocular delivery before reviewing the latest advances in the use of CS for the development of novel ophthalmic delivery systems. Colloidal nanocarriers (nanoparticles, micelles, liposomes) will be presented, followed by CS gels and lenses and ocular inserts. Finally, instances of CS coatings, aiming at conferring mucoadhesiveness to other matrixes, will be presented.

3D printing, or additive manufacturing, has gained considerable interest due to its versatility regarding design as well as in the large choice of materials. It is a powerful tool in the field of personalized pharmaceutical treatment, particularly crucial for pediatric and geriatric patients. Polysaccharides are abundant and inexpensive natural polymers, that are already widely used in the food industry and as excipients in pharmaceutical and cosmetic formulations. Due to their intrinsic properties, such as biocompatibility, biodegradability, non-immunogenicity, etc., polysaccharides are largely investigated as matrices for drug delivery. Although an increasing number of interesting reviews on additive manufacturing and drug delivery are being published, there is a gap concerning the printing of polysaccharides. In this article, we will review recent advances in the 3D printing of polysaccharides focused on drug delivery applications. Among the large family of polysaccharides, the present review will particularly focus on cellulose and cellulose derivatives, chitosan and sodium alginate, printed by fused deposition modeling and extrusion-based printing.

The aim of this work was to evaluate the effectiveness of neat chitosan (CS) and its derivatives with 2-acrylamido-2-methyl-1-propanesulfonic acid (AAMPS) and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSP) as appropriate nanocarriers for the simultaneous ocular administration of dexamethasone sodium phosphate (DxP) and chloramphenicol (CHL). The derivatives CS-AAMPS and CS-MEDSP have been synthesized by free-radical polymerization and their structure has been proved by Fourier-Transformed Infrared Spectroscopy (FT-IR) spectroscopy. Both derivatives exhibited low cytotoxicity, enhanced mucoadhesive properties and antimicrobial activity against Staphylococcus aureus (S.aureus) and Escherichia coli (E. coli). Encapsulation was performed via ionic crosslinking gelation using sodium tripolyphosphate (TPP) as the crosslinking agent. Dynamic light scattering measurements (DLS) showed that the prepared nanoparticles had bimodal distribution and sizes ranging from 50–200 nm and 300–800 nm. Drugs were encapsulated in their crystalline (CHL) or amorphous (DexSP) form inside nanoparticles and their release rate was dependent on the used polymer. The CHL dissolution rate was substantially enhanced compared to the neat drug and the release time was extended up to 7 days. The release rate of DexSP was much faster than that of CHL and was prolonged up to 3 days. Drug release modeling unveiled that diffusion is the main release mechanism for both drugs. Both prepared derivatives and their drug-loaded nanoparticles could be used for extended and simultaneous ocular release formulations of DexSP and CHL drugs.

Chitosan (CS) is a polymer extensively used in drug delivery formulations mainly due to its biocompatibility and low toxicity. In the present study, chitosan was used for nanoencapsulation of a budesonide (BUD) drug via the well-established ionic gelation technique and a slight modification of it, using also poly(vinyl alcohol) (PVA) as a surfactant. Scanning electron microscopy (SEM) micrographs revealed that spherical nanoparticles were successfully prepared with average sizes range between 363 and 543 nm, as were measured by dynamic light scattering (DLS), while zeta potential verified their positive charged surface. X-ray diffraction (XRD) patterns revealed that BUD was encapsulated in crystalline state in nanoparticles but with a lower degree of crystallinity than the neat drug, which was also proven by differential scanning calorimetry (DSC) and melting peak measurements. This could be attributed to interactions that take place between BUD and CS, which were revealed by FTIR and by an extended computational study. An in vitro release study of budesonide showed a slight enhancement in the BUD dissolution profile, compared to the neat drug. However, drug release was substantially increased by introducing PVA during the nanoencapsulation procedure, which is attributed to the higher amorphization of BUD on these nanoparticles. The release curves were analyzed using a diffusion model that allows estimation of BUD diffusivity in the nanoparticles.

In the present study, chitosan (CS) and pectin (PEC) were utilized for the preparation of 3D printable inks through pneumatic extrusion for biomedical applications. CS is a polysaccharide with beneficial properties; however, its printing behavior is not satisfying, rendering the addition of a thickening agent necessary, i.e., PEC. The influence of PEC in the prepared inks was assessed through rheological measurements, altering the viscosity of the inks to be suitable for 3D printing. 3D printing conditions were optimized and the effect of different drying procedures, along with the presence or absence of a gelating agent on the CS-PEC printed scaffolds were assessed. The mean pore size along with the average filament diameter were measured through SEM micrographs. Interactions among the characteristic groups of the two polymers were evident through FTIR spectra. Swelling and hydrolysis measurements confirmed the influence of gelation and drying procedure on the subsequent behavior of the scaffolds. Ascribed to the beneficial pore size and swelling behavior, fibroblasts were able to survive upon exposure to the ungelated scaffolds.