Chitosan: A Potential Biopolymer in Drug Delivery and Biomedical Applications

Injectable Lyophilized Chitosan-Thrombin-Platelet-Rich Plasma (CS-FIIa-PRP) Implant to Promote Tissue Regeneration: In Vitro and Ex Vivo Solidification Properties

Freeze-dried chitosan formulations solubilized in platelet-rich plasma (PRP) are currently evaluated as injectable implants with the potential for augmenting the standard of care for tissue repair in different orthopedic conditions. The present study aimed to shorten the solidification time of such implants, leading to an easier application and a facilitated solidification in a wet environment, which were direct demands from orthopedic surgeons. The addition of thrombin to the formulation before lyophilization was explored. The challenge was to find a formulation that coagulated fast enough to be applied in a wet environment but not too fast, which would make handling/injection difficult. Four thrombin concentrations were analyzed (0.0, 0.25, 0.5, and 1.0 NIH/mL) in vitro (using thromboelastography, rheology, indentation, syringe injectability, and thrombin activity tests) as well as ex vivo (by assessing the implant's adherence to tendon tissue in a wet environment). The biomaterial containing 0.5 NIH/mL of thrombin significantly increased the coagulation speed while being easy to handle up to 6 min after solubilization. Furthermore, the adherence of the biomaterial to tendon tissues was impacted by the biomaterial-tendon contact duration and increased faster when thrombin was present. These results suggest that our biomaterial has great potential for use in regenerative medicine applications.

Chitosan-Based Nanoparticles for Nucleic Acid Delivery: Technological Aspects, Applications, and Future Perspectives

Chitosan is a naturally occurring polymer derived from the deacetylation of chitin, which is an abundant carbohydrate found mainly in the shells of various marine and terrestrial (micro)organisms. Chitosan has been extensively used to construct nanoparticles (NPs), which are biocompatible, biodegradable, non-toxic, easy to prepare, and can function as effective drug delivery systems. Moreover, chitosan NPs have been employed in gene and vaccine delivery, as well as advanced cancer therapy, and they can also serve as new therapeutic tools against viral infections. In this review, we summarize the most recent developments in the field of chitosan-based NPs intended as nucleic acid delivery vehicles and gene therapy vectors. Special attention is given to the technological aspects of chitosan complexes for nucleic acid delivery.

Caffeic Acid-Zinc Basic Salt/Chitosan Nanohybrid Possesses Controlled Release Properties and Exhibits In Vivo Anti-Inflammatory Activities

Caffeic acid (CA) exhibits a myriad of biological activities including cardioprotective action, antioxidant, antitumor, anti-inflammatory, and antimicrobial properties. On the other hand, CA presents low water solubility and poor bioavailability, which have limited its use for therapeutic applications. The objective of this study was to develop a nanohybrid of zinc basic salts (ZBS) and chitosan (Ch) containing CA (ZBS-CA/Ch) and evaluate its anti-edematogenic and antioxidant activity in dextran and carrageenan-induced paw edema model. The samples were obtained by coprecipitation method and characterized by X-ray diffraction, Fourier transform infrared (FT-IR), scanning electron microscope (SEM) and UV-visible spectroscopy. The release of caffeate anions from ZBS-CA and ZBS-CA/Ch is pH-dependent and is explained by a pseudo-second order kinetics model, with a linear correlation coefficient of R² ≥ 0.99 at pH 4.8 and 7.4. The in vivo pharmacological assays showed excellent anti-edematogenic and antioxidant action of the ZBS-CA/Ch nanoparticle with slowly releases of caffeate anions in the tissue, leading to a prolongation of CA-induced anti-edematogenic and anti-inflammatory activities, as well as improving its inhibition or sequestration antioxidant action toward reactive species. Overall, this study highlighted the importance of ZBS-CA/Ch as an optimal drug carrier.

Positively Charged-Amylose-Entangled Au-Nanoparticles Acting as Protein Carriers and Potential Adjuvants to SARS-CoV-2 Subunit Vaccines

The COVID-19 pandemic continues to spread worldwide. To protect and control the spread of SARS-CoV-2, varieties of subunit vaccines based on spike (S) proteins have been approved for human applications. Here, we report a new subunit vaccine design strategy that functions as both an antigen carrier and an adjuvant in immunization to elicit high-level immune responses. The complex of 2-hydroxypropyl-trimethylammonium chloride chitosan and amylose entangles Au nanoparticles (HTCC/amylose/AuNPs) forming 40 nm nanocarriers with a positive charge. The obtained positively charged nanoparticles reveal many merits, including the larger S protein loading capacity in PBS buffer, higher cellular uptake ability, and lower cell cytotoxicity, supporting their potential as safe vaccine nanocarriers. Two functionalized nanoparticle subunit vaccines are prepared via loading full-length S proteins derived from SARS-CoV-2 variants. In mice, both prepared vaccines elicit high specific IgG antibodies, neutralize antibodies, and immunoglobulin IgG1 and IgG2a. The prepared vaccines also elicit robust T- and B-cell immune responses and increase CD19⁺ B cells, CD11C⁺ dendritic cells, and CD11B⁺ macrophages at the alveoli and bronchi of the immunized mice. Furthermore, the results of skin safety tests and histological observation of organs indicated in vivo safety of HTCC/amylose/AuNP-based vaccines. Summarily, our prepared HTCC/amylose/AuNP have significant potential as general vaccine carriers for the delivery of different antigens with potent immune stimulation.

"Bioinspired" Membrane-Coated Nanosystems in Cancer Theranostics: A Comprehensive Review

Achieving precise cancer theranostics necessitates the rational design of smart nanosystems that ensure high biological safety and minimize non-specific interactions with normal tissues. In this regard, "bioinspired" membrane-coated nanosystems have emerged as a promising approach, providing a versatile platform for the development of next-generation smart nanosystems. This review article presents an in-depth investigation into the potential of these nanosystems for targeted cancer theranostics, encompassing key aspects such as cell membrane sources, isolation techniques, nanoparticle core selection, approaches for coating nanoparticle cores with the cell membrane, and characterization methods. Moreover, this review underscores strategies employed to enhance the multi-functionality of these nanosystems, including lipid insertion, membrane hybridization, metabolic engineering, and genetic modification. Additionally, the applications of these bioinspired nanosystems in cancer diagnosis and therapeutics are discussed, along with the recent advances in this field. Through a comprehensive exploration of membrane-coated nanosystems, this review provides valuable insights into their potential for precise cancer theranostics.

Chitosan Hydrogel-Delivered ABE8e Corrects PAX9 Mutant in Dental Pulp Stem Cells

Hypodontia (dental agenesis) is a genetic disorder, and it has been identified that the mutation C175T in PAX9 could lead to hypodontia. Cas9 nickase (nCas9)-mediated homology-directed repair (HDR) and base editing were used for the correction of this mutated point. This study aimed to investigate the effect of HDR and the base editor ABE8e in editing PAX9 mutant. It was found that the chitosan hydrogel was efficient in delivering naked DNA into dental pulp stem cells (DPSCs). To explore the influence of the C175T mutation in PAX9 on the proliferation of DPSCs, hydrogel was employed to deliver PAX9 mutant vector into DPSCs, finding that the PAX9-containing C175T mutation failed to promote the proliferation of DPSCs. Firstly, DPSCs stably carrying PAX9 mutant were constructed. Either an HDR or ABE8e system was delivered into the above-mentioned stable DPSCs, and then the correction efficiency using Sanger sequencing and Western blotting was determined. Meanwhile, the ABE8e presented significantly higher efficiency in correcting C175T compared with HDR. Furthermore, the corrected PAX9 presented enhanced viability and differentiation capacity for osteogenic and neurogenic lineages; the corrected PAX9 even possessed extremely enhanced transcriptional activation ability. In summary, this study has powerful implications for studies into base editors, chitosan hydrogel, and DPSCs in treating hypodontia.