Glycol Chitosan: A Water-Soluble Polymer for Cell Imaging and Drug Delivery

Advances in the delivery of anticancer drugs by nanoparticles and chitosan-based nanoparticles

Cancer is the leading cause of death globally, and conventional treatments have limited efficacy with severe side effects. The use of nanotechnology has the potential to reduce the side effects of drugs by creating efficient and controlled anticancer drug delivery systems. Nanoparticles (NPs) used as drug carriers offer several advantages, including enhanced drug protection, biodistribution, selectivity and, pharmacokinetics. Therefore, this review is devoted to various organic (lipid, polymeric) as well as inorganic nanoparticles based on different building units and providing a wide range of potent anticancer drug delivery systems. Within these nanoparticulate systems, chitosan (CS)-based NPs are discussed with particular emphasis due to the unique properties of CS and its derivatives including non-toxicity, biodegradability, mucoadhesivity, and tunable physico-chemical as well as biological properties allowing their alteration to specifically target cancer cells. In the context of streamlining the nanoparticulate drug delivery systems (DDS), innovative nanoplatform-based cancer therapy pathways involving passive and active targeting as well as stimuli-responsive DDS enhancing overall orthogonality of developed NP-DDS towards the target are included. The most up-to-date information on delivering anti-cancer drugs using modern dosage forms based on various nanoparticulate systems and, specifically, CSNPs, are summarised and evaluated concerning their benefits, limitations, and advanced applications.

Highly efficient dip catalysts using bacterial cellulose impregnated with self-crosslinked glycol chitosan and silver nanoparticles for 4-nitrophenol reduction

The application of environmentally friendly and sustainable catalysts requires efficient and safe preparation methods using cheap and renewable materials. Although many metal nanoparticles (NPs) have low colloidal stability, they are still very effective as catalysts. Using a straightforward method, we developed a bacterial cellulose-glycol chitosan-silver (BC-GCS-Ag) nanocomposite, by introducing both AgNPs and self-crosslinked GCS within the BC network. Self-crosslinking of GCS occurred during the formation of AgNPs by employing the glycol moieties for reduction to produce aldehyde functionalities, thereby forming Schiff's base bonds within the GCS structure. Using GCS, well-defined AgNPs within the BC matrix. The formation of AgNPs and the self-crosslinking of GCS were characterized using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that spherical AgNPs with a mean diameter of 10 nm exhibited a well-organized structure within the BC-GCS matrix. The BC-GCS-Ag nanocomposite was applied as dip catalyst for the reduction of 4-nitrophenol (4NP) to 4-aminophenol (4AP), chosen as a model reaction. The results showed that the catalytic reaction was completed within 4 min, with high reusability (10 times) and without loss of catalyst. The reaction followed pseudo-first-order kinetics with a high rate constant of 0.582 min-1. Therefore, the BC-GCS-Ag dip catalyst is an attractive alternative for environmentally friendly and sustainable catalysis, owing to its exceptional catalytic performance, high recyclability, and stability, as well as the minimal environmental footprint of the supporting materials.

Docetaxel-tethered di-Carboxylic Acid Derivatised Fullerenes: A Promising Drug Delivery Approach for Breast Cancer

Docetaxel (DTX) has become widely accepted as a first-line treatment for metastatic breast cancer; however, the frequent development of resistance provides challenges in treating the disease.C60 fullerene introduces a unique molecular form of carbon, exhibiting attractive chemical and physical properties. Our study aimed to develop dicarboxylic acid-derivatized C60 fullerenes as a novel DTX delivery carrier. This study investigated the potential of water-soluble fullerenes to deliver the anti-cancer drug DTX through a hydrophilic linker. The synthesis was carried out using the Prato reaction. The spectroscopic analysis confirmed the successful conjugation of DTX molecules over fullerenes. The particle size of nanoconjugate was reported to be 122.13 ± 1.63 nm with a conjugation efficiency of 76.7 ± 0.14%. The designed conjugate offers pH-dependent release with significantly less plasma pH, ensuring maximum release at the target site. In-vitro cell viability studies demonstrated the enhanced cytotoxic nature of the developed nanoconjugate compared to DTX. These synthesized nanoscaffolds were highly compatible with erythrocytes, indicating the safer intravenous route administration. Pharmacokinetic studies confirmed the higher bioavailability (~ 6 times) and decreased drug clearance from the system vis-à-vis plain drug. The histological studies reveal that nanoconjugate-treated tumour cells exhibit similar morphology to normal cells. Therefore, it was concluded that this developed formulation would be a valuable option for clinical use.

Optimization of Interfacial Properties Improved the Stability and Activity of the Catalase Enzyme Immobilized on Plastic Nanobeads

The immobilization of catalase (CAT), a crucial oxidoreductase enzyme involved in quenching reactive oxygen species, on colloids and nanoparticles presents a promising strategy to improve dispersion and storage stability while maintaining its activity. Here, the immobilization of CAT onto polymeric nanoparticles (positively (AL) or negatively (SL) charged) was implemented directly (AL) or via surface functionalization (SL) with water-soluble chitosan derivatives (glycol chitosan (GC) and methyl glycol chitosan (MGC)). The interfacial properties were optimized to obtain highly stable AL-CAT, SL-GC-CAT, and SL-MGC-CAT dispersions, and confocal microscopy confirmed the presence of CAT in the composites. Assessment of hydrogen peroxide decomposition ability revealed that applying chitosan derivatives in the immobilization process not only enhanced colloidal stability but also augmented the activity and reusability of CAT. In particular, the use of MGC has led to significant advances, indicating its potential for industrial and biomedical applications. Overall, the findings highlight the advantages of using chitosan derivatives in CAT immobilization processes to maintain the stability and activity of the enzyme as well as provide important data for the development of processable enzyme-based nanoparticle systems to combat reactive oxygen species.

Chitosan: An overview of biological activities, derivatives, properties, and current advancements in biomedical applications

The second and most often utilized natural polymer is chitosan (CS), a naturally existing amino polysaccharide that is produced by deacetylating chitin. Numerous applications have been the subject of in-depth investigation due to its non-hazardous, biologically compatible, and biodegradable qualities. Chitosan's characteristics, such as mucoadhesion, improved permeability, controlled release of drugs, in situ gelation process, and antibacterial activity, depend on its amino (-NH2) and hydroxyl groups (-OH). This study examines the latest findings in chitosan research, including its characteristics, derivatives, preliminary research, toxic effects, pharmaceutical kinetics and chitosan nanoparticles (CS-NPs) based for non-parenteral delivery of drugs. Chitosan and its derivatives have a wide range of physical and chemical properties that make them highly promising for use in the medicinal and pharmaceutical industries. The characteristics and biological activities of chitosan and its derivative-based nanomaterials for the delivery of drugs, therapeutic gene transfer, delivery of vaccine, engineering tissues, evaluations, and other applications in medicine are highlighted in detail in the current review. Together with the techniques for binding medications to nanoparticles, the application of the nanoparticles was also dictated by their physical properties that were classified and specified. The most recent research investigations on delivery of drugs chitosan nanoparticle-based medication delivery methods applied topically, through the skin, and through the eyes were considered.

A Study on the Dilational Modulus Measurement of Polyacrylic Acid Films at Air-Water Interface by Pendant Bubble Tensiometry

The dilational modulus (E) of polymer films has been commonly measured using the oscillating ring/bubble/drop methods with an external force, and often without specifying the state of the adsorbed film. This study explores an approach where E was determined from the relaxations of surface tension (ST) and surface area (SA) of natural perturbations, in which ST and SA were monitored using a pendant bubble tensiometer. The E of the adsorbed film of PAA (polyacrylic acid) was evaluated for aqueous solutions at CPAA = 5 × 10-4 g/cm3, [MW = 5, 25, and 250 (kDa)]. The E (=dγ/dlnA) was estimated from the surface dilational rate (dlnA/dt) and the rate of ST change (dγ/dt) of the bubble surface from the natural perturbation caused by minute variations in ambient temperature. The data revealed that (i) a considerable time is required to reach the equilibrium-ST (γeq) and to attain the saturated dilational modulus (Esat) of the adsorbed PAA film, (ii) both γeq and Esat of PAA solutions increase with MW of PAA, (iii) a lower MW solution requires a longer time to reach its γeq and Esat, and (iv) this approach is workable for evaluating the E of adsorbed polymer films.

Tuning light-driven oxidation of styrene inside water-soluble nanocages

Selective functionalization of innate sp2 C-H bonds under ambient conditions is a grand synthetic challenge in organic chemistry. Here we combine host-guest charge transfer-based photoredox chemistry with supramolecular nano-confinement to achieve selective carbonylation of styrene by tuning the dioxygen concentration. We observe exclusive photocatalytic formation of benzaldehyde under excess O2 (>1 atm) while Markovnikov addition of water produced acetophenone in deoxygenated condition upon photoexcitation of confined styrene molecules inside a water-soluble cationic nanocage. Further by careful tuning of the nanocage size, electronics, and guest preorganization, we demonstrate rate enhancement of benzaldehyde formation and a complete switchover to the anti-Markovnikov product, 2-phenylethan-1-ol, in the absence of O2. Raman spectroscopy, 2D 1H-1H NMR correlation experiments, and transient absorption spectroscopy establish that the site-selective control on the confined photoredox chemistry originates from an optimal preorganization of styrene molecules inside the cavity. We envision that the demonstrated host-guest charge transfer photoredox paradigm in combination with green atom-transfer reagents will enable a broad range of sp2 carbon-site functionalization.

A glycol chitosan derivative with extrafibrillar demineralization potential for self-etch dentin bonding

OBJECTIVES

Extrafibrillar demineralization is an etching technique that removes only minerals from around the collagen fibrils for resin infiltration. The intrafibrillar minerals are left intact to avoid their replacement by water that is hard for adhesive resin monomers to displace. The present work reported the synthesis of a water-soluble methacryloyloxy glycol chitosan-EDTA conjugate (GCE-MA) and evaluated its potential as an extrafibrillar demineralization agent for self-etch dentin bonding.

METHODS

Glycol chitosan-EDTA was functionalized with a methacryloyloxy functionality. Conjugation was confirmed using Fourier transform-infrared spectroscopy. The GCE-MA was used to prepare experimental self-etch primers. Extrafibrillar demineralization of the primers was evaluated with scaning electron microscopy and transmission electron microscopy. The feasibility of this new self-etch bonding approach was evaluated using microtensile bond strength testing and inhibition of dentin gelatinolytic activity. The antibacterial activity and cytotoxicity of GCE-MA were also analyzed.

RESULTS

Conjugation of EDTA and the methacryloyloxy functionality to glycol chitosan was successful. The functionalized conjugate was capable of extrafibrillar demineralization of mineralized collagen fibrils. Tensile bond strength of the experimental self-etch primer to dentin was comparable to that of phosphoric acid-etched dentin and the commercial self-etch primer Clearfil SE Bond 2. The GCE-MA also inhibited soluble rhMMP-9. In-situ zymography detected minimal fluorescence in hybrid layers conditioned with the experimental primer. The GCE-MA was noncytotoxic and possessed antibacterial activities against planktonic bacteria.

SIGNIFICANCE

Synthesis of GCE-MA brought into fruition a self-etch conditioner that selectively demineralizes the extrafibrillar mineral component of dentin. A self-etch primer prepared with GCE-MA achieved bond strengths comparable to commercial reference adhesive systems.

Oral Insulin Delivery: A Review on Recent Advancements and Novel Strategies

BACKGROUND

Due to the lifestyle of people in the community in recent years, the prevalence of diabetes mellitus has increased, so New drugs and related treatments are also being developed.

INTRODUCTION

One of the essential treatments for diabetes today is injectable insulin forms, which have their problems and limitations, such as invasive and less admission of patients and high cost of production. According to the mentioned issues, Theoretically, Oral insulin forms can solve many problems of injectable forms.

METHODS

Many efforts have been made to design and introduce Oral delivery systems of insulin, such as lipid-based, synthetic polymer-based, and polysaccharide-based nano/microparticle formulations. The present study reviewed these novel formulations and strategies in the past five years and checked their properties and results.

RESULTS

According to peer-reviewed research, insulin-transporting particles may preserve insulin in the acidic and enzymatic medium and decrease peptide degradation; in fact, they could deliver appropriate insulin levels to the intestinal environment and then to blood. Some of the studied systems increase the permeability of insulin to the absorption membrane in cellular models. In most investigations, in vivo results revealed a lower ability of formulations to reduce BGL than subcutaneous form, despite promising results in in vitro and stability testing.

CONCLUSION

Although taking insulin orally currently seems unfeasible, future systems may be able to overcome mentioned obstacles, making oral insulin delivery feasible and producing acceptable bioavailability and treatment effects in comparison to injection forms.

A Biomimicking and Multiarm Self-Indicating Nanoassembly for Site-Specific Photothermal-Potentiated Thrombolysis Assessed in Microfluidic and In Vivo Models

Thrombolytic and antithrombotic therapies are limited by short circulation time and the risk of off-target hemorrhage. Integrating a thrombus-homing strategy with photothermal therapy are proposed to address these limitations. Using glycol chitosan, polypyrrole, iron oxide and heparin, biomimicking GCPIH nanoparticles are developed for targeted thrombus delivery and thrombolysis. The nanoassembly achieves precise delivery of polypyrrole, exhibiting biocompatibility, selective accumulation at multiple thrombus sites, and enhanced thrombolysis through photothermal activation. To simulate targeted thrombolysis, a microfluidic model predicting thrombolysis dynamics in realistic pathological scenarios is designed. Human blood assessments validate the precise homing of GCPIH nanoparticles to activated thrombus microenvironments. Efficient near-infrared phototherapeutic effects are demonstrated at thrombus lesions under physiological flow conditions ex vivo. The combined investigations provide compelling evidence supporting the potential of GCPIH nanoparticles for effective thrombus therapy. The microfluidic model also offers a platform for advanced thrombolytic nanomedicine development.

Chitosan and its derivatives in 3D/4D (bio) printing for tissue engineering and drug delivery applications

Tissue engineering research has undergone to a revolutionary improvement, thanks to technological advancements, such as the introduction of bioprinting technologies. The ability to develop suitable customized biomaterial inks/bioinks, with excellent printability and ability to promote cell proliferation and function, has a deep impact on such improvements. In this context, printing inks based on chitosan and its derivatives have been instrumental. Thus, the current review aims at providing a comprehensive overview on chitosan-based materials as suitable inks for 3D/4D (bio)printing and their applicability in creating advanced drug delivery platforms and tissue engineered constructs. Furthermore, relevant strategies to improve the mechanical and biological performances of this biomaterial are also highlighted.

Polysaccharide-Based Supramolecular Hydrogel Coatings with Corrosion Barrier Zone for Protection of Patina Bronze

Protective coatings for bronze relics should adhere to the basic principles of cultural relic preservation, such as not altering the color and appearance of the artifacts, and being moderately combined with the artifacts to resist erosion due to external environments (such as water and gas). This paper presents the development of a physically crosslinked supramolecular hydrogel produced from guanidinium-based chitosan (GC). The hydrogel exhibits the excellent adsorption protection of bronze, and the addition of clay enhances the water barrier properties of the chitosan film. The supramolecular interaction between sodium polyacrylate/GC/clay confers corrosion buffering capability to the hydrogel coating in corrosive environments, and the gel coating can be self-healing at room temperature for 24 h. The fabricated nanocomposites were comprehensively characterized using various methods (Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, etc.). The electrochemical properties of coated specimens were evaluated, and the impedance spectrum revealed a large impedance arc indicating high charge resistance, which has a corrosion resistance effect.

Biocompatible Glycol Chitosan Microgels as Effective Drug Carriers

Glycol chitosan (GC) is a chitosan (CH) derivative with improved water solubility with regards to CH which affords significant solubility advantages. In this study, microgels of GC as p(GC) were synthesized by a microemulsion technique at various crosslinking ratios e.g., 5%, 10%, 50%, 75%, and 150% based on the repeating unit of GC using divinyl sulfone (DVS) as a crosslinker. The prepared p(GC) microgels were tested for blood compatibility and it was found that p(GC) microgels at 1.0 mg/mL concentration possessed a 1.15 ± 0.1% hemolysis ratio and 89 ± 5% blood clotting index value confirming their hemocompatibility. In addition, p(GC) microgels were found biocompatible with 75.5 ± 5% cell viability against L929 fibroblasts even at a 2.0 mg/mL concentration. By loading and releasing tannic acid (TA) (a polyphenolic compound with high antioxidant activity) as an active agent, p(GC) microgels' possible drug delivery device application was examined. The TA loading amount of p(GC) microgels was determined as 323.89 mg/g, and TA releases from TA loaded microgels (TA@p(GC)) were found to be linear within 9 h and a total amount of TA released was determined as 42.56 ± 2 mg/g within 57 h. According to the Trolox equivalent antioxidant capacity (TEAC) test, 400 µL of the sample added to the ABTS+ solution inhibited 68.5 ± 1.7% of the radicals. On the other hand, the total phenol content (FC) test revealed that 2000 μg/mL of TA@p(GC) microgels resulted in 27.5 ± 9.5 mg/mL GA eq antioxidant properties.

The Role of Mucoadhesion and Mucopenetration in the Immune Response Induced by Polymer-Based Mucosal Adjuvants

Mucus is a viscoelastic gel that acts as a protective barrier for epithelial surfaces. The mucosal vehicles and adjuvants need to pass through the mucus layer to make drugs and vaccine delivery by mucosal routes possible. The mucoadhesion of polymer particle adjuvants significantly increases the contact time between vaccine formulations and the mucosa; then, the particles can penetrate the mucus layer and epithelium to reach mucosa-associated lymphoid tissues. This review presents the key findings that have aided in understanding mucoadhesion and mucopenetration while exploring the influence of physicochemical characteristics on mucus-polymer interactions. We describe polymer-based particles designed with mucoadhesive or mucopenetrating properties and discuss the impact of mucoadhesive polymers on local and systemic immune responses after mucosal immunization. In future research, more attention paid to the design and development of mucosal adjuvants could lead to more effective vaccines.

Platinum(IV)-Loaded Degraded Glycol Chitosan as Efficient Platinum(IV) Drug Delivery Platform

A new class of anticancer prodrugs was designed by combining the cytotoxicity of platinum(IV) complexes and the drug carrier properties of glycol chitosan polymers: Unsymmetrically carboxylated platinum(IV) analogues of cisplatin, carboplatin and oxaliplatin, namely (OC-6-44)-acetatodiammine(3-carboxypropanoato)dichloridoplatinum(IV), (OC-6-44)-acetaodiammine(3-carboxypropanoato)(cyclobutane-1,1-dicarboxylato)platinum(IV) and (OC-6-44)-acetato(3-carboxypropanoato)(1R,2R-cyclohexane-1,2-diamine)oxalatoplatinum(IV) were synthesised and conjugated via amide bonding to degraded glycol chitosan (dGC) polymers with different chain lengths (5, 10, 18 kDa). The 15 conjugates were investigated with ¹H and ¹⁹⁵Pt NMR spectroscopy, and average amounts of platinum(IV) units per dGC polymer molecule with ICP-MS, revealing a range of 1.3-22.8 platinum(IV) units per dGC molecule. Cytotoxicity was tested with MTT assays in the cancer cell lines A549, CH1/PA-1, SW480 (human) and 4T1 (murine). IC₅₀ values in the low micromolar to nanomolar range were obtained, and higher antiproliferative activity (up to 72 times) was detected with dGC-platinum(IV) conjugates in comparison to platinum(IV) counterparts. The highest cytotoxicity (IC₅₀ of 0.036 ± 0.005 µM) was determined in CH1/PA-1 ovarian teratocarcinoma cells with a cisplatin(IV)-dGC conjugate, which is hence 33 times more potent than the corresponding platinum(IV) complex and twice more potent than cisplatin. Biodistribution studies of an oxaliplatin(IV)-dGC conjugate in non-tumour-bearing Balb/C mice showed an increased accumulation in the lung compared to the unloaded oxaliplatin(IV) analogue, arguing for further activity studies.

Applications of chitosan-based biomaterials: From preparation to spinal cord injury neuroprosthetic treatment

Spinal cord injury (SCI)-related disabilities are a serious problem in the modern society. Further, the treatment of SCI is highly challenging and is urgently required in clinical practice. Research on nerve tissue engineering is an emerging approach for improving the treatment outcomes of SCI. Chitosan (CS) is a cationic polysaccharide derived from natural biomaterials. Chitosan has been found to exhibit excellent biological properties, such as nontoxicity, biocompatibility, biodegradation, and antibacterial activity. Recently, chitosan-based biomaterials have attracted significant attention for SCI repair in nerve tissue engineering applications. These studies revealed that chitosan-based biomaterials have various functions and mechanisms to promote SCI repair, such as promoting neural cell growth, guiding nerve tissue regeneration, delivering nerve growth factors, and as a vector for gene therapy. Chitosan-based biomaterials have proven to have excellent potential for the treatment of SCI. This review aims to introduce the recent advances in chitosan-based biomaterials for SCI treatment and to highlight the prospects for further application.

Emerging evidence on the effects of plant-derived microRNAs in colorectal cancer: a review

Food nutrition and human health are still interesting international issues. Early detection, risk assessment and diet are vital to mitigate the load of intestinal diseases and enhance the quality of life. Plant-derived microRNAs could be transferred to mammalian organisms by cross-kingdom regulation which adjusts relevant target genes for their participation in the process of carcinogenesis. But the mechanism of plant-derived microRNAs in colorectal cancer is still unclear. This review aims to summarize the current pathways of plant-derived microRNAs in colorectal cancer including intestinal bacteria, the tumor microenvironment, plant active substances and protein, discuss the direct or indirect effects of plant-derived microRNAs on the occurrence and/or progression of colorectal cancer and explain why plant-derived microRNAs can be used as a potential anti-cancer agent. Moreover, the drawbacks of plant-derived microRNAs are also discussed in terms of both edible plants and synthetic delivery vectors for RNAi interference technology for human disease treatment. This review will provide a potential way for plant-derived microRNAs to target colorectal cancer.

Progress in oral insulin delivery by PLGA nanoparticles for the management of diabetes

Currently, the only practical way to treat type 1 and advanced insulin-dependent type 2 diabetes mellitus (T1/2DM) is the frequent subcutaneous injection of insulin, which is significantly different physiologically from endogenous insulin secretion from pancreatic islets and can lead to hyperinsulinemia, pain, and infection in patients with poor compliance. Hence, oral insulin delivery has been actively pursued to revolutionize the treatment of insulin-dependent diabetes. In this review, we provide an overview of recent progress in developing poly(lactic co-glycolic acid) (PLGA) nanoparticles (NPs) for oral insulin delivery. Different strategies for insulin-loaded PLGA NPs to achieve normoglycemic effects are discussed. Finally, challenges and future perspectives of PLGA NPs for oral insulin delivery are put forward.

Tumor microenvironment penetrating chitosan nanoparticles for elimination of cancer relapse and minimal residual disease

Chitosan and its derivatives are among biomaterials with numerous medical applications, especially in cancer. Chitosan is amenable to forming innumerable shapes such as micelles, niosomes, hydrogels, nanoparticles, and scaffolds, among others. Chitosan derivatives can also bring unprecedented potential to cross numerous biological barriers. Combined with other biomaterials, hybrid and multitasking chitosan-based systems can be realized for many applications. These include controlled drug release, targeted drug delivery, post-surgery implants (immunovaccines), theranostics, biosensing of tumor-derived circulating materials, multimodal systems, and combination therapy platforms with the potential to eliminate bulk tumors as well as lingering tumor cells to treat minimal residual disease (MRD) and recurrent cancer. We first introduce different formats, derivatives, and properties of chitosan. Next, given the barriers to therapeutic efficacy in solid tumors, we review advanced formulations of chitosan modules as efficient drug delivery systems to overcome tumor heterogeneity, multi-drug resistance, MRD, and metastasis. Finally, we discuss chitosan NPs for clinical translation and treatment of recurrent cancer and their future perspective.

3D Bioprinted Chitosan-Based Hydrogel Scaffolds in Tissue Engineering and Localised Drug Delivery

Bioprinting is an emerging technology with various applications in developing functional tissue constructs for the replacement of harmed or damaged tissues and simultaneously controlled drug delivery systems (DDSs) for the administration of several active substances, such as growth factors, proteins, and drug molecules. It is a novel approach that provides high reproducibility and precise control over the fabricated constructs in an automated way. An ideal bioink should possess proper mechanical, rheological, and biological properties essential to ensure proper function. Chitosan is a promising natural-derived polysaccharide to be used as ink because of its attractive properties, such as biodegradability, biocompatibility, low cost, and non-immunogenicity. This review focuses on 3D bioprinting technology for the preparation of chitosan-based hydrogel scaffolds for the regeneration of tissues delivering either cells or active substances to promote restoration.

Chitosan-based biomaterials for the treatment of bone disorders

Bone is an alive and dynamic organ that is well-differentiated and originated from mesenchymal tissues. Bone undergoes continuous remodeling during the lifetime of an individual. Although knowledge regarding bones and their disorders has been constantly growing, much attention has been devoted to effective treatments that can be used, both from materials and medical performance points of view. Polymers derived from natural sources, for example polysaccharides, are generally biocompatible and are therefore considered excellent candidates for various biomedical applications. This review outlines the development of chitosan-based biomaterials for the treatment of bone disorders including bone fracture, osteoporosis, osteoarthritis, arthritis rheumatoid, and osteosarcoma. Different examples of chitosan-based formulations in the form of gels, micro/nanoparticles, and films are discussed herein. The work also reviews recent patents and important developments related to the use of chitosan in the treatment of bone disorders. Although most of the cited research was accomplished before reaching the clinical application level, this manuscript summarizes the latest achievements within chitosan-based biomaterials used for the treatment of bone disorders and provides perspectives for future scientific activities.

Chitosan derivatives functionalized dual ROS-responsive nanocarriers to enhance synergistic oxidation-chemotherapy

The efficient triggering of prodrug release has become a challengeable task for stimuli-responsive nanomedicine utilized in cancer therapy due to the subtle differences between normal and tumor tissues and heterogeneity. In this work, a dual ROS-responsive nanocarriers with the ability to self-regulate the ROS level was constructed, which could gradually respond to the endogenous ROS to achieve effective, hierarchical and specific drug release in cancer cells. In brief, DOX was conjugated with MSNs via thioketal bonds and loaded with β-Lapachone. TPP modified chitosan was then coated to fabricate nanocarriers for mitochondria-specific delivery. The resultant nanocarriers respond to the endogenous ROS and release Lap specifically in cancer cells. Subsequently, the released Lap self-regulated the ROS level, resulting in the specific DOX release and mitochondrial damage in situ, enhancing synergistic oxidation-chemotherapy. The tumor inhibition Ratio was achieved to 78.49%. The multi-functional platform provides a novel remote drug delivery system in vivo.

Amphiphilic Chitosan Bearing Double Palmitoyl Chains and Quaternary Ammonium Moieties as a Nanocarrier for Plasmid DNA

Amphiphilic chitosan, bPalm-CS-HTAP, having N-(2-((2,3-bis(palmitoyloxy)propyl)amino)-2-oxoethyl) (bPalm) groups as double hydrophobic tails and O-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) groups as hydrophilic heads was synthesized and evaluated for its self-assembly properties and potential as a gene carrier. The degree of bis-palmitoyl group substitution (DS _bPalm) and the degree of quaternization (DQ) were approximately 2 and 56%, respectively. bPalm-CS-HTAP was found to assemble into nanosized spherical particles with a hydrodynamic diameter (D _H) of 265.5 ± 7.40 nm (PDI = 0.5) and a surface charge potential of 40.1 ± 0.04 mV. bPalm-CS-HTAP condensed the plasmid pVAX1.CoV2RBDme completely at a bPalm-CS-HTAP:pDNA ratio of 2:1. The self-assembled bPalm-CS-HTAP/pDNA complexes could enter HEK 293A and CHO cells and enabled gene expression at negligible cytotoxicity compared to commercial PEI (20 kDa). These results suggested that bPalm-CS-HTAP can be used as a promising nonviral gene carrier.

Near-Infrared Fluorescence Tumor-Targeted Imaging in Lung Cancer: A Systematic Review

Lung cancer is the most common cancer type worldwide, with non-small cell lung cancer (NSCLC) being the most common subtype. Non-disseminated NSCLC is mainly treated with surgical resection. The intraoperative detection of lung cancer can be challenging, since small and deeply located pulmonary nodules can be invisible under white light. Due to the increasing use of minimally invasive surgical techniques, tactile information is often reduced. Therefore, several intraoperative imaging techniques have been tested to localize pulmonary nodules, of which near-infrared (NIR) fluorescence is an emerging modality. In this systematic review, the available literature on fluorescence imaging of lung cancers is presented, which shows that NIR fluorescence-guided lung surgery has the potential to identify the tumor during surgery, detect additional lesions and prevent tumor-positive resection margins.

Synergistic antimicrobial interactions of nisin A with biopolymers and solubilising agents for oral drug delivery

In order to develop bacteriocins, like the lantibiotic nisin A, into effective alternatives to existing antibiotics, their biophysical and physicochemical properties must first be assessed, from solubility, to susceptibility and absorption. It has been well established that formulation strategies at early drug development stages can be crucial for successful outcomes during preclinical and clinical phases of development, particularly for molecules with challenging physicochemical properties. This work elucidates the physicochemical challenges of nisin A in terms of its susceptibility to digestive enzymes like pepsin, pancreatin and proteinase K and its poor solubility at physiological pHs. Low solution concentrations, below the minimum inhibitory concentration against Staphylococcus aureus, were obtained in phosphate buffered saline (PBS, pH 7.4) and in fasted state simulated intestinal fluid (FaSSIF, pH 6.5), while higher solubilities at more acidic pH's such as in a KCl/HCl buffer (pH 2) and in fasted state simulated gastric fluid (FaSSGF, pH 1.6) are observed. Tween® 80 (0.01% v/v) significantly increased the solution concentration of nisin A in PBS (pH 7.4, 24 hr). Pancreatin doubled nisin A's solution concentration at pH 7.4 (PBS) but reduced its' inhibitory activity to ∼ 20%, and pepsin almost completely degraded nisin (after 24 hr), but retained activity at biologically relevant exposure times (∼ 15 min). Harnessing synergism between nisin A and either glycol chitosan or ε-poly lysine, combined with the solubilizing effect of Tween®, increased the antimicrobial activity of nisin A six fold in an in vitro oral administration model.

Glycol Chitosan Functionalized with a Gd(III) Chelate as a Redox-responsive Magnetic Resonance Imaging Probe to Label Cell Embedding Alginate Capsules

One possibility for the non-invasive imaging of encapsulated cell grafts is to label the lumen of cell embedding capsules with a redox-responsive probe, as an increased extracellular reducing potential can be considered as a marker of hypoxia-induced necrosis. A Gd(III)-HPDO3A-like chelate has been conjugated to glycol-chitosan through a redox-responsive disulphide bond to obtain a contrast agent for Magnetic Resonance Imaging (MRI). Such a compound can be interspersed with fibroblasts within the lumen of alginate-chitosan capsules. Increasing reducing conditions within the extracellular microenvironment lead to the reductive cleavage of the disulphide bond and to the release of gadolinium in the form of a low molecular weight, non-ionic chelate. The efflux of such chelate from capsules is readily detected by a decrease of contrast enhancement in T₁ -weighted MR images.

Visible light-curable water-soluble chitosan derivative, chitosan hydrogel, and preparation method: a patent evaluation of US2019202998A1

Introduction: Water soluble polysaccharides are versatile structural materials that can be used for the design of biocompatible hydrogels and wet dressings in wound healing applications. Glycol chitosan (GC) is an example of a multifunctional water-soluble chitosan derivative that has inherent wound healing properties and reactive sites for chemical modification.Areas covered: United States (US) patent US2019202998A1 describes the preparation of a novel wound healing technology based on a three-dimensional (3D) crosslinked GC hydrogel (GCH) wet dressing, prepared via the synthesis of PEG1K-biscarboxylic acid-g-Glycol Chitosan-g-methacrylate using visible light induced photocrosslinking. The selected polymeric network enables the encapsulation of additional growth factors or bioactives on reactive sites. Wet dressings in US2019202998A1 were evaluated against a commercially available control for in vitro release, cytotoxicity, and in vivo wound healing ability in a preliminary mouse model, with the overall wound healing performance consistent with related GC-based hydrogels.Expert opinion: Comprehensive biocompatibility and antimicrobial testing of the hydrogel is not reported in US2019202998A1, and is recommended as further work to enable clinical applicability. The invention disclosed in US2019202998A1 can potentially be integrated with 3D bioprinting and sensor technology for the preparation of 'smart' hydrogel wound dressings, and is a potential area for future research.

Octanoyl glycol chitosan enhances the proliferation and differentiation of tonsil-derived mesenchymal stem cells

Biofunctional polymers have been widely used to enhance the proliferation and functionality of stem cells. Here, we report the development of a new biofunctional polymer, octanoyl glycol chitosan (OGC), and demonstrate its effects on the cell cycle and stem cell function using tonsil-derived mesenchymal stem cells (TMSCs). OGC treatment (100 μg/mL) significantly increased the proliferation of TMSCs, which could be attributed to cyclin D1 up-regulation in the G1 phase of the cell cycle. Additionally, OGC enhanced the ability of TMSCs to differentiate into adipocytes, chondrocytes, and osteoblasts. Taken together, this new biofunctional polymer, OGC, can promote stemness and osteogenesis, as well as induce stem cell proliferation by enhancing the intracellular metabolic rate and regulating the cell cycle. Thus, in the future, OGC could be a potential therapeutic additive for improving stem cell function.

Hydrophobically modified PEGylated glycol chitosan nanoparticles: synthesis, characterisation and anticancer properties

A novel palmitoylated glycol chitosan polymer grafted with PEG (PGC-PEG) was successfully developed to form amphiphilic micelles in aqueous solution.

Photostable AIE probes for wash-free, ultrafast, and high-quality plasma membrane staining

Plasma membrane (PM), a fundamental building component of a cell, is responsible for a variety of cell functions and biological processes. However, it is still challenging to acquire its morphology and morphological variation information via an effective approach. Herein, we report a PM imaging study regarding an aggregation-induced emission luminogen (AIEgen) called tetraphenylethylene-naphthalimide+ (TPE-NIM+), which is derived from our previously reported tetraphenylethylene-naphthalimide (TPE-NIM). The designed AIEgen (TPE-NIM+) shows significant characteristics of ultrafast staining, high photostability, wash-free property, and long retention time at the PM, which can structurally be correlated with its positively charged quaternary amine and hydrophobic moiety. TPE-NIM+ is further applied for staining of different cell lines, proving its universal PM imaging capability. Most importantly, we demonstrate that TPE-NIM+ can clearly delineate the contours of densely packed living cells with high cytocompatibility. Therefore, TPE-NIM+ as a PM imaging reagent superior to currently available commercial PM dyes shall find a number of applications in the biological/biomedical fields and even beyond.

A Biocompatible, Stimuli-Responsive, and Injectable Hydrogel with Triple Dynamic Bonds

Injectable hydrogels have attracted growing interests as promising biomaterials for clinical applications, due to their minimum invasive implanting approach and easy-handling performance. Nevertheless, natural biomaterials-based injectable hydrogels with desirable nontoxicity are suffering from limited functions, failing to fulfill the requirements of clinical biomaterials. The development of novel injectable biomaterials with a combination of biocompatibility and adequate functional properties is a growing urgency toward biomedical applications. In this contribution, we report a simple and effective approach to fabricate multi-functional CMC-OSA-DTP hydrogels. Two kinds of natural polysaccharide derived polymers, carboxymethyl chitosan (CMC) and oxidized alginate (OSA) along with 3,3'-dithiopropionic acid dihydrazide (DTP) were utilized to introduce three dynamic covalent bonds. Owing to the existence of triple dynamic bonds, this unique CMC-OSA-DTP hydrogel possessed smart redox and pH stimuli-responsive property, injectability as well as self-healing ability. In addition, the CCK-8 and live/dead assays demonstrated satisfying cytocompatibility of the CMC-OSA-DTP hydrogel in vitro. Based on its attractive properties, this easy-fabricated and multi-functional hydrogel demonstrated the great potential as an injectable biomaterial in a variety of biomedical applications.

Chitosan-Based Drug Delivery System: Applications in Fish Biotechnology

Chitosan is increasingly used for safe nucleic acid delivery in gene therapy studies, due to well-known properties such as bioadhesion, low toxicity, biodegradability and biocompatibility. Furthermore, chitosan derivatization can be easily performed to improve the solubility and stability of chitosan-nucleic acid polyplexes, and enhance efficient target cell drug delivery, cell uptake, intracellular endosomal escape, unpacking and nuclear import of expression plasmids. As in other fields, chitosan is a promising drug delivery vector with great potential for the fish farming industry. This review highlights state-of-the-art assays using chitosan-based methodologies for delivering nucleic acids into cells, and focuses attention on recent advances in chitosan-mediated gene delivery for fish biotechnology applications. The efficiency of chitosan for gene therapy studies in fish biotechnology is discussed in fields such as fish vaccination against bacterial and viral infection, control of gonadal development and gene overexpression and silencing for overcoming metabolic limitations, such as dependence on protein-rich diets and the low glucose tolerance of farmed fish. Finally, challenges and perspectives on the future developments of chitosan-based gene delivery in fish are also discussed.