Chitosan-catechol: A polymer with long-lasting mucoadhesive properties

Design and development of novel self-assembled catechol-modified bile acid conjugates as pH-responsive apical sodium-dependent bile acid transporter targeting nanoparticles

Catechol-based biomaterials demonstrate biocompatibility, making them suitable for a wide range of therapeutic applications when integrated into various molecular frameworks. However, the development of orally available catechol-based biomaterials has been hindered by significant pH variations and complex interactions in the gastrointestinal (GI) tract. In this study, we introduce a novel catechol-modified bile acid (CMBA), which is synthesized by anchoring the FDA-approved drug, ursodeoxycholic acid to the neurotransmitter dopamine. This modification could form a new apical sodium-dependent bile acid transporter (ASBT) inhibitor (ASBTi) due to the bile acid moiety. The computational analysis using the TRAnsient Pockets in Proteins (TRAPP) module, coupled with MD simulations, revealed that CMBA exhibits a strong binding affinity at residues 51-55 of ASBT with a low inhibitory constant (Ki) value. Notably, in slightly alkaline biological conditions, CMBA molecules self-assemble into carrier-free nanoparticles with an average size of 240.2 ± 44.2 nm, while maintaining their ability to bind with ASBT. When administered orally, CMBA accumulates in the ileum and liver over 24 h, exhibiting significant therapeutic effects on bile acid (BA) metabolism in a high-fat diet (HFD)-fed mouse model. This study underscores the therapeutic potential of the newly developed catechol-based, pH-responsive ASBT-inhibiting nanoparticles presenting a promising avenue for advancing therapy.

A dynamically cross-linked catechol-grafted chitosan/gelatin hydrogel dressing synergised with photothermal therapy and baicalin reduces wound infection and accelerates wound healing

Superior multifunctional hydrogel dressings are of considerable interest in wound healing. In clinical practice, it is useful to investigate hydrogel dressings that offer multifunctional benefits to expedite the process of wound healing. In this study, Catechol-grafted Chitosan, Gelatin, and Fe3+ as substrates to construct a hydrogel network. The network was dynamically cross-linked to form Ccg@Fe hydrogel substrate. Fe3O4 nanoparticles and baicalin, which possess antimicrobial and anti-inflammatory properties, were loaded onto the substrate to form a photothermal antibacterial composite hydrogel dressing (Ccg@Fe/Bai@Fe3O4 NPs). The Ccg@Fe hydrogel was characterised using Fourier transform infrared spectroscopy (FTIR) and Ultraviolet-visible spectrophotometry (UV-Vis). The morphological, mechanical, and adhesion properties of the hydrogel were determined using scanning electron microscopy (SEM) and a universal testing machine. The hydrogel's swelling, hemostasis, and self-healing properties were also evaluated. Additionally, the study determined the release rate of hydrogel-loaded antimicrobial and anti-inflammatory Baicalin (Ccg@Fe/Bai) and evaluated the photothermal antimicrobial properties of hydrogel-loaded Fe3O4 nanoparticles (Ccg@Fe/Bai@Fe3O4 NPs) through synergistic photothermal therapy (PTT). Histological staining of mice skin wound tissues using Masson and H&E revealed that the Ccg@Fe/Bai@Fe3O4 NPs hydrogel dressing demonstrated potential healing ability with the aid of PTT. The study suggests that this multifunctional hydrogel dressing has great potential for wound healing.

Biopolymer Drug Delivery Systems for Oromucosal Application: Recent Trends in Pharmaceutical R&D

Oromucosal drug delivery, both local and transmucosal (buccal), is an effective alternative to traditional oral and parenteral dosage forms because it increases drug bioavailability and reduces systemic drug toxicity. The oral mucosa has a good blood supply, which ensures that drug molecules enter the systemic circulation directly, avoiding drug metabolism during the first passage through the liver. At the same time, the mucosa has a number of barriers, including mucus, epithelium, enzymes, and immunocompetent cells, that are designed to prevent the entry of foreign substances into the body, which also complicates the absorption of drugs. The development of oromucosal drug delivery systems based on mucoadhesive biopolymers and their derivatives (especially thiolated and catecholated derivatives) is a promising strategy for the pharmaceutical development of safe and effective dosage forms. Solid, semi-solid and liquid pharmaceutical formulations based on biopolymers have several advantageous properties, such as prolonged residence time on the mucosa due to high mucoadhesion, unidirectional and modified drug release capabilities, and enhanced drug permeability. Biopolymers are non-toxic, biocompatible, biodegradable and may possess intrinsic bioactivity. A rational approach to the design of oromucosal delivery systems requires an understanding of both the anatomy/physiology of the oral mucosa and the physicochemical and biopharmaceutical properties of the drug molecule/biopolymer, as presented in this review. This review summarizes the advances in the pharmaceutical development of mucoadhesive oromucosal dosage forms (e.g., patches, buccal tablets, and hydrogel systems), including nanotechnology-based biopolymer nanoparticle delivery systems (e.g., solid lipid particles, liposomes, biopolymer polyelectrolyte particles, hybrid nanoparticles, etc.).

Improved antioxidant and anti-tubercular potential of liquiritigenin grafted on low molecular weight chitosan from gladius of Sepioteuthis lessoniana

Chitosan (CH) is natural abundant biopolymer present on earth after cellulose. CH can be functionalized by numerous functional groups such as amino and carboxyl groups, potential biologically active compounds. The functionalization of CH with polyphenols had a greater biological than non-grafted CH. In the present study, the polyphenolic compound liquiritigenin (LTG) is chemically functionalized on the low molecular weight chitosan (LMW-CH) (693.09 Da). This was extracted and irradiated with gamma radiation from the gladius of Sepioteuthis lessoniana. The grafted compound was to in vitro anti-oxidant employing physicochemical methods and characterization was made by spectroscopic methods. The degree of deacetylation (DDA) of the LMW-CH was detected in 74 % of the samples, and at higher concentrations (100 g/mL). LMW-CH grafted with LTG had improved water solubility (5 mg/mL), and was thermally stable upto 143.58 °C. Its molecular weight was 855.1 Da. In conclusion the in vitro antioxidant and the anti-tuberculosis (anti-TB) properties of the grafted samples were significantly (P < 0.001) increased compared to the unconjugated LMW-CH and LTG. Overall, functionalization of LTG with LMW-CH improved the anti-tuberculosis activity. Further studies are needed to explore the possibilities of its use in vivo models.

A Single-Component Janus Zwitterionic Hydrogel Patch with a Bionic Microstructure for Postoperative Adhesion Prevention

The development of anti-adhesion hydrogels for preventing postoperative adhesions is an ongoing challenge, particularly in achieving a balance between exceptional antifouling properties and effective in situ tissue retention. In this study, we propose a unique approach with the design of a single-component Janus zwitterionic hydrogel patch featuring a bionic microstructure. The Janus patches were prepared through free radical polymerization of sulfobetaine methacrylate with N, N'-methylenebis(2-propenamide) as the cross-linker. The incorporation of hexagonal facets separated by interconnecting grooves on one side imparts durable and reliable in situ retention capabilities to the Janus hydrogel patch when it is applied to traumatized tissues. The opposing flat surface exhibits outstanding resistance to bacteria, proteins, and cell adhesion, due to the superhydrophilicity and excellent antifouling characteristics of zwitterionic polymers. This dual functionality empowers the Janus hydrogel patch to mitigate adhesions between traumatized and surrounding tissues. The hexagonal and groove bionic microstructures facilitate rapid drainage, promoting swift contact with the tissue for increased adhesion strength, while independent hexagonal microfacets enhance the peeling energy. In an in vivo setting, Janus zwitterionic hydrogel patches with surface microstructures form mutually embedded structures with the cecum surface, minimizing the likelihood of slippage and detachment. Remarkably, in vivo experiments involving abdominal wall cecum injuries illustrate the Janus zwitterionic hydrogel patch's superior anti-adhesion effectiveness compared to commercial controls. Thus, the Janus hydrogel patch, distinguished by its bionic microstructure surface, presents substantial potential in the biomedical field for averting postoperative adhesions.

Mucoadhesive, antioxidant, and lubricant catechol-functionalized poly(phosphobetaine) as biomaterial nanotherapeutics for treating ocular dryness

Dry eye disease (DED) is associated with ocular hyperosmolarity and inflammation. The marketed topical eye drops for DED treatment often lack bioavailability and precorneal residence time. In this study, we investigated catechol-functionalized polyzwitterion p(MPC-co-DMA), composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) and dopamine methacrylamide (DMA) monomers, as potential topical nanotherapeutics for DED. The copolymers were synthesized via random free-radical copolymerization, producing different proportions of catecholic functionalization. All as-prepared polymer compositions displayed good ocular biocompatibility. At a feeding ratio of 1:1, p(MPC1-co-DMA1) can facilitate a robust mucoadhesion via Michael addition and/or Schiff base reaction, thus prolonging ocular residence time after 4 days of topical instillation. The hydration lubrication of MPC and radical-scavenging DMA endow the nano-agent to ease tear-film hyperosmolarity and corneal inflammation. A single dose of p(MPC1-co-DMA1) (1 mg/mL) after 4 days post-instillation can protect the cornea against reactive oxygen species, inhibiting cell apoptosis and the over-expression of pro-inflammatory factors (IL-6 and TNF-α). In clinical assessment, DED-induced rabbit eyes receiving p(MPC1-co-DMA1) could increase lacrimal fluid secretion by 5-fold higher than cyclosporine A. The catechol-functionalized polyzwitterion with enhanced lubricity, mucoadhesion, and anti-oxidation/anti-inflammation properties has shown high promise as a bioactive eye drop formulation for treating DED.

Enhancing Mucoadhesive Properties of Gelatin through Chemical Modification with Unsaturated Anhydrides

Gelatin is a water-soluble natural polyampholyte with poor mucoadhesive properties. It has traditionally been used as a major ingredient in many pharmaceuticals, including soft and hard capsules, suppositories, tissue engineering, and regenerative medicine. The mucoadhesive properties of gelatin can be improved by modifying it through conjugation with specific adhesive unsaturated groups. In this study, gelatin was modified by reacting with crotonic, itaconic, and methacrylic anhydrides in varying molar ratios to yield crotonoylated-, itaconoylated-, and methacryloylated gelatins (abbreviated as Gel-CA, Gel-IA, and Gel-MA, respectively). The successful synthesis was confirmed using 1H NMR, FTIR spectroscopies, and colorimetric TNBSA assay. The effect of chemical modification on the isoelectric point was studied through viscosity and electrophoretic mobility measurements. The evolution of the storage (G') and loss (G'') moduli was employed to determine thermoreversible gelation points of modified and unmodified gelatins. The safety of modified gelatin derivatives was assessed with an in vivo slug mucosal irritation test (SMIT) and an in vitro MTT assay utilizing human pulmonary fibroblasts cell line. Two different model dosage forms, such as physical gels and spray-dried microparticles, were prepared and their mucoadhesive properties were evaluated using a flow-through technique with fluorescent detection and a tensile test with ex vivo porcine vaginal tissues and sheep nasal mucosa. Gelatins modified with unsaturated groups exhibited superior mucoadhesive properties compared to native gelatin. The enhanced ability of gelatin modified with these unsaturated functional groups is due to the formation of covalent bonds with cysteine-rich subdomains present in the mucin via thiol-ene click Michael-type addition reactions occurring under physiologically relevant conditions.

Multiple Natural Polymers in Drug and Gene Delivery Systems

Natural polymers are organic compounds produced by living organisms. In nature, they exist in three main forms, including proteins, polysaccharides, and nucleic acids. In recent years, with the continuous research on drug and gene delivery systems, scholars have found that natural polymers have promising applications in drug and gene delivery systems due to their excellent properties such as biocompatibility, biodegradability, low immunogenicity, and easy modification. However, since the structure, physicochemical properties, pharmacological properties and biological characteristics of biopolymer molecules have not yet been entirely understood, further studies are required before large-scale clinical application. This review focuses on recent advances in the representative natural polymers such as proteins (albumin, collagen, elastin), polysaccharides (chitosan, alginate, cellulose) and nucleic acids. We introduce the characteristics of various types of natural polymers, and further outline the characterization methods and delivery forms of these natural polymers. Finally, we discuss possible challenges for natural polymers in subsequent experimental studies and clinical applications. It provides an important strategy for the clinical application of natural polymers in drug and gene delivery systems.

Intranasal mask for protecting the respiratory tract against viral aerosols

The spread of many infectious diseases relies on aerosol transmission to the respiratory tract. Here we design an intranasal mask comprising a positively-charged thermosensitive hydrogel and cell-derived micro-sized vesicles with a specific viral receptor. We show that the positively charged hydrogel intercepts negatively charged viral aerosols, while the viral receptor on vesicles mediates the entrapment of viruses for inactivation. We demonstrate that when displaying matched viral receptors, the intranasal masks protect the nasal cavity and lung of mice from either severe acute respiratory syndrome coronavirus 2 or influenza A virus. With computerized tomography images of human nasal cavity, we further conduct computational fluid dynamics simulation and three-dimensional printing of an anatomically accurate human nasal cavity, which is connected to human lung organoids to generate a human respiratory tract model. Both simulative and experimental results support the suitability of intranasal masks in humans, as the likelihood of viral respiratory infections induced by different variant strains is dramatically reduced.

Cationic Biopolymeric Scaffold of Chelating Nanohydroxyapatite Self-Regulates Intraoral Microenvironment for Periodontal Bone Regeneration

Periodontal bone defect is a common but longstanding healthcare issue since traditional bone grafts have limited functionalities in regulating complex intraoral microenvironments. Here, a porous cationic biopolymeric scaffold (CSC-g-nHAp) with microenvironment self-regulating ability was synthesized by chitosan-catechol chelating the Ca2+ of nanohydroxyapatite and bonding type I collagen. Chitosan-catechol's inherent antibacterial and antioxidant abilities endowed this scaffold with desirable abilities to eliminate periodontal pathogen infection and maintain homeostatic balances between free radical generation and elimination. Meanwhile, this scaffold promoted rat bone marrow stromal cells' osteogenic differentiation and achieved significant ectopic mineralization after 4 weeks of subcutaneous implantation in nude mice. Moreover, after 8 weeks of implantation in the rat critical-sized periodontal bone defect model, CSC-g-nHAp conferred 5.5-fold greater alveolar bone regeneration than the untreated group. This cationic biopolymeric scaffold could regulate the local microenvironment through the synergistic effects of its antibacterial, antioxidant, and osteoconductive activities to promote solid periodontal bone regeneration.

Dopamine-dependent functions of hyaluronic acid/dopamine/silk fibroin hydrogels that highly enhance N-acetyl-L-cysteine (NAC) delivered from nasal cavity to brain tissue through a near-infrared photothermal effect on the NAC-loaded hydrogels

Hyaluronic acid/silk fibroin (HA/SF or HS) hydrogels with remarkable mechanical characteristics have been reported as tissue engineering biomaterials. Herein, the addition of dopamine/polydopamine (DA/PDA) to HS hydrogels to develop multifunctional HA/PDA/SF (or HDS) hydrogels for the delivery of drugs such as N-acetyl-L-cysteine (NAC) from nasal to brain tissue is examined. Herein, DA-dependent functions of HDS hydrogels with highly adhesive forces, photothermal response (PTR) effects generated by near infrared (NIR) irradiation, and anti-oxidative effects were demonstrated. An in-vitro study shows that the HDS/NAC hydrogels could open tight junctions in the RPMI 2650 cell line, a model cell of the nasal mucosa, as demonstrated by the decreased values of transepithelial electrical resistance (TEER) and more discrete ZO-1 staining than those for the control group. This effect was markedly enhanced by NIR irradiation of the HDS/NAC-NIR hydrogels. Compared to the results obtained using NAC solution, an in-vivo imaging study (IVIS) in rats showed an approximately nine-fold increase in the quantity of NAC delivered from the nasal cavity to the brain tissue in the span of 2 h through the PTR effect generated by the NIR irradiation of the nasal tissue and administration of the HDS/NAC hydrogels. Herein, dopamine-dependent multifunctional HDS hydrogels were studied, and the nasal administration of HDS/NAC-NIR hydrogels with PTR effects generated by NIR irradiation was found to have significantly enhanced NAC delivery to brain tissues.

Facilitation of Cell Cycle and Cellular Migration of Rat Schwann Cells by O-Carboxymethyl Chitosan to Support Peripheral Nerve Regeneration

O-carboxymethyl chitosan (CM-chitosan), holds high potential as a valuable biomaterial for nerve guidance conduits (NGCs). However, the lack of explicit bioactivity on neurocytes and poor duration that does not match nerve repair limit the restorative effects. Herein, CM-chitosan-based NGC is designed to induce the reconstruction of damaged peripheral nerves without addition of other activation factors. CM-chitosan possesses excellent performance in vitro for nerve tissue engineering, such as increasing the organization of filamentous actin and the expression of phospho-Akt, and facilitating the cell cycle and migration of Schwann cells. Moreover, CM-chitosan exhibits increased longevity upon cross-linking (C-CM-chitosan) with 1, 4-Butanediol diglycidyl ether, and C-CM-chitosan fibers possess appropriate biocompatibility. In order to imitate the structure of peripheral nerves, multichannel bioactive NGCs are prepared from lumen fillers of oriented C-CM-chitosan fibers and outer warp-knitted chitosan pipeline. Implantation of the C-CM-chitosan NGCs to rats with 10-mm defects of peripheral nerves effectively improve nerve function reconstruction by increasing the sciatic functional index, decreasing the latent periods of heat tingling, enhancing the gastrocnemius muscle, and promoting nerve axon recovery, showing regenerative efficacy similar to that of autograft. The results lay a theoretical foundation for improving the potential high-value applications of CM-chitosan-based bioactive materials in nerve tissue engineering.

Catechol-chitosan/carboxymethylated cotton-based Janus hemostatic patch for rapid hemostasis in coagulopathy

Uncontrolled bleeding is the leading cause of death, and the death risk of bleeding from coagulopathy is even higher. By infusing the relevant coagulation factors, bleeding in patients with coagulopathy can be clinically treated. However, there are not many emergency hemostatic products accessible for coagulopathy patients. In response, a Janus hemostatic patch (PCMC/CCS) with a two-layer structure of partly carboxymethylated cotton (PCMC) and catechol-grafted chitosan (CCS) was developed. Ultra-high blood absorption (4000 %) and excellent tissue adhesion (60 kPa) were both displayed by PCMC/CCS. The proteomic analysis revealed that PCMC/CCS has significantly contributed to the creative generation of FV, FIX, and FX, as well as to the substantial enrichment of FVII and FXIII, re-paving the initially blocked coagulation pathway of coagulopathy to promote hemostasis. The in vivo bleeding model of coagulopathy demonstrated that PCMC/CCS was substantially more effective than gauze and commercial gelatin sponge at achieving hemostasis in just 1 min. The study provides one of the first investigations on procoagulant mechanisms in anticoagulant blood conditions. Rapid hemostasis in coagulopathy will be significantly affected by the results of this experiment.

pH-Mediated Mucus Penetration of Zwitterionic Polydopamine-Modified Silica Nanoparticles

Zwitterionic polymers have emerged as promising trans-mucus nanocarriers due to their superior antifouling properties. However, for pH-sensitive zwitterionic polymers, the effect of the pH microenvironment on their trans-mucus fate remains unclear. In this work, we prepared a library of zwitterionic polydopamine-modified silica nanoparticles (SiNPs-PDA) with an isoelectric point of 5.6. Multiple-particle tracking showed that diffusion of SiNPs-PDA in mucus with a pH value of 5.6 was 3 times faster than that in mucus with pH value 3.0 or 7.0. Biophysical analysis found that the trans-mucus behavior of SiNPs-PDA was mediated by hydrophobic and electrostatic interactions and hydrogen bonding between mucin and the particles. Furthermore, the particle distribution in the stomach, intestine, and lung demonstrated the pH-mediated mucus penetration behavior of the SiNPs-PDA. This study reveals the pH-mediated mucus penetration behavior of zwitterionic nanomaterials, which provides rational design strategies for zwitterionic polymers as nanocarriers in various mucus microenvironments.

Injectable Bioadhesive Hydrogels Scavenging ROS and Restoring Mucosal Barrier for Enhanced Ulcerative Colitis Therapy

Despite the progress in the therapy of ulcerative colitis (UC), long-lasting UC remission can hardly be achieved in the majority of UC patients. The key pathological characteristics of UC include an impaired mucosal barrier and local inflammatory infiltration. Thus, a two-pronged approach aiming at repairing damaged mucosal barrier and scavenging inflammatory mediators simultaneously might hold great potential for long-term remission of UC. A rectal formulation can directly offer preferential and effective drug delivery to inflamed colon. However, regular intestinal peristalsis and frequent diarrhea in UC might cause transient drug retention. Therefore, a bioadhesive hydrogel with strong interaction with intestinal mucosa might be preferable for rectal administration to prolong drug retention. Here, we designed a bioadhesive hydrogel formed by the cross-linking of sulfhydryl chondroitin sulfate and polydopamine (CS-PDA). The presence of PDA would ensure the mucosa-adhesive behavior, and the addition of CS in the hydrogel network was expected to achieve the restoration of the intestinal epithelial barrier. To scavenge the key player (excessive reactive oxygen species, ROS) in inflamed colon, sodium ferulic (SF), a potent ROS inhibitor, was incorporated into the CS-PDA hydrogel. After rectal administration, the SF-loaded CS-PDA hydrogel could adhere to the colonic mucosa to allow prolonged drug retention. Subsequently, sustained SF release could be achieved to persistently scavenge ROS in inflammatory areas. Meanwhile, the presence of CS would promote the restoration of the mucosal barrier. Ultimately, scavenging ROS and restoring the mucosal barrier could be simultaneously achieved via this SF-loaded bioadhesive hydrogel scaffold. Our two-pronged approach might provide new insight for effective UC treatment.

Tannic acid-coated cellulose nanocrystals with enhanced mucoadhesive properties for aquaculture

Mucoadhesion can be exploited as a strategy to target drug and nutrient delivery to the outer mucosal layers of fish in aquaculture farms. Cellulose nanocrystals (CNC) derived from cellulose pulp fibers can interact with the mucosal membranes via hydrogen bonding, however, their mucoadhesive properties are weak and should be enhanced. In this study, CNC were coated with tannic acid (TA), a plant polyphenol with excellent wet-resistant bioadhesive properties, to strengthen their mucoadhesive capability. The optimal CNC:TA mass ratio was determined to be 20:1. The modified CNCs were 190 ± 40 nm in length and 21 ± 4 nm wide and displayed excellent colloidal stability, with a zeta potential of -35 mV. Turbidity titrations and rheological measurements revealed that the modified CNC possessed superior mucoadhesive properties compared to pristine CNC. Modification with tannic acid introduced additional functional groups for stronger hydrogen bond formation and hydrophobic interactions with mucin, which was confirmed by a large reduction in viscosity enhancement values in the presence of chemical blockers (urea and Tween80). The enhanced mucoadhesion of the modified CNC could be utilized for the fabrication of a mucoadhesive drug delivery system to promote sustainable aquaculture practices.

How to Design Catechol-Containing Hydrogels for Cell Encapsulation Despite Catechol Toxicity

Catechol (cat) is a highly adhesive diphenol that can be chemically grafted to polymers such as chitosan (CH) to make them adhesive as well. However, catechol-containing materials experimentally show a large variability of toxicity, especially in vitro. While it is unclear how this toxicity emerges, most concerns are directed toward the oxidation of catechol into quinone that releases reactive oxygen species (ROS) which can, in turn, cause cell apoptosis through oxidative stress. To better understand the mechanisms at play, we examined the leaching profiles, hydrogen peroxide (H₂O₂) production, and in vitro cytotoxicity of several cat-chitosan (cat-CH) hydrogels that were prepared with different oxidation levels and cross-linking methods. To create cat-CH with different propensities toward oxidation, we grafted either hydrocaffeic acid (HCA, more prone to oxidation) or dihydrobenzoic acid (DHBA, less prone to oxidation) to the backbone of CH. Hydrogels were cross-linked either covalently, using sodium periodate (NaIO₄) to trigger oxidative cross-linking, or physically, using sodium bicarbonate (SHC). While using NaIO₄ as a cross-linker increased the oxidation levels of the hydrogels, it also significantly reduced in vitro cytotoxicity, H₂O₂ production, and catechol and quinone leaching in the media. For all gels tested, cytotoxicity could be directly related to the release of quinones rather than H₂O₂ production or catechol release, showing that oxidative stress may not be the main reason for catechol cytotoxicity, as other pathways of quinone toxicity come into play. Results also suggest that the indirect cytotoxicity of cat-CH hydrogels fabricated through carbodiimide chemistry can be reduced if (i) catechol groups are chemically bound to the polymer backbone to prevent leaching or (ii) the chosen cat-bearing molecule has a high resistance to oxidation. Coupled with the use of other cross-linking chemistries or more efficient purification methods, these strategies can be adopted to synthesize various types of cytocompatible cat-containing scaffolds.

Hydroxyethyl cellulose functionalised with maleimide groups as a new excipient with enhanced mucoadhesive properties

Hydroxyethylcellulose (HEC) is a non-ionic water-soluble polymer with poor mucoadhesive properties. The mucoadhesive properties of hydroxyethylcellulose can be improved by modifying it through conjugation with molecules containing maleimide groups. Maleimide groups interact with the thiol groups present in cysteine domains in the mucin via Michael addition reaction under physiological conditions to form a strong mucoadhesive bond. This will prolong the residence time of a dosage form containing this modified polymer and drug on mucosal surfaces. In this study HEC was modified by reaction with 4-bromophenyl maleimide in varying molar ratios and the successful synthesis was confirmed using ¹H NMR and FTIR spectroscopies. The safety of the newly synthesised polymer derivatives was assessed with in vivo planaria assays and in vitro MTT assay utilising Caco-2 cell line. The synthesized maleimide-functionalised HEC solutions were sprayed onto blank tablets to develop a model dosage form. The physical properties and mucoadhesive behavior of these tablets were evaluated using a tensile test with sheep buccal mucosa. The maleimide-functionalised HEC exhibited superior mucoadhesive properties compared to unmodified HEC.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

The Studies on Chitosan for Sustainable Development: A Bibliometric Analysis

Chitosan is a biocompatible polymer with vast applications in pharmacology, medicine, paper making, agriculture, and the food industry due to its low toxicity. Chitosan also plays an important role in the sustainable environment since chitosan is able to absorb greenhouse gases, harmful organic matter, and heavy ions. Therefore, this paper conducts a bibliometric analysis of chitosan for sustainable development using the Scopus database from 1976 to 2023. A performance analysis on the 8002 documents was performed with Harzing's Publish or Perish. Science mapping was conducted using VOSviewer. The annual publication on chitosan for sustainable development showed an upward trend in recent years as the annual publication peaked in 2022 with 1178 documents with most of the documents being articles and published in journals. Material science, chemistry, and engineering are tightly related subject areas. China had the highest publication of 1560 total documents while the United States had the most impactful publication with 55,019 total citations, 68.77 citations per document, 77.6 citations per cited document, h-index 110, and g-index of 211. India had the largest international collaboration with 572 total link strength. "International Journal of Biological Macromolecules", "Carbohydrate Polymers", and "Polymers" have been identified as the top three source titles that publish the most documents on chitosan for sustainable development. The emerging trends in chitosan on sustainable development focus on the application of chitosan as an antibacterial agent and biosorbent for contaminants, especially in water treatment.

Porous Scaffolds Based on Polydopamine/Chondroitin Sulfate/Polyvinyl Alcohol Composite Hydrogels

In this paper, porous scaffolds based on composite hydrogels were fabricated using polydopamine (PDA), chondroitin sulfate (CS), and polyvinyl alcohol (PVA) via the freezing/thawing method. Different characteristics of the prepared composite hydrogels, including the pore sizes, compression strength, lap shear strength, mass loss, and cytocompatibility were investigated. Scanning electron microscope images (SEM) displayed the hydrogel pore sizes, ranging from 20 to 100 μm. The composite hydrogel exhibited excellent porosity of 95.1%, compression strength of 5.2 MPa, lap shear strength of 21 kPa on porcine skin, and mass loss of 16.0%. In addition, the composite hydrogel possessed good relative cell activity of 97%. The PDA/CS/PVA hydrogel is cytocompatible as a starting point, and it can be further investigated in tissue engineering.

Nanochitin and Nanochitosan: Chitin Nanostructure Engineering with Multiscale Properties for Biomedical and Environmental Applications

Nanochitin and nanochitosan (with random-copolymer-based multiscale architectures of glucosamine and N-acetylglucosamine units) have recently attracted immense attention for the development of green, sustainable, and advanced functional materials. Nanochitin and nanochitosan are multiscale materials from small oligomers, rod-shaped nanocrystals, longer nanofibers, to hierarchical assemblies of nanofibers. Various physical properties of chitin and chitosan depend on their molecular- and nanostructures; translational research has utilized them for a wide range of applications (biomedical, industrial, environmental, and so on). Instead of reviewing the entire extensive literature on chitin and chitosan, here, recent developments in multiscale-dependent material properties and their applications are highlighted; immune, medical, reinforcing, adhesive, green electrochemical materials, biological scaffolds, and sustainable food packaging are discussed considering the size, shape, and assembly of chitin nanostructures. In summary, new perspectives for the development of sustainable advanced functional materials based on nanochitin and nanochitosan by understanding and engineering their multiscale properties are described.

Injectable polylysine and dextran hydrogels with robust antibacterial and ROS-scavenging activity for wound healing

Cutaneous wound management remains a major concern due to uncontrolled inflammation and bacterial infection in clinical care. A desirable hydrogel dressing with antibacterial and antioxidative properties can drive wound healing by inhibiting infection and inflammation. Herein, a multifunctional hydrogel based on polylysine-graft-cysteine (EPL-SH)/oxidized dextran (ODex) was fabricated for promoting skin tissue regeneration. The engineered hydrogel possessed versatile properties including tunable gelation time (60-300 s), typical rheological behavior, suitable swelling and degradation progress, injectable and self-healing ability. The unique hydrogels also displayed promising tissue adhesiveness, high cell affinity, excellent antioxidant and antimicrobial activity. Furthermore, the in vivo full-thickness skin defect experiment demonstrated the simple-to-implement injectable hydrogels could significantly promoting wound healing by improving the collagen deposition and angiogenesis. The manufacture of our multifunctional hydrogels dressing affords a new strategy for improving efficacy of cutaneous wound treatment.

Exploiting Polyelectrolyte Complexation for the Development of Adhesive and Bioactive Membranes Envisaging Guided Tissue Regeneration

Mussels secrete protein-based byssal threads to tether to rocks, ships, and other organisms underwater. The secreted marine mussel adhesive proteins (MAPs) contain the peculiar amino acid L-3,4-dihydroxyphenylalanine (DOPA), whose catechol group content contributes greatly to their outstanding adhesive properties. Inspired by such mussel bioadhesion, we demonstrate that catechol-modified polysaccharides can be used to obtain adhesive membranes using the compaction of polyelectrolyte complexes (CoPEC) method. It is a simple and versatile approach that uses polyelectrolyte complexes as building blocks that coalesce and dry as membrane constructs simply as a result of sedimentation and mild temperature. We used two natural and biocompatible polymers: chitosan (CHI) as a polycation and hyaluronic acid (HA) as a polyanion. The CoPEC technique also allowed the entrapment of ternary bioactive glass nanoparticles to stimulate mineralization. Moreover, combinations of these polymers modified with catechol groups were made to enhance the adhesive properties of the assembled membranes. Extensive physico-chemical characterization was performed to investigate the successful production of composite CoPEC membranes in terms of surface morphology, wettability, stability, mechanical performance, in vitro bioactivity, and cellular behavior. Considering the promising properties exhibited by the obtained membranes, new adhesives suitable for the regeneration of hard tissues can be envisaged.

Bio-Inspired Muco-Adhesive Polymers for Drug Delivery Applications

Muco-adhesive drug delivery systems continue to be one of the most studied for controlled pharmacokinetics and pharmacodynamics. Briefly, muco-adhesive polymers, can be described as bio-polymers that adhere to the mucosal (mucus) surface layer, for an extended residency period of time at the site of application, by the help of interfacial forces resulting in improved drug delivery. When compared to traditional drug delivery systems, muco-adhesive carriers have the potential to enhance therapeutic performance and efficacy, locally and systematically, in oral, rectal, vaginal, amongst other routes. Yet, the achieving successful muco-adhesion in a novel polymeric drug delivery solution is a complex process involving key physico-chemico-mechanical parameters such as adsorption, wettability, polymer chain length, inter-penetration and cross-linking, to list a few. Hence, and in light of accruing progress, evidence and interest, during the last decade, this review aims to provide the reader with an overview of the theories, principles, properties, and underlying mechanisms of muco-adhesive polymers for pharmaceutics; from basics to design to characterization to optimization to evaluation to market. A special focus is devoted to recent advances incorporating bio-inspired polymers for designing controlled muco-adhesive drug delivery systems.

Catechol-chitosan/polyacrylamide hydrogel wound dressing for regulating local inflammation

Chronic wounds and the accompanying inflammation are ongoing challenges in clinical treatment. They are usually accompanied by low pH and high oxidative stress environments, limiting cell growth and proliferation. Ordinary medical gauze has limited therapeutic effects on chronic wounds, and there is active research to develop new wound dressings. The chitosan hydrogel could be widely used in biomedical science with great biocompatibility, but the low mechanical properties limit its development. This work uses polyacrylamide to prepare double-network (DN) hydrogels based on bioadhesive catechol-chitosan hydrogels. Cystamine and N, N′-Bis(acryloyl)cystamine, which can be cross-linking agents with disulfide bonds to prepare redox-responsive DN hydrogels and pH-responsive nanoparticles (NPs) prepared by acetalized cyclodextrin (ACD) are used to intelligently release drugs against chronic inflammation microenvironments. The addition of catechol groups and ACD-NPs loaded with the Resolvin E1 (RvE1), promotes cell adhesion and regulates the inflammatory response at the wound site. The preparation of the DN hydrogel in this study can be used to treat and regulate the inflammatory microenvironment of chronic wounds accurately. It provides new ideas for using inflammation resolving factor loaded in DN hydrogel of good biocompatibility with enhanced mechanical properties to intelligent regulate the wound inflammation and promote the wound repaired.

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Dual-response hydrogel drug delivery system was used to intelligently release drugs at inflammation area of chronic wound.

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DN hydrogel was designed to enhance the properties of chitosan-based hydrogel with two cross-linking agents.

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Resolvin E1 loaded into wound dressing can help to regulate wound inflammation by regulating macrophage behavior.

Modular stimuli-responsive hydrogel sealants for early gastrointestinal leak detection and containment

Millions of patients every year undergo gastrointestinal surgery. While often lifesaving, sutured and stapled reconnections leak in around 10% of cases. Currently, surgeons rely on the monitoring of surrogate markers and clinical symptoms, which often lack sensitivity and specificity, hence only offering late-stage detection of fully developed leaks. Here, we present a holistic solution in the form of a modular, intelligent suture support sealant patch capable of containing and detecting leaks early. The pH and/or enzyme-responsive triggerable sensing elements can be read out by point-of-need ultrasound imaging. We demonstrate reliable detection of the breaching of sutures, in as little as 3 hours in intestinal leak scenarios and 15 minutes in gastric leak conditions. This technology paves the way for next-generation suture support materials that seal and offer disambiguation in cases of anastomotic leaks based on point-of-need monitoring, without reliance on complex electronics or bulky (bio)electronic implantables.

pH-Universal Catechol-Amine Chemistry for Versatile Hyaluronic Acid Bioadhesives

Catechol, a major mussel-inspired underwater adhesive moiety, has been used to develop functional adhesive hydrogels for biomedical applications. However, oxidative catechol chemistry for interpolymer crosslinking and adhesion is exclusively effective under alkaline conditions, with limited applications in non-alkaline conditions. To overcome this limitation, pH-universal catechol-amine chemistry to recapitulate naturally occurring biochemical events induced by pH variation in the mussel foot is suggested. Aldehyde moieties are introduced to hyaluronic acid (HA) by partial oxidation, which enables dual-mode catechol tethering to the HA via both stable amide and reactive secondary amine bonds. Because of the presence of additional reactive amine groups, the resultant aldehyde-modified HA conjugated with catechol (AH-CA) is effectively crosslinked in acidic and neutral pH conditions. The AH-CA hydrogel exhibits not only fast gelation via active crosslinking regardless of pH conditions, but also strong adhesion and excellent biocompatibility. The hydrogel enables rapid and robust wound sealing and hemostasis in neutral and alkaline conditions. The hydrogel also mediates effective therapeutic stem cell and drug delivery even in dynamic and harsh environments, such as a motile heart and acidic stomach. Therefore, the AH-CA hydrogel can serve as a versatile biomaterial in a wide range of pH conditions in vivo.

Mussel‐Inspired Biomaterials: From Chemistry to Clinic

After several billions of years, nature still makes decisions on its own to identify, develop, and direct the most effective material for phenomena/challenges faced. Likewise, and inspired by the nature, we learned how to take steps in developing new technologies and materials innovations. Wet and strong adhesion by Mytilidae mussels (among which Mytilus edulis—blue mussel and Mytilus californianus—California mussel are the most well‐known species) has been an inspiration in developing advanced adhesives for the moist condition. The wet adhesion phenomenon is significant in designing tissue adhesives and surgical sealants. However, a deep understanding of engaged chemical moieties, microenvironmental conditions of secreted proteins, and other contributing mechanisms for outstanding wet adhesion mussels are essential for the optimal design of wet glues. In this review, all aspects of wet adhesion of Mytilidae mussels, as well as different strategies needed for designing and fabricating wet adhesives are discussed from a chemistry point of view. Developed muscle‐inspired chemistry is a versatile technique when designing not only wet adhesive, but also, in several more applications, especially in the bioengineering area. The applications of muscle‐inspired biomaterials in various medical applications are summarized for future developments in the field.

Aldehyde-functional thermoresponsive diblock copolymer worm gels exhibit strong mucoadhesion

A series of thermoresponsive diblock copolymer worm gels is prepared via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate using a water-soluble methacrylic precursor bearing pendent cis-diol groups. Selective oxidation using an aqueous solution of sodium periodate affords the corresponding aldehyde-functional worm gels. The aldehyde groups are located within the steric stabilizer chains and the aldehyde content can be adjusted by varying the periodate/cis-diol molar ratio. These aldehyde-functional worm gels are evaluated in terms of their mucoadhesion performance with the aid of a fluorescence microscopy-based assay. Using porcine urinary bladder mucosa as a model substrate, we demonstrate that these worm gels offer a comparable degree of mucoadhesion to that afforded by chitosan, which is widely regarded to be a ‘gold standard’ positive control in this context. The optimum degree of aldehyde functionality is approximately 30%: lower degrees of functionalization lead to weaker mucoadhesion, whereas higher values compromise the desirable thermoresponsive behavior of these worm gels.

Optimizing the aldehyde content of thermoresponsive diblock copolymer worm gels via periodate oxidation leads to mucoadhesion performance comparable to that of chitosan (a gold standard positive control) in a fluorescence assay using porcine mucosa.

From Static to Dynamic: A Review on the Role of Mucus Heterogeneity in Particle and Microbial Transport

Mucus layers (McLs) are on the front line of the human defense system that protect us from foreign abiotic/biotic particles (e.g., airborne virus SARS-CoV-2) and lubricates our organs. Recently, the impact of McLs on human health (e.g., nutrient absorption and drug delivery) and diseases (e.g., infections and cancers) has been studied extensively, yet their mechanisms are still not fully understood due to their high variety among organs and individuals. We characterize these variances as the heterogeneity of McLs, which lies in the thickness, composition, and physiology, making the systematic research on the roles of McLs in human health and diseases very challenging. To advance mucosal organoids and develop effective drug delivery systems, a comprehensive understanding of McLs' heterogeneity and how it impacts mucus physiology is urgently needed. When the role of airway mucus in the penetration and transmission of coronavirus (CoV) is considered, this understanding may also enable a better explanation and prediction of the CoV's behavior. Hence, in this Review, we summarize the variances of McLs among organs, health conditions, and experimental settings as well as recent advances in experimental measurements, data analysis, and model development for simulations.

Surface Modification of Lipid-Based Nanoparticles

There is a growing interest in the development of lipid-based nanocarriers for multiple purposes, including the recent increase of these nanocarriers as vaccine components during the COVID-19 pandemic. The number of studies that involve the surface modification of nanocarriers to improve their performance (increase the delivery of a therapeutic to its target site with less off-site accumulation) is enormous. The present review aims to provide an overview of various methods associated with lipid nanoparticle grafting, including techniques used to separate grafted nanoparticles from unbound ligands or to characterize grafted nanoparticles. We also provide a critical perspective on the usefulness and true impact of these modifications on overcoming different biological barriers, with our prediction on what to expect in the near future in this field.

Novel Adhesive Nanocarriers Based on Mussel-Inspired Polyglycerols for the Application onto Mucosal Tissues

A synthetic route for adhesive core-multishell (CMS) nanocarriers for application to the oral mucosa was established using mussel-inspired catechol moieties. The three CMS nanocarriers with 8%, 13%, and 20% catechol functionalization were evaluated for loading capacity using Nile red, showing an overall loading of 1 wt%. The ability of Nile red loaded and functionalized nanocarriers to bind to a moist mucosal surface was tested in two complementary adhesion assays under static and dynamic conditions using monolayers of differentiated gingival keratinocytes. Adhesion properties of functionalized nanocarriers were compared to the adhesion of the non-functionalized nanocarrier. In both assays, the CMS nanocarrier functionalized with 8% catechol exhibited the strongest adhesion compared to its catechol-free counterpart and the CMS nanocarriers functionalized with 13% and 20% catechol.

Augmentation of Antidiabetic Activity of Glibenclamide Microspheres Using S-Protected Okra Powered by QbD: Scintigraphy and In Vivo Studies

Successful drug delivery by mucoadhesive systems depends on the polymer type, which usually gets adherent on hydration. The intended polymers must sustain the association with biomembranes and preserve or accommodate the drug for an extended time. The majority of hydrophilic polymers tend to make weak interactions like noncovalent bonds, which hampers the positioning of dosage forms at the required target sites, leading to inefficient therapeutic outcomes. It is possible to overcome this by functionalizing the natural polymers with thiol moiety. Further, considering that S-protected thiomers can benefit by improving thiol stability at a broad range of pH and enhancing the residence period at the required target, 2-mercapto-nicotinic acid (MA) was utilized in this present study to shield the free thiol groups on thiolated okra (TO). S-protected TO (STO) was synthesized and characterized for various parameters. Glibenclamide-loaded microspheres were formulated using STO (G-STO-M), and the process was optimized. The optimized formulation has shown complete and controlled release of the loaded drug at the end of the dissolution study. Cell viability assay indicated that the thiolated S-protected polymers gelated very well, and the formulated microspheres were safe. Further, G-STO-M showed considerable in vivo mucoadhesion strength. The glucose tolerance test confirmed the efficacy of STO formulation in minimizing the plasma glucose level. These results favor S-protection as an encouraging tool for improving the absorption of poorly aqueous soluble drugs like glibenclamide.

Facile anchoring mussel adhesive mimic tentacles on biodegradable polymer cargo carriers via self-assembly for microplastic-free cosmetics

Enhancing the deposition of fragrance delivery systems contained in personal care products on target surfaces is crucial for increasing the longevity of scent, efficiently utilizing expensive functional compounds and limiting the generation of microplastics in domestic waste water. In this work, we designed and synthesized a new type of biomimetic macromolecules, chitosan-graft-L-lysine-L-DOPA (C-L-D), as a versatile biodegradable adhesion promoter to facilitate the deposition of biodegradable fragrance carriers on diverse surfaces including hair, cotton and skin. The C-L-D has hyperbranched chain architecture with many oligopeptide adhesive tentacles, each being a simple mimic of mussel adhesive proteins. It also exhibits unique amphiphilic characteristic. As a result, it could be facilely anchored on cargo-loaded poly(lactic-co-glycolic acid) nanoparticle surface via self-assembly in the particle preparation process. The C-L-D-modified nanoparticles show significantly higher deposition efficiencies than polyvinyl alcohol- and chitosan-coated particles when deposited on the target surfaces in different aqueous media as the lysine and DOPA units are capable of providing multi-noncovalent interactions, including electrostatic, polar, hydrophobic interactions, and bidentate hydrogen bonds, with the target surfaces, and possibly also inducing oxidative cross-linking. A much higher retention rate of the C-L-D-modified nanoparticles on cotton surface is also observed after washing with a soap solution, which could be attributed to the significant role played by bidentate hydrogen bonds. These findings suggest that C-L-D is a versatile biodegradable adhesion promoter and has the potential to be applied for various personal care applications and beyond.

Dopamine-conjugated hyaluronic acid delivered via intra-articular injection provides articular cartilage lubrication and protection

Due to its high molecular weight and viscosity, hyaluronic acid (HA) is widely used for viscosupplementation to provide joint pain relief in osteoarthritis. However, this benefit is temporary due to poor adhesion of HA on articular surfaces. In this study, we therefore conjugated HA with dopamine to form HADN, which made the HA adhesive while retaining its viscosity enhancement capacity. We hypothesized that HADN could enhance cartilage lubrication through adsorption onto the exposed collagen type II network and repair the lamina splendens. HADN was synthesized by carbodiimide chemistry between hyaluronic acid and dopamine. Analysis of Magnetic Resonance (NMR) and Ultraviolet spectrophotometry (Uv-vis) showed that HADN was successfully synthesized. Adsorption of HADN on collagen was demonstrated using Quartz crystal microbalance with dissipation (QCM-D). Ex vivo tribological tests including measurement of coefficient of friction (COF), dynamic creep, in stance (40 N) and swing (4 N) phases of gait cycle indicated adequate protection of cartilage by HADN with higher lubrication compared to HA alone. HADN solution at the cartilage-glass sliding interface not only retains the same viscosity as HA and provides fluid film lubrication, but also ensures better boundary lubrication through adsorption. To confirm the cartilage surface protection of HADN, we visualized cartilage wear using optical coherence tomography (OCT) and atomic force microscopy (AFM).

Systematic Approach to Mimic Phenolic Natural Polymers for Biofabrication

In nature, phenolic biopolymers are utilized as functional tools and molecular crosslinkers to control the mechanical properties of biomaterials. Of particular interest are phenolic proteins/polysaccharides from living organisms, which are rich in catechol and/or gallol groups. Their strong underwater adhesion is attributed to the representative phenolic molecule, catechol, which stimulates intermolecular and intramolecular crosslinking induced by oxidative polymerization. Significant efforts have been made to understand the underlying chemistries, and researchers have developed functional biomaterials by mimicking the systems. Owing to their unique biocompatibility and ability to transform their mechanical properties, phenolic polymers have revolutionized biotechnologies. In this review, we highlight the bottom-up approaches for mimicking polyphenolic materials in nature and recent advances in related biomedical applications. We expect that this review will contribute to the rational design and synthesis of polyphenolic functional biomaterials and facilitate the production of related applications.

Spontaneous Gelation of Adhesive Catechol Modified Hyaluronic Acid and Chitosan

Spontaneously formed hydrogels are attracting increasing interest as injectable or wound dressing materials because they do not require additional reactions or toxic crosslinking reagents. Highly valuable properties such as low viscosity before external application, adequate filmogenic capacity, rapid gelation and tissue adhesion are required in order to use them for those therapeutic applications. In addition, biocompatibility and biodegradability are also mandatory. Accordingly, biopolymers, such as hyaluronic acid (HA) and chitosan (CHI), that have shown great potential for wound healing applications are excellent candidates due to their unique physiochemical and biological properties, such as moisturizing and antimicrobial ability, respectively. In this study, both biopolymers were modified by covalent anchoring of catechol groups, and the obtained hydrogels were characterized by studying, in particular, their tissue adhesiveness and film forming capacity for potential skin wound healing applications. Tissue adhesiveness was related to o-quinone formation over time and monitored by visible spectroscopy. Consequently, an opposite effect was observed for both polysaccharides. As gelation advances for HA-CA, it becomes more adhesive, while competitive reactions of quinone in CHI-CA slow down tissue adhesiveness and induce a detriment of the filmogenic properties.

All-in-One Theranostic Platform Based on Hollow Microcapsules for Intragastric-Targeting Antiulcer Drug Delivery, CT Imaging, and Synergistically Healing Gastric Ulcer

Bismuth-containing therapies are suggested as first-line and rescue alternatives for gastric ulcer (GU) treatment and Helicobacter pylori eradication. The current treatment strategy is called quadruple therapy and includes proton pump inhibitors, bismuth, and two broad-band antibiotics. This fact may affect medication compliance, leading to a resistance rate of more than 25% to clarithromycin or metronidazole. To counter this, from the perspective of natural products, an intragastric-targeting all-in-one theranostic platform is established: a drug carrier microcapsule composed of multiple synergistic antiulcer drugs, including bismuth, gallotannin, and antibiotics is obtained (BiG@MCs), and the therapeutic effects of BiG@MCs in rodent models are further evaluated. The results show that the BiG@MCs are spherical with homogeneous particle size (3 ± 0.5 µm) and can be response-released to the acidic environment of the stomach (pH 2.0-3.0), preventing the premature release of the BiG@MCs in physiological conditions. It is worth noting that the bismuth component can be easily identified by computed tomography and other detection instruments, which provide the possibility for drug tracing. In summary, these results indicate that BiG@MCs provide a versatile intragastric-targeting drug delivery platform for GU therapeutics.

Engineering Characteristics of Cement Composites Containing a Chitosan-Based Polymer and Steel Slag Aggregates

Recently, sustainable development has attracted significant global attention. Toward this, several studies have been performed on the development of alternative aggregates for mortar or concrete to prevent environmental damage and rapid depletion of natural aggregates. In this study, we investigated the applicability of a chitosan-based polymer (CBP), a biomimetic polymer, to cement mortar using steel slag as a fine aggregate. The CBP was synthesized via an amide coupling reaction among chitosan, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 3-(3,4-dihydroxyphenyl)propionic acid. Upon addition to cement mortar using natural sand or a blast furnace slag aggregate, the CBP contributed toward increasing the compressive strength and tensile strength. However, in mortar mixes using a ferronickel slag aggregate, the tensile strength decreased by ~5.7%–25.4% upon CBP addition. Moreover, the CBP reduced the total charge passed through the mixes. In particular, in the mortar mix using the steel slag aggregate, the CBP showed improved chloride-ion penetration resistance. The results showed that the as-prepared CBP was a suitable improving agent and exhibited promising compatibility with cement composites containing steel slag aggregates.

Synthesis and Validation of a Bioinspired Catechol-Functionalized Pt(IV) Prodrug for Preclinical Intranasal Glioblastoma Treatment

Simple Summary

Glioblastoma (GB) is a type of brain cancer with a poor prognosis and few improvements in its treatment. One of the greatest difficulties in GB therapy lies in the fact that most of the drugs with high anticancer potential do not reach the brain and exert high therapeutic activity while minimizing side effects. To overcome these limitations, we focused on a catechol-based Pt(IV) prodrug (able to reverse cisplatin in a cellular environment) with the intention of repurposing Pt-based drugs as GB chemotherapeutic agents. Our in vitro results have corroborated the therapeutic effect of the synthesized complexes as comparable to cisplatin, and in vivo studies have demonstrated the potential of nose-to-brain delivery of this Pt(IV) prodrug for GB treatment.

Abstract

Glioblastoma is the most malignant and frequently occurring type of brain tumors in adults. Its treatment has been greatly hampered by the difficulty to achieve effective therapeutic concentration in the tumor sites due to its location and the blood–brain barrier. Intranasal administration has emerged as an alternative for drug delivery into the brain though mucopenetration, and rapid mucociliary clearance still remains an issue to be solved before its implementation. To address these issues, based on the intriguing properties of proteins secreted by mussels, polyphenol and catechol functionalization has already been used to promote mucopenetration, intranasal delivery and transport across the blood–brain barrier. Thus, herein we report the synthesis and study of complex 1, a Pt(IV) prodrug functionalized with catecholic moieties. This complex considerably augmented solubility in contrast to cisplatin and showed a comparable cytotoxic effect on cisplatin in HeLa, 1Br3G and GL261 cells. Furthermore, preclinical in vivo therapy using the intranasal administration route suggested that it can reach the brain and inhibit the growth of orthotopic GL261 glioblastoma. These results open new opportunities for catechol-bearing anticancer prodrugs in the treatment for brain tumors via intranasal administration.

Preparation of External Stimulus-Free Gelatin-Catechol Hydrogels with Injectability and Tunable Temperature Responsiveness

Gelatin is one of the most versatile biopolymers in various biomedical applications. A gelatin derivative gelatin-catechol (Gel-C) was developed in this study to further optimize its chemical and physical properties such as thermal reversibility and injectability. We found that Gel-C remains in a solution state at room temperature, and the temperature-dependent gelation capability of gelatin is well preserved in Gel-C. Its gel-forming temperature decreased to about 10 °C (about 30 °C for gelatin), and a series of gelatin derivatives with different gel-forming temperatures (10-30 °C) were formed by mixing gelatin and Gel-C in different ratios. Additionally, irreversible Gel-C hydrogels could be made without the addition of external stimuli by combining the physical cross-linking of gelatin and the chemical cross-linking of catechol. At the same time, properties of Gel-C hydrogels such as thermal reversibility and injectability could be manipulated by controlling the temperature and pH of the precursor solution. By simulating the formation of an irreversible Gel-C hydrogel in vivo, an in situ gelling system was fabricated by lowering the local temperature of the hydrogel with cold shock, thus realizing targeted and localized molecular delivery with prolonged retention time. This simple system integrated with the temperature responsiveness of gelatin and chemical cross-linking of catechol groups thus provides a promising platform to fabricate an in situ gelling system for drug delivery.