pH-responsive injectable polysaccharide hydrogels with self-healing, enhanced mechanical properties based on POSS

3D Printing of Hydrogel Polysaccharides for Biomedical Applications: A Review

Additive manufacturing, also known as 3D printing, is becoming more and more popular because of its wide range of materials and flexibility in design. Layer by layer, 3D complex structures can be generated by the revolutionary computer-aided process known as 3D bioprinting. It is particularly crucial for youngsters and elderly patients and is a useful tool for tailored pharmaceutical therapy. A lot of research has been carried out recently on the use of polysaccharides as matrices for tissue engineering and medication delivery. Still, there is a great need to create affordable, sustainable bioink materials with high-quality mechanical, viscoelastic, and thermal properties as well as biocompatibility and biodegradability. The primary biological substances (biopolymers) chosen for the bioink formulation are proteins and polysaccharides, among the several resources utilized for the creation of such structures. These naturally occurring biomaterials give macromolecular structure and mechanical qualities (biomimicry), are generally compatible with tissues and cells (biocompatibility), and are harmonious with biological digesting processes (biodegradability). However, the primary difficulty with the cell-laden printing technique (bioprinting) is the rheological characteristics of these natural-based bioinks. Polysaccharides are widely used because they are abundant and reasonably priced natural polymers. Additionally, they serve as excipients in formulations for pharmaceuticals, nutraceuticals, and cosmetics. The remarkable benefits of biological polysaccharides-biocompatibility, biodegradability, safety, non-immunogenicity, and absence of secondary pollution-make them ideal 3D printing substrates. The purpose of this publication is to examine recent developments and challenges related to the 3D printing of stimuli-responsive polysaccharides for site-specific medication administration and tissue engineering.

Degradable chiral mesoporous silica nanoparticles and carboxymethyl chitosan/cystamine hydrogels for selective loading and controlled release of S-naproxen

Degradable chiral mesoporous silica nanoparticles (DCMSN) are synthesized for selective loading and controlled release of S-naproxen (S-NPX). Chiral silane coupling agent (APTES-L) and degradable silane coupling agent (APTES-CN) are synthesized, respectively, which are used for the synthesis of DCMSN. APTES-L endows the DCMSN with chirality, while APTES-CN endows the DCMSN with degradability. Owing to the same rotatory directions of DCMSN and S-NPX, the DCMSN can be used for the selective loading of S-NPX, and the higher selectivity of DCMSN toward S-NPX is further confirmed by the thermodynamic computations. Further, the S-NPX loaded DCMSN (DCMSN-S-NPX) is encapsulated in the hydrogels cross-linked by carboxymethyl chitosan (CMCS) and cystamine (Cys). The TEM characterization reveals that the DCMSN has a regular and spherical shape, and the BET analysis demonstrates that the DCMSN is a typical mesoporous material. The thermogravimetry reveals that the contents of the silane coupling agents in the DCMSN are about 23.9 %. The results of UV and circular dichroism (CD) spectra indicate a higher selectivity of DCMSN toward S-NPX. The release of S-NPX from the hydrogels is controlled by pH and glutathione (GSH), and the release of S-NPX follows a zero-order equation. Cytotoxicity assay indicates that the drug-free hydrogels have excellent biocompatibility.

Epidermal growth factor-incorporated hydrogen bond crosslinked hemostatic microparticles capable of timely response to accidental bleeding for prehospital rescue

Prehospital rescue of accidental massive bleeding is crucial for saving lives. However, currently available hemostatic materials are still in infancy in treating accidental bleeding due to the challenges in fully satisfying the complex outdoor hemostatic requirements. Herein, we designed an epidermal growth factor (EGF)- incorporated, microparticle-formed, high-strength, dynamic environment-stable hemostatic gel system for prehospital rescue. Carboxyl and dimethylamide were employed as the hydrogen bond (H-bond) groups and were carefully engineered into the microparticles (DHMs). We demonstrated that the unique H-bond crosslinked micronized structure enabled the DHM-based gelling system to adequately meet the outdoor hemostatic requirements. The stable H-bond groups allow the DHMs to be stored at room temperature and be easily carried around. The small sizes (150-250 μm) of the DHMs enabled the filling of irregular defects, and upon encountering water, these DHMs integrated into hydrogels (DHMs-gels) with high mechanical strength (1.61 MPa), strong tissue adhesiveness (66.5 kPa) and stable performance under dynamic environments. In vivo results showed that the EGF-incorporated DHMs-gels (DHMs-EGF gel) achieved a 100 % survival rate in a simulated rescue process and promoted wound healing. Simultaneously possessing multiple prehospital rescue-required properties, the hemostatic DHMs-EGF may become an effective tool for emergency rescue.

Preparation and characterization of vanillin-conjugated chitosan-stabilized emulsions via a Schiff-base reaction

In the current work, vanillin-conjugated chitosan stabilized emulsions (CSVAEs) were successfully prepared and its characterization and antibacterial properties were investigated. Under stirring condition, CSVAEs were produced by a Schiff base reaction between the vanillin aldehyde group and the chitosan active amino group. The CSVAEs were described through Fourier transform infrared spectroscopy, X-ray diffraction, ultraviolet spectrophotometry and thermogravimetric analysis, which demonstrated the generation of Schiff bases between vanillin and chitosan. Furthermore, the CSVAEs displayed differences at different pH values, indicating their potential as pH-responsive materials. By studying their release behavior, pH 4 was a critical point at which the properties of the CSVAEs changed. The antibacterial tests showed that the CSVAEs had good pH-responsive antibacterial abilities against Staphylococcus aureus and Escherichia coli.

Acid-induced Poria cocos alkali-soluble polysaccharide hydrogel: Gelation behaviour, characteristics, and potential application in drug delivery

Poria cocos alkali-soluble polysaccharide (PCAP), a water-insoluble β-glucan, is the main component of the total dried sclerotia of Poria cocos. However, its gelation behaviour and properties have yet to be comprehensively studied. In this study, an acid-induced physical hydrogel based on natural PCAP is fabricated. The acid-induced gelation in PCAP is explored with respect to the pH and polysaccharide concentration. PCAP hydrogels are formed in the pH range of 0.3-10.5, and the lowest gelation concentration is 0.4 wt%. Furthermore, dynamic rheological, fluorescence, and cyclic voltammetry measurements are performed to elucidate the gelation mechanism. The results reveal that hydrogen bonds and hydrophobic interactions play a dominant role in gel formation. Subsequently, the properties of the PCAP hydrogels are investigated using rheological measurements, scanning electron microscopy, gravimetric analysis, free radical scavenging, MTT assays, and enzyme-linked immunosorbent assays. The PCAP hydrogels exhibit a porous network structure and cytocompatibility, in addition to good viscoelastic, thixotropic, water-holding, swelling, antioxidant, and anti-inflammatory activities. Furthermore, using rhein as a model drug for encapsulation, it is demonstrated that its cumulative release behaviour from the PCAP hydrogel is pH dependent. These results indicate the potential of PCAP hydrogels for application in biological medicine and drug delivery.

Stimuli-Responsive Polysaccharide Hydrogels and Their Composites for Wound Healing Applications

There is a growing concern about wound care, since traditional dressings such as bandages and sutures can no longer meet existing needs. To address the demanding requirements, naturally occurring polymers have been extensively exploited for use in modern wound management. Polysaccharides, being the most abundant biopolymers, have some distinct characteristics, including biocompatibility and biodegradability, which render them ideal candidates for wound healing applications. Combining them with inorganic and organic moieties can produce effective multifunctional composites with the desired mechanical properties, high wound healing efficiencies and excellent antibacterial behavior. Recent research endeavors focus on the development of stimuli-responsive polysaccharide composites for biomedical applications. Polysaccharide composites, being sensitive to the local environment, such as changes of the solution temperature, pH, etc., can sense and react to the wound conditions, thus promoting an effective interaction with the wound. This review highlights the recent advances in stimuli-responsive polysaccharide hydrogels and their composites for use in wound healing applications. The synthetic approaches, physical, chemical, and biochemical properties as well as their function in wound healing will be discussed.

Polysaccharide-based nanocomposites for biomedical applications: a critical review

Polysaccharides (PSA) have taken specific position among biomaterials for advanced applications in medicine. Nevertheless, poor mechanical properties are known as the main drawback of PSA, which highlights the need for PSA modification. Nanocomposites PSA (NPSA) are a class of biomaterials widely used as biomedical platforms, but despite their importance and worldwide use, they have not been reviewed. Herein, we critically reviewed the application of NPSA by categorizing them into generic and advanced application realms. First, the application of NPSA as drug and gene delivery systems, along with their role in the field as an antibacterial platform and hemostasis agent is discussed. Then, applications of NPSA for skin, bone, nerve, and cartilage tissue engineering are highlighted, followed by cell encapsulation and more critically cancer diagnosis and treatment potentials. In particular, three features of investigations are devoted to cancer therapy, i.e., radiotherapy, immunotherapy, and photothermal therapy, are comprehensively reviewed and discussed. Since this field is at an early stage of maturity, some other aspects such as bioimaging and biosensing are reviewed in order to give an idea of potential applications of NPSA for future developments, providing support for clinical applications. It is well-documented that using nanoparticles/nanomaterials above a critical concentration brings about concerns of toxicity; thus, their effect on cellular interactions would become critical. We compared nanoparticles used in the fabrication of NPSA in terms of toxicity mechanism to shed more light on future challenging aspects of NPSA development. Indeed, the neutralization mechanisms underlying the cytotoxicity of nanomaterials, which are expected to be induced by PSA introduction, should be taken into account for future investigations.

Recent Advances in 3D Bioprinting: A Review of Cellulose-Based Biomaterials Ink

Cellulose-based biodegradable hydrogel proves to be excellently suitable for the medical and water treatment industry based on the expressed properties such as its flexible structure and broad compatibility. Moreover, their potential to provide excellent waste management from the unutilized plant has triggered further study on the advanced biomaterial applications. To extend the use of cellulose-based hydrogel, additive manufacturing is a suitable technique for hydrogel fabrication in complex designs. Cellulose-based biomaterial ink used in 3D bioprinting can be further used for tissue engineering, drug delivery, protein study, microalgae, bacteria, and cell immobilization. This review includes a discussion on the techniques available for additive manufacturing, bio-based material, and the formation of a cellulose-based hydrogel.

Self-Healing Silsesquioxane-Based Materials

This review is devoted to self-healing materials (SHM) containing polyhedral oligomeric silsesquioxanes (POSS) as building blocks. The synthetic approach can vary depending on the role POSS are expected to play in a given system. POSS (especially double-decker silsesquioxanes) can be grafted in side chains of a polymer backbone or used as segments of the main chain. Appropriate functionalization allows the formation of dynamic bonds with POSS molecules and makes them an active component of SHM, both as crosslinking agents and as factors that enhance the dynamics of macromolecules in the polymer matrix. The latter effect can be achieved by reversible release of bulky POSS cages or by the formation of separated inclusions in the polymer matrix through hydrophobic interactions and POSS aggregation. The unique properties of POSS-based self-healing systems make them interesting and versatile materials for various applications (e.g., repairable coatings, sealants, sensors, soft materials for tissue engineering, drug delivery, and wound healing).

Transcutaneous Drug Delivery Systems Based on Collagen/Polyurethane Composites Reinforced with Cellulose

Designing composites based on natural polymers has attracted attention for more than a decade due to the possibility to manufacture medical devices which are biocompatible with the human body. Herein, we present some biomaterials made up of collagen, polyurethane, and cellulose doped with lignin and lignin-metal complex, which served as transcutaneous drug delivery systems. Compared with base material, the compressive strength and the elastic modulus of biocomposites comprising lignin or lignin-metal complex were significantly enhanced; thus, the compressive strength increased from 61.37 to 186.5 kPa, while the elastic modulus increased from 0.828 to 1.928 MPa. The release of ketokonazole from the polymer matrix follows a Korsmeyer–Peppas type kinetics with a Fickian diffusion. All materials tested were shown to be active against pathogenic microorganisms. The mucoadhesiveness, bioadhesiveness, mechanical resistance, release kinetic, and antimicrobial activity make these biocomposites to be candidates as potential systems for controlled drug release.