Alginate derivatization: A review of chemistry, properties and applications

Anionic polysaccharides as delivery carriers for cancer therapy and theranostics: An overview of significance

Recently, cancer therapy has witnessed remarkable advancements with a growing focus on precision medicine and targeted drug delivery strategies. The application of anionic polysaccharides has gained traction in various drug delivery systems. Anionic polysaccharides have emerged as promising delivery carriers in cancer therapy and theranostics, offering numerous advantages such as biocompatibility, low toxicity, and the ability to encapsulate and deliver therapeutic agents to tumor sites with high specificity. This review underscores the significance of anionic polysaccharides as essential components of the evolving landscape of cancer therapy and theranostics. These polymers can be tailored to carry a wide range of therapeutic cargo, including chemotherapeutic agents, nucleic acids, and imaging agents. Their negative charge enables electrostatic interactions with positively charged drugs and facilitates the formation of stable nanoparticles, liposomes, or hydrogels for controlled drug release. Additionally, their hydrophilic nature aids in prolonging circulation time, reducing drug degradation, and minimizing off-target effects. Besides, some of them could act as targeting agents or therapeutic compounds that lead to improved therapeutic performance. This review offers valuable information for researchers, clinicians, and biomedical engineers. It provides insights into the recent progress in the applications of anionic polysaccharide-based delivery platforms in cancer theranostics to transform patient outcomes.

Natural biomaterials for sustainable flexible neuromorphic devices

Neuromorphic electronics use neural models in hardware to emulate brain-like behavior, and provide power-efficient, extremely compact, and massively-parallel processing, so they are ideal candidates for next-generation information-processing units. However, traditional rigid neuromorphic devices are limited by their unavoidable mechanical and geometrical mismatch with human tissues or organs. At the same time, the rapid development of these electronic devices has generated a large amount of electronic waste, thereby causing severe ecological problems. Natural biomaterials have mechanical properties compatible with biological tissues, and are environmentally benign, ultra-thin, and lightweight, so use of these materials can address these limitations and be used to create next-generation sustainable flexible neuromorphic electronics. Here, we explore the advantages of natural biomaterials in simulating synaptic behavior of sustainable neuromorphic devices. We present the flexibility, biocompatibility, and biodegradability of these neuromorphic devices, and consider the potential applicability of these properties in wearable and implantable bioelectronics. Finally, we consider the challenges of device fabrication and neuromorphic system integration by natural biomaterials, then suggest future research directions.

Acetylation of alginate enables the production of inks that mimic the chemical properties of P. aeruginosa biofilm

The reason why certain bacteria, e.g., Pseudomonas aeruginosa (PA), produce acetylated alginate (Alg) in their biofilms remains one of the most intriguing facts in microbiology. Being the main structural component of the secreted biofilm, like the one formed in the lungs of cystic fibrosis (CF) patients, Alg plays a crucial role in protecting the bacteria from environmental stress and potential threats. Nonetheless, to investigate the PA biofilm environment and its lack of susceptibility to antibiotic treatment, the currently developed in vitro biofilm models use native seaweed Alg, which is a non-acetylated Alg. The role of the acetyl side group on the backbone of bacterial Alg has never been elucidated, and the transposition of experimental results obtained from such systems to clinical conditions (e.g., to treat CF-infection) may be hazardous. We systematically investigated the influence of acetylation on the physico-chemical and mechanical properties of Alg in solution and Ca2+-crosslinked hydrogels. Furthermore, we assessed how the acetylation influenced the interaction of Alg with tobramycin, a common aminoglycoside antibiotic for PA. Our study revealed that the degree of acetylation directly impacts the viscosity and Young's Modulus of Alg in a pH-dependent manner. Acetylation increased the mesh size in biofilm-like Alg hydrogels, directly influencing antibiotic penetration. Our results provide essential insights to create more clinically relevant in vitro infection models to test the efficacy of new drugs or to better understand the 3D microenvironment of PA biofilms.

4D printing chemical stimuli-responsive hydrogels for tissue engineering and localized drug delivery applications - part 2

INTRODUCTION

The incorporation of 4D printing alongside chemical stimuli-responsive hydrogels represents a significant advancement in the field of biomedical engineering, effectively overcoming the constraints associated with conventional static 3D-printed structures. Through the integration of time as the fourth dimension, 4D printing facilitates the development of dynamic and adaptable structures that can react to chemical alterations in their surroundings. This innovation presents considerable promise for sophisticated tissue engineering and targeted drug delivery applications.

AREAS COVERED

This review examines the function of chemical stimuli-responsive hydrogels within the context of 4D printing, highlighting their distinctive ability to undergo regulated transformations when exposed to particular chemical stimuli. An in-depth examination of contemporary research underscores the collaborative dynamics between these hydrogels and their surroundings, focusing specifically on their utilization in biomimetic scaffolds for tissue regeneration and the advancement of intelligent drug delivery systems.

EXPERT OPINION

The integration of 4D printing technology with chemically responsive hydrogels presents exceptional prospects for advancements in tissue engineering and targeted drug delivery, facilitating the development of personalized and adaptive medical solutions. Although the potential is promising, it is essential to address challenges such as material optimization, biocompatibility, and precise control over stimuli-responsive behavior to facilitate clinical translation and scalability.

Form-Factor Control of Alginate Aerogels Via Thixotropic Sols: From Monoliths to Fibers to Films

Producing homogeneous alginate aerogel monoliths is challenging due to the uncontrollably fast gelation of sodium alginate (NaALG) solutions, which is typically induced with metal ions. This issue is overcome by decoupling molding from gelation. Aqueous NaALG solutions are first converted into thixotropic liquids via in situ acidification with acetic acid (AcOH) generated gradually through the hydrolysis of acetic anhydride (Ac2O), thus, providing time for casting in molds. The resulting solid-like thixotropic liquids are rigidized into wet gels conforming to the molds by a membraneless dialysis process via nonsolvent-induced phase separation, treatment with strong acids (HCl), or aqueous metal ion solutions (Ca2+, Cu2+, Fe3+, Ni2+, Ag+, Au3+). The thixotropic nature of the NaALG/Ac2O mixtures enables extrusion into fibers or spreading into films, followed by rigidization using the same methods. Wet gels in monolithic, fibrous, or film form were dried into aerogels with supercritical fluid (SCF) CO2. All aerogels were characterized by SEM, N2-sorption porosimetry, IR spectroscopy, solid-state CP MAS 13C NMR, and elemental analysis. Oscillatory rheology tracked the transition of NaALG to thixotropic liquids during Ac2O and AcOH titrations run in parallel. Thixotropic liquids from both titrations were rigidized with the nonsolvent-induced phase separation method and were processed into aerogels establishing that AcOH from the hydrolysis of Ac2O converts up to ∼30% mol/mol of NaALG to alginic acid (ALGH). Conversion of the remaining NaALG in thixotropic liquids to ALGH (>95% mol/mol) requires a strong acid (HCl), while rigidization with metal ions just replaces residual Na. Dynamic mechanical analysis (DMA) showed nearly identical storage moduli (E') for wet gels and aerogels, confirming that the solid network is formed during the rigidization step and is unaffected by subsequent processing. Notably, elemental analysis, porosimetry, and DMA data indicated that gels rigidized with Fe3+ included a secondary network, which, based on literature Mössbauer reports, is assigned to sol-gel-derived iron oxide.

Carboxyl-converting titration versus other methods for the uronic acid content analysis of alginate oligosaccharide

This study presents a carboxyl-conversing titration method for determining the uronic acid content of alginate oligosaccharide (AOS). All C6 carboxyl groups on the monosaccharide residues of AOS were initially converted into carboxylates, which were subsequently transformed into carbonates through carbonization and incineration. Quantification was finally done through acid titration. The AOS content, which was represented by the amount of monosaccharide residues (ManA and GulA residues) in AOS sample, was calculated based on the stoichiometric relationship between the C6 carboxyl group and monosaccharide residue. To evaluate its performance, the carboxyl-conversing titration method was compared with the sulfuric acid-carbazole method and 1-phenyl-3-methyl-5-pyrazolone (PMP) pre-column derivatization high performance liquid chromatography (PMP-HPLC) method. The content of the uronic acid in AOS sample were detected 96.24 % ± 0.42 % using the carboxyl-conversing titration method, 186.85 ± 0.49 % (ManA/GulA = 1/1 as the reference standard) using the sulfuric acid-carbazole method, and 3.00 ± 0.08 % using the PMP-HPLC method. The carboxyl-conversing titration method demonstrated the highest accuracy of the content value. The validation of this method was also confirmed in the terms of specificity, limits of detection and quantification, recovery, repeatability, intermediate precision and durability. Compared to the sulfuric acid-carbazole and PMP-HPLC methods, the carboxyl-conversing titration method was proved easy to operate, reliable, and independent of reference standards. This innovative method offers a promising solution for accurately determining AOS content in laboratory and industrial settings.

Advances in structure designing and function tailoring strategy toward alginate-based hydrogels for efficient water remediation: A review

Alginate (mainly sodium alginate, SA), as a natural polysaccharide material, has been widely applied in water remediation due to its excellent biocompatibility, degradability, and high hydration properties. Alginate hydrogels exhibit high adsorption capacity, effectively removing heavy metal ions, dyes, antibiotics, phosphate ions, and other pollutants from wastewater. This review begins with a description of the chemical structure of sodium alginate and its physicochemical properties, followed by a detailed discussion of the preparation methods of alginate-based composite hydrogels, including physical and chemical crosslinking, emulsification, electrostatic complexation, self-assembly, ultrasound and microwave-assisted methods. Based on the different compositions of the composites, alginate-based composite hydrogels are classified into several types for the removal of specific pollutants. Moreover, the paper systematically summarizes the research progress of alginate-based composite hydrogels in adsorbing heavy metal ions, dyes, antibiotics, phosphate ions for application effects. Although alginate-based composite hydrogels demonstrate great potential in water remediation, challenges such as insufficient mechanical strength, poor regeneration ability, and low stability under extreme conditions still exist. Finally, the future development prospects of alginate composite hydrogels in the field of water remediation, as well as potential research directions to improve their adsorption performance, enhance their regeneration capacity, and improve their environmental friendliness are presented.

Next-generation biopolymer gels: innovations in drug delivery and theranostics

Biopolymers or natural polymers like chitosan, cellulose, alginate, collagen, etc. have gained significant interest recently due to their remarkable tunable properties that make them appropriate for a variety of applications & play a crucial role in everyday life. The features of biopolymers which include biodegradability, biocompatibility, sustainability, affordability, & availability are vital for creating products for use in biomedical fields. Apart from these characteristics, smart or stimuli-responsive biopolymers also show a distinctive property of being susceptible to various factors like pH, temperature, light intensity, & electrical or magnetic fields. The current review would present a brief idea about smart biopolymer gels along with their biomedical applications. The use of smart biopolymers gels as theranostic agents are also discussed in the present review. This review also focuses on the application of biopolymers in the fields of drug delivery, cancer treatment, tissue engineering & wound healing. These areas demonstrate the development and utilization of different types of biopolymers in current biomedical applications.

Design, synthesis and biological evaluation of alginate oligosaccharide derivatives

To discover new potential drug for acute kidney injury (AKI), a series of novel alginate oligosaccharide derivatives were synthesized and characterized by the spectroscopic analysis. By using the controlled experimental method, the target compounds were evaluated preliminarily for therapeutic activity in AKI. The results demonstrated that compounds 2a, 2b, 2c and 3b exhibited notable inhibitory activity against the expression of related proteins at 250 μg/ml in vitro. Furthermore, the in vivo activity of 2a and 2b was found to be comparable to that of the trisaccharide (AOSC).

Carbohydrate polymer-based nanoparticles with cell membrane camouflage for cancer therapy: A review

Recent developments in biomimetic nanoparticles, specifically carbohydrate polymer-coated cell membrane nanoparticles, have demonstrated considerable promise in treating cancer. These systems improve drug delivery by imitating natural cell actions, enhancing biocompatibility, and decreasing immune clearance. Conventional drug delivery methods frequently face challenges with non-specific dispersal and immune detection, which can hinder their efficiency and safety. These biomimetic nanoparticles improve target specificity, retention times, and therapeutic efficiency by using biological components like chitosan, hyaluronic acid, and alginate. Chitosan-based nanoparticles, which come from polysaccharides found in nature, have self-assembly abilities that make them better drug carriers. Hyaluronic acid helps target tissues more effectively, especially in cancer environments where there are high levels of hyaluronic acid receptors. Alginate-based systems also enhance drug delivery by being biocompatible and degradable, making them ideal choices for advanced therapeutic uses. Moreover, these particles hold potential for overcoming resistance to multiple drugs and boosting the body's immune reaction to tumors through precise delivery and decreased side effects of chemotherapy drugs. This review delves into the possibilities of using carbohydrate polymer-functionalized nanoparticles and their impact on enhancing the efficacy of cancer treatment.

Bifunctional modified bacterial cellulose-based hydrogel through sequence-dependent crosslinking towards enhanced antibacterial and cutaneous wound healing

Chronic wounds caused by microbial infection have emerged as a major challenge on patients and medical health system. Bacterial cellulose (BC) characterized by its excellent biocompatibility and porous network, holds promise for addressing complex wound issues. However, lack of inherent antibacterial activity and cross-linking sites in the molecular network of BC have constrained its efficacy in hydrogel design and treatment of bacterial-infected wounds. Additionally, few studies have explored the effects of precursor crosslinking sequences on hydrogel processing. Herein, a quaternary ammonium and aldehyde-biofunctionalized bacterial cellulose (OQBC) was synthesized and utilized for the development of double network (DN) hydrogels, incorporating the crosslinking sequences of thiol-alginate (SASH) and carboxymethyl chitosan (CMCS). Firstly, OQBC was characterized with bifunctional groups, which endows its inherent antibacterial activity and gel-forming property. Subsequently, DN hydrogels formed through thiol-aldehyde addition and amino-aldehyde reactions showed favorable injectability and self-healing ability. The sequential crosslinking via Schiff-base and thiohemiacetal bonds endowed the hydrogels with distinct features, including degradation behavior, pH-responsive swelling, water retention, surface roughness, and cell behavior. With the increasing OQBC content into hydrogels, bacteriostatic rate exceeded 90 % without obvious cytotoxicity. Hydrogels also exhibited antioxidant and sustained drug release properties. Moreover, in infected skin thickness defect rats, the selected hydrogel enhanced wound repair and regeneration by inhibiting inflammation and promoting collagen deposition and angiogenesis. This design of sequence-dependent crosslinked antibacterial DN hydrogel offers a promising tool for the development of advanced materials to treat infected wounds.

Human mesenchymal stromal cells-laden crosslinked hyaluronic acid-alginate bioink for 3D bioprinting applications in tissue engineering

Three-dimensional (3D) bioprinting is considered one of the most advanced tools to build up materials for tissue engineering. The aim of this work was the design, development and characterization of a bioink composed of human mesenchymal stromal cells (hMSC) for extrusion through nozzles to create these 3D structures that might potentially be apply to replace the function of damaged natural tissue. In this study, we focused on the advantages and the wide potential of biocompatible biomaterials, such as hyaluronic acid and alginate for the inclusion of hMSC. The bioink was characterized for its physical (pH, osmolality, degradation, swelling, porosity, surface electrical properties, conductivity, and surface structure), mechanical (rheology and printability) and biological (viability and proliferation) properties. The developed bioink showed high porosity and high swelling capacity, while the degradation rate was dependent on the temperature. The bioink also showed negative electrical surface and appropriate rheological properties required for bioprinting. Moreover, stress-stability studies did not show any sign of physical instability. The developed bioink provided an excellent environment for the promotion of the viability and growth of hMSC cells. Our work reports the first-time study of the effect of storage temperature on the cell viability of bioinks, besides showing that our bioink promoted a high cell viability after being extruded by the bioprinter. These results support the suggestion that the developed hMSC-composed bioink fulfills all the requirements for tissue engineering and can be proposed as a biological tool with potential applications in regenerative medicine and tissue engineering.

Ethylenediamine-modified alginate - A hemocompatible platform for polymer-drug conjugates

The study is dedicated to the synthesis, rheological properties, hemocompatibility, and further modification of water-soluble derivatives of sodium alginate containing fragments of ethylenediamine (Alg-EDA). Alg-EDA with an equal ratio of amide/amine groups and varying degrees of substitution were synthesized by the carbodiimide method. The influence of the molecular weight of Alg-EDA on the attachment of bioactive molecules such as hydroxybenzoic and ferulic acids was determined. Modification of alginate with ethylenediamine fragments leads to a reduction in dynamic viscosity and sensitivity to Ca2+ ions (internal gelation method). Alg-EDA derivatives, with differ in molecular weight and degree of substitution with phenolic acids, are characterized by high hemocompatibility (in vitro tests: erythrocyte hemolysis, blood recalcification time, activated partial thromboplastin time). Antioxidant properties of the synthesized alginate derivatives were characterized using models of varying complexity (including cellular models). It was found that Alg-EDA, at a concentration of 0.5 mg/mL, had a statistically significant membrane-protective activity under conditions of acute oxidative stress induced by both H2O2 and AAPH. Derivatives with lower molecular weight were more effective than high molecular weight ones. Modification of polysaccharides by the fragments of phenolic acids into the structure contributed to the enhancement of antioxidant properties. The hemocompatible macromolecular antioxidants synthesized in this study are promising for further in-depth investigation for the creation of biomedical materials.

Synthetic Access to l-Guluronic Acid via Fluorine-Directed C-5 Epimerization

l-Guluronic acid is integral to the structures of alginates and to the pathogenesis of Pseudomonas aeruginosa. The exploitation of this hexose in both existing and new contexts is, however, limited by its prohibitively high commercial cost. We report on a short and efficient synthetic route to an l-GulA building block from a simple d-mannose thioglycoside. In this synthesis, the fluorine-directing effect is exploited to achieve a stereoselective C-5 epimerization. DFT calculations illuminate the substituent effects, which operate to confer this selectivity.

A bifunctional endolytic alginate lyase with two different lyase catalytic domains from Vibrio sp. H204

Alginate lyases can fully degrade alginate into various size-defined unsaturated oligosaccharide products by β-elimination. Here, we identified the bifunctional endolytic alginate lyase Aly35 from the marine bacterium Vibrio sp. Strain H204. The enzyme Aly35 is classified into the polysaccharide lyase 7 superfamily and contains two alginate lyase catalytic domains. The relationship and function of the two lyase domains are not well known. Thus, the full-length recombinant enzyme and its truncated proteins Aly35-CD1 (catalytic domain 1), Aly35-CD2 (catalytic domain 2 domain) were constructed. The three enzymes showed similar biochemical characteristics and exhibited temperature and pH stability. Further research showed that Aly35 and Aly35-CD2 can efficiently degrade alginate, polymannuronate (PM) and polyguluronate (PG) into a series of unsaturated oligosaccharides, while Aly35-CD1 exhibits greater PM-degrading activity than that of Aly35-CD2 but can not degraded PG efficiently. The results suggest that the domain (Trp295-His582) is critical for PG-degrading activity, the domain has (Leu53-Lys286) higher PM-degrading activity, both catalytic domains together confer increased alginate (including M-blocks and G blocks)-degrading activity. The enzyme Aly35 and its truncations Aly35-CD1 and Aly35-CD2 will be useful tools for structural analyses and for preparing bioactive oligosaccharides, especially Aly35-CD1 can be used to prepare G unit-rich oligosaccharides from alginate.

Recent opportunities and application of gellan gum based drug delivery system for intranasal route

OBJECTIVES

In the recent years, in-situ hydrogel based on gellan gum has been investigated for delivery of various drug molecules particularly to treat neurological disorders via intranasal route. The major objective of the present manuscript is to review the recent research studies exploring gellan gum as ionic triggered in-situ gel for intranasal administration to enhance absorption of drugs and to increase their therapeutic efficacy.

METHODS

This review include literature from 1982 to 2023 and were collected from various scientific electronic databases like Scopus, PubMed and Google Scholar to review source, chemistry, ionotropic gelation mechanism, and recent research studies for gellan gum based in-situ hydrogel for intransasl administration.Keywords such as gellan gum, in-situ hydrogel, intranasal administration and brain targeting were used to search literature. The present review included the research studies which explored gellan gum based in-situ gel for intranasal drug delivery.

RESULTS

The findings have shown enhanced biavailability of various drugs upon intranasal administration using gellan-gum based in-situ hydrogel.Moreover, the review indicated that intranasal administration of in-situ hydrogel facilitate to overcome blood brain barrier effectively. Hence, significantly higher drug concentration was found to be achieved in brain tissues upon intranasal administration than that of other routes like oral and intravenous.

CONCLUSION

The present work conducted a comprehensive review for gellan gum based in-situ hydrogel particularly for intransal administration to overcome BBB. The study concluded that gellan gum based in-situ hydrogel could be potential promising delivery system for intranasal administration to improve bioavailability and efficacy of drugs specifically to treat neurological disorders.

Physicochemical Properties, Drug Release and In Situ Depot-Forming Behaviors of Alginate Hydrogel Containing Poorly Water-Soluble Aripiprazole

The objective of this study was to investigate the physicochemical properties, drug release and in situ depot-forming behavior of alginate hydrogel containing poorly water-soluble aripiprazole (ARP) for achieving free-flowing injectability, clinically accessible gelation time and sustained drug release. The balanced ratio of pyridoxal phosphate (PLP) and glucono-delta-lactone (GDL) was crucial to modulate gelation time of the alginate solution in the presence of calcium carbonate. Our results demonstrated that the sol state alginate hydrogel before gelation was free-flowing, stable and readily injectable using a small 23 G needle. In addition, the ratio (w/w) of PLP and GDL altered the gelation time, which was longer as the PLP content increased but shorter as the GDL content increased. The alginate hydrogel with a ratio of PLP to GDL of 15:9 had the optimal physicochemical properties in terms of a clinically acceptable gelation time (9.1 min), in situ-depot formation with muscle-mimicking stiffness (3.55 kPa) and sustained release over a two-week period. The alginate hydrogel, which is tunable by varying the ratio of PLP and GDL, could provide a controllable pharmaceutical preparation to meet the need for long-acting performance of antipsychotic drugs like ARP.

Bioactive glass-polymer nanocomposites: a comprehensive review on unveiling their biomedical applications

Most natural and synthetic polymers are promising materials for biomedical applications because of their biocompatibility, abundant availability, and biodegradability. Their properties can be tailored according to the intended application by fabricating composites with other polymers or ceramics. The incorporation of ceramic nanoparticles such as bioactive glass (BG) and hydroxyapatite aids in the improvement of mechanical and biological characteristics and alters the degradation kinetics of polymers. BG can be used in the form of nanoparticles, nanofibers, scaffolds, pastes, hydrogels, or coatings and is significantly employed in different applications. This biomaterial is highly preferred because of its excellent biocompatibility, bone-stimulating activity, and favourable mechanical and degradation characteristics. Different compositions of nano BG are incorporated into the polymer system and studied for positive results such as enhanced bioactivity, better cell adherence, and proliferation rate. This review summarizes the fabrication and the progress of natural/synthetic polymer-nano BG systems for biomedical applications such as drug delivery, wound healing, and tissue engineering. The challenges and the future perspectives of the composite system are also addressed.

High-flexible chitosan-based composite membrane with multi-layer biopolymer coatings for anti-bacterial drug delivery and wound healing

Flexible chitosan-based membranes were prepared by casting/solvent evaporation method using chitosan flocks as raw material. To improve mechanical and biological properties, chitosan microspheres (CMs) were prepared and integrated to form the composite membranes. Two different anti-bacterial drugs, e.g., tetracycline hydrochloride (TH) and silver sulfadiazine (AgSD), were loaded into the CMs and composite membranes to enhance their anti-bacterial properties. Furthermore, composite membranes were alternately coated by multi-layers of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS) via the layer-by-layer self-assembly and Schiff-base cross-linking. Our results demonstrated that the microspheres and multi-layer coatings could improve the swelling, water vapor transmission and hydrophilicity of the composite membranes. The chitosan microspheres and multi-layer coatings increased the tensile strength and decreased the elongation at the break of the membranes. Our composite membrane had better mechanical properties, slow drug release, anti-bacterial properties, which could promote cell proliferation. This composite membrane has great application potential in inhibiting bacterial infection and promoting wound regeneration.

Sulfated Alginate for Biomedical Applications

Alginate (Alg) polymers have received much attention due to the mild conditions required for gel formation and their good bio-acceptability. However, due to limited interactions with cells, many drugs, and biomolecules, chemically modified alginates are of great interest. Sulfated alginate (S-Alg) is a promising heparin-mimetic that continues to be investigated both as a drug molecule and as a component of biomaterials. Herein, the S-Alg literature of the past five years (2017-2023) is reviewed. Several methods used to synthesize S-Alg are described, with a focus on new advances in characterization and stereoselectivity. Material fabrication is another focus and spans bulk materials, particles, scaffolds, coatings, and part of multicomponent biomaterials. The new application of S-Alg as an antitumor agent is highlighted together with studies evaluating safety and biodistribution. The high binding affinity of S-Alg for various drugs and heparin-binding proteins is exploited extensively in biomaterial design to tune the encapsulation and release of these agents and this aspect is covered in detail. Recommondations include publishing key material properties to allow reproducibility, careful selection of appropriate sulfation strategies, the use of cross-linking strategies other than ionic cross-linking for material fabrication, and more detailed toxicity and biodistribution studies to inform future work.

Eco-friendly ozonation of alginate: Physicochemical characterization and degradation mechanism exploration through mass spectrometry

The ozone degradation has been proven to be an effective degradation method for alginate, while the degradation mechanism remained to be unconfirmed. In this study, two high-molecular-weight alginates with different mannuronic/guluronic (G/M) ratios, HM and HG (G/M 0.49 vs 1.40), were depolymerized using established ozonation technology platform. Notably, HM can be degraded faster than HG especially within initial 30 min, indicating that the β-1, 4-mannuronic bonds are more susceptible to be ozonated than α-1, 4-guluronic bonds. However, HM/HG degraded to LMWA in 2 h and reached a plateau. Therefore, we employed mass spectrometry (MS) to profile the degraded products of LMWA polymannuronate (PM) and polyguluronate (PG) in more intense conditions. The results indicated that the oxidation process continued until all reducing ends were converted to carboxyl groups. The o-diol could directly oxidize to o-dialdehyde. This study provides a MS based elucidation of the mechanism by which alginate cleaves to oligosaccharides through ozonation.

Alginate-based hydrogels mediated biomedical applications: A review

With the development in the field of biomaterials, research on alternative biocompatible materials has been initiated, and alginate in polysaccharides has become one of the research hotspots due to its advantages of biocompatibility, biodegradability and low cost. In recent years, with the further understanding of microscopic molecular structure and properties of alginate, various physicochemical methods of cross-linking strategies, as well as organic and inorganic materials, have led to the development of different properties of alginate hydrogels for greatly expanded applications. In view of the potential application prospects of alginate-based hydrogels, this paper reviews the properties and preparation of alginate-based hydrogels and their major achievements in delivery carrier, dressings, tissue engineering and other applications are also summarized. In addition, the combination of alginate-based hydrogel and new technology such as 3D printing are also involved, which will contribute to further research and exploration.

Discovery and characterization of a novel poly-mannuronate preferred alginate lyase: The first member of a new polysaccharide lyase family

Alginate is one of the most important marine colloidal polysaccharides, and its oligosaccharides have been proven to possess diverse biological functions. Alginate lyases could specifically degrade alginate and therefore serve as desirable tools for the research and development of alginate. In this report, a novel catalytic domain, which demonstrated no significant sequence similarity with all previously defined functional domains, was verified to exhibit a random endo-acting lyase activity to alginate. The action pattern analysis revealed that the heterologously expressed protein, named Aly44A, preferred to degrade polyM. Its minimum substrates and the minimum products were identified as unsaturated alginate trisaccharides and disaccharides, respectively. Based on the sequence novelty of Aly44A and its homologs, a new polysaccharide lyase family (PL44) was proposed. The discovery of the novel enzyme and polysaccharide lyase family provided a new entrance for the gene-mining and acquiring of alginate lyases, and would facilitate to the utilization of alginate and its oligosaccharides.

Developing Advanced Antibacterial Alginic Acid Biomaterials through Dual Functionalization

This paper delves into the intersection of biomaterials and antibacterial agents, highlighting the importance of alginic acid-based biomaterials. We investigate enhancing antibacterial properties by functionalizing alginic acid with an ionic liquid and a potent chelating agent, tris(hydroxypyridinone) (THP). Initial functionalization with the ionic liquid markedly improves the material's antibacterial efficacy. Subsequent functionalization with THP further enhances this activity, reducing the minimum inhibitory concentration from 6 to 3 mg/mL. Notably, the newly developed dual-functionalized materials exhibit no cytotoxic effects at the concentrations tested, underscoring their potential for safe and effective antibacterial applications. These findings highlight the promising role of dual-functionalized alginic acid biomaterials in developing advanced antibacterial treatments.

pH-Responsive Alginate/Chitosan Gel Films: An Alternative for Removing Cadmium and Lead from Water

Biosorption, a non-expensive and easy method for removing potentially toxic metal ions from water, has been the subject of extensive research. In this context, this study introduces a novel approach using sodium alginate and chitosan, versatile biopolymers that have shown excellent results as biosorbents. The challenge of maintaining high efficiencies and reuse is addressed by developing alginate/chitosan-based films. These films, prepared using solvent casting and crosslinking methods, form a hydrogel network. The alginate/chitosan-based films, obtained using the eco-friendly polyelectrolyte complex method, were characterized by FTIR, SEM, TGA, and DSC. The study of their swelling pH response, adsorption, and desorption behavior revealed promising results. The adsorption of Pb was significantly enhanced by the presence of both biopolymers (98%) in a shorter time (15 min) at pH = 6.5. The adsorption of both ions followed a pseudo-second-order kinetic and the Langmuir isotherm model. The desorption efficiencies for Cd and Pb were 98.8% and 77.6% after five adsorption/desorption cycles, respectively. In conclusion, the alginate/chitosan-based films present a highly effective and novel approach for removing Cd and Pb from water, with a promising potential for reuse, demonstrating their strong potential in potentially toxic metal removal.

Dual-Self-Crosslinking Effect of Alginate-Di-Aldehyde with Natural and Synthetic Co-Polymers as Injectable In Situ-Forming Biodegradable Hydrogel

Injectable, in situ-forming hydrogels, both biocompatible and biodegradable, have garnered significant attention in tissue engineering due to their potential for creating adaptable scaffolds. The adaptability of these hydrogels, made from natural proteins and polysaccharides, opens up a world of possibilities. In this study, sodium alginate was used to synthesize alginate di-aldehyde (ADA) through periodate oxidation, resulting in a lower molecular weight and reduced viscosity, with different degrees of oxidation (54% and 70%). The dual-crosslinking mechanism produced an injectable in situ hydrogel. Initially, physical crosslinking occurred between ADA and borax via borax complexation, followed by chemical crosslinking with gelatin through a Schiff's base reaction, which takes place between the amino groups of gelatin and the aldehyde groups of ADA, without requiring an external crosslinking agent. The formation of Schiff's base was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. At the same time, the aldehyde groups in ADA were characterized using FT-IR, proton nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC), which determined its molecular weight. Furthermore, borax complexation was validated through boron-11 nuclear magnetic resonance (¹¹B NMR). The hydrogel formulation containing 70% ADA, polyethylene glycol (PEG), and 9% gelatin exhibited a decreased gelation time at physiological temperature, attributed to the increased gelatin content and higher degree of oxidation. Rheological analysis mirrored these findings, showing a correlation with gelation time. The swelling capacity was also enhanced due to the increased oxidation degree of PEG and the system's elevated gelatin content and hydrophilicity. The hydrogel demonstrated an average pore size of 40-60 µm and a compressive strength of 376.80 kPa. The lower molecular weight and varied pH conditions influenced its degradation behavior. Notably, the hydrogel's syringeability was deemed sufficient for practical applications, further enhancing its potential in tissue engineering. Given these properties, the 70% ADA/gelatin/PEG hydrogel is a promising candidate and a potential game-changer for injectable, self-crosslinking applications in tissue engineering. Its potential to revolutionize the field is inspiring and should motivate further exploration.

The role of alginate oligosaccharide on boar semen quality: A research review

Alginate is the general term of a polysaccharide which is widely used in the area of pharmaceutics and the food industry and is known for its unique biological activities. However, due to the low water solubility and large viscosity of alginate, its development and utilization in the agricultural field are limited. Alginate oligosaccharide (AOS) is a degradable product derived from alginate and has attracted much attention in recent years because of its specific characteristics such as a low molecular weight, high water solubility, and non-toxicity. Boar semen quality, which is affected by various factors, is an important indicator for measuring reproductive performance of boars. With the development of artificial insemination technology, high quality semen has been more and more important. Therefore, increasing semen quality is an important means to improve the reproductive performance in swine industry. In this research review, we used the PubMed database and Google Scholar and web of science to search for relevant literature on the topic of AOS in relation to boar semen quality. Key words used were alginate oligosaccharide, boars, semen quality, microbiota and metabolites. The purpose of this review article was to describe the current knowledge on the relationship between AOS and boar semen quality, and provide an overview of solutions for the decline in the boar semen quality in specific conditions. Based on the existing literature, it is evident that AOS can be used as a new type of food additive. This review paper provides a theoretical basis for the production of high-quality boar sperm and, suggests that, in the future, AOS can even aid in treating human infertility.

Preparation and Biochemical Activity of Copper-Coated Cellulose Nonwoven Fabric via Magnetron Sputtering and Alginate-Calcium Ion Complexation

Alginate-based materials have gained significant recognition in the medical industry due to their favorable biochemical properties. As a continuation of our previous studies, we have introduced a new composite consisting of cellulose nonwoven fabric charged with a metallic copper core (CNW-Cu0) covered with a calcium alginate (ALG-Ca2+) layer. The preparation process for these materials involved three main steps: coating the cellulose nonwoven fabric with copper via magnetron sputtering (CNW → CNW-Cu0), subsequent deposition with sodium alginate (CNW-Cu0 → CNW-Cu0/ALG-Na+), followed by cross-linking the alginate chains with calcium ions (CNW-Cu0/ALG-Na+ → CNW-Cu0/ALG-Ca2+). The primary objective of the work was to supply these composites with such biological attributes as antibacterial and hemostatic activity. Namely, equipping the antibacterial materials (copper action on representative Gram-positive and Gram-negative bacteria and fungal strains) with induction of blood plasma clotting processes (activated partial thromboplastin time (aPTT) and prothrombin time (PT)). We determined the effect of CNW-Cu0/ALG-Ca2+ materials on the viability of Peripheral blood mononuclear (PBM) cells. Moreover, we studied the interactions of CNW-Cu0/ALG-Ca2+ materials with DNA using the relaxation plasmid assay. However, results showed CNW-Cu0/ALG-Ca2+'s cytotoxic properties against PBM cells in a time-dependent manner. Furthermore, the CNW-Cu0/ALG-Ca2+ composite exhibited the potential to interact directly with DNA. The results demonstrated that the CNW-Cu0/ALG-Ca2+ composites synthesized show promising potential for wound dressing applications.

Synthesis and characterization of ion-induced sodium alginate/soy protein isolate microgels for the controlled release

In this study, sodium alginate/ soy protein isolate (SPI) microgels cross-linked by various divalent cations including Cu2+, Ba2+, Ca2+, and Zn2+ were fabricated. Cryo-scanning electron microscopy observations revealed distinctive structural variations among the microgels. In the context of gastric pH conditions, the degree of shrinkage of the microgels followed the sequence of Ca2+ > Ba2+ > Cu2+ > Zn2+. Meanwhile, under intestinal pH conditions, the degree of swelling was ranked as Zn2+ > Ca2+ > Ba2+ > Cu2+. The impact of these variations was investigated through in vitro digestion studies, revealing that all microgels successfully delayed the release of β-carotene within the stomach. Within the simulated intestinal fluid, the microgel cross-linked with Zn2+ exhibited an initial burst release, while those cross-linked with Cu2+, Ba2+, or Ca2+ displayed a sustained release pattern. This research underscores the potential of sodium alginate/SPI microgels cross-linked with different divalent cations as efficient controlled-release delivery systems.

Biodegradable Natural Hydrogels for Tissue Engineering, Controlled Release, and Soil Remediation

This article provides insights into hydrogels of the most promising biodegradable natural polymers and their mechanisms of degradation, highlighting the different possibilities of controlling hydrogel degradation rates. Since biodegradable hydrogels can be designed as scaffolding materials to mimic the physical and biochemical properties of natural tissues, these hydrogels have found widespread application in the field of tissue engineering and controlled release. In the same manner, their potential as water reservoirs, macro- and microelement carriers, or matrixes for the selective adsorption of pollutants make them excellent candidates for sustainable soil amendment solutions. Accordingly, this article summarizes the recent advances in natural biodegradable hydrogels in the fields of tissue engineering, controlled release, and soil remediation, emphasizing the new opportunities that degradability and its tunability offer for the design and applicability of hydrogels.

Genome Analysis of a Potential Novel Vibrio Species Secreting pH- and Thermo-Stable Alginate Lyase and Its Application in Producing Alginate Oligosaccharides

Alginate lyase is an attractive biocatalyst that can specifically degrade alginate to produce oligosaccharides, showing great potential for industrial and medicinal applications. Herein, an alginate-degrading strain HB236076 was isolated from Sargassum sp. in Qionghai, Hainan, China. The low 16S rRNA gene sequence identity (<98.4%), ANI value (<71.9%), and dDDH value (<23.9%) clearly indicated that the isolate represented a potential novel species of the genus Vibrio. The genome contained two chromosomes with lengths of 3,007,948 bp and 874,895 bp, respectively, totaling 3,882,843 bp with a G+C content of 46.5%. Among 3482 genes, 3332 protein-coding genes, 116 tRNA, and 34 rRNA sequences were predicted. Analysis of the amino acid sequences showed that the strain encoded 73 carbohydrate-active enzymes (CAZymes), predicting seven PL7 (Alg1-7) and two PL17 family (Alg8, 9) alginate lyases. The extracellular alginate lyase from strain HB236076 showed the maximum activity at 50 °C and pH 7.0, with over 90% activity measured in the range of 30-60 °C and pH 6.0-10.0, exhibiting a wide range of temperature and pH activities. The enzyme also remained at more than 90% of the original activity at a wide pH range (3.0-9.0) and temperature below 50 °C for more than 2 h, demonstrating significant thermal and pH stabilities. Fe2+ had a good promoting effect on the alginate lyase activity at 10 mM, increasing by 3.5 times. Thin layer chromatography (TLC) and electrospray ionization mass spectrometry (ESI-MS) analyses suggested that alginate lyase in fermentation broth could catalyze sodium alginate to produce disaccharides and trisaccharides, which showed antimicrobial activity against Shigella dysenteriae, Aeromonas hydrophila, Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli. This research provided extended insights into the production mechanism of alginate lyase from Vibrio sp. HB236076, which was beneficial for further application in the preparation of pH-stable and thermo-stable alginate lyase and alginate oligosaccharides.

Development of bio-based polymeric blends - a comprehensive review

The current impetus to develop bio-based polymers for greater sustainability and lower carbon footprint is necessitated due to the alarming depletion of fossil resources, concurrent global warming, and related environmental issues. This article reviews the development of polymeric blends based on bio-based polymers. The focus on bio-based polymers is due to their greater 'Sustainability factor' as they are derived from renewable resources. The article delves into the synthesis of both conventional and highly biodegradable bio-based polymers, each crafted from feedstocks derived from nature's bounty. What sets this work apart is the exploration of blending existing bio-based polymers, culminating in the birth of entirely new materials. This review provides a comprehensive overview of the recent advancements in the development of bio-based polymeric blends, covering their synthesis, properties, applications, and potential contributions to a more sustainable future. Despite their potential benefits, bio-based materials face obstacles such as miscibility, processability issues and disparities in physical properties compared to conventional counterparts. The paper also discusses significance of compatibilizers, additives and future directions for the further advancement of these bio-based blends. While bio-based polymer blends hold promise for environmentally benign applications, many are still in the research phase. Ongoing research and technological innovations are driving the evolution of these blends as viable alternatives, but continued efforts are needed to ensure their successful integration into mainstream industrial practices. Concerted efforts from both researchers and industry stakeholders are essential to realize the full potential of bio-based polymers and accelerate their adoption on a global scale.

A portable lateral flow distance-based paper sensor for drinking water hardness test

Hardness is one of the basic parameters of water, and a high-level hardness of drinking water may be harmful to human health. Thus, it is very important to monitor drinking water hardness. In this work, a portable lateral flow distance-based paper sensor for the semi-quantitative detection of drinking water hardness is demonstrated. In the presence of Ca2+/Mg2+, the hydrogel can be formed via the chelation between sodium alginate and Ca2+/Mg2+, inducing a phase separation process. The viscosity change of the sodium alginate solution is directly related to the Ca2+/Mg2+ concentration and can be determined by the water lateral flow distance on test strips. The sensor successfully realizes the quantification of Ca2+ and Mg2+ in the range of 0-10 mmol L-1 and 4-20 mmol L-1, respectively. The recoveries are found varied from 95% to 108.9%. The water hardness is acceptable for drinking if the Cr values lies in the range of 0.259 to 0.419, and it is high with the Cr value above 0.595. Remarkably, the performance of the sensor is comparable with the commercial kit for real water samples, which avoids the subjective judgment. Overall, this method provides a portable approach for semi-quantitative detection of drinking water hardness with the merits of convenience and low cost, which shows great potential for the potential application.

Alginate as a Sustainable and Biodegradable Material for Medical and Environmental Applications-The Case Studies

Alginates are salts of alginic acid derived mainly from sea algae of the genus brown algae. They are also synthesized by some bacteria. They belong to negatively charged polysaccharides exhibiting some rheological properties. High plasticity and the ability to modify the structure are the reasons for their application in numerous industries. Moreover, when in contact with the living tissue, they do not trigger an immune response, and for this reason they are the most often tested materials for medical applications. The paper discusses the latest applications, including 3D bioprinting, drug delivery systems, and sorptive properties. Recognizing alginates as biomaterials, it emphasizes the necessity for precise processing and modification to industrialize them for specific uses. This review aims to provide a thorough understanding of the advancements in alginate research, underscoring their potential for innovative applications.

Development and Comparative Evaluation of Imitated Fiber from Different Protein Sources Using Wet-Spinning

Texture is a major challenge in addressing the need to find sustainable meat alternatives, as consumers desire alternative meat to have a sensory profile like meat. In this study, the fabrication of imitated muscle fiber (IMF) is performed by introducing different kinds of protein sources, with an effective bottom-up technique- wet spinning. Herein, the protein sources (pea protein isolate, wheat protein, and myofibrillar paste) were combined with sodium alginate to stimulate the bonding with the coagulation solution for fabrication. It has been found that the fabrication of IMF is possible using all the protein sources, however, due to the difference in protein structure, a significant difference was observed in quality characteristics compared to conventional meat. Additionally, combination of wheat protein and pea protein isolate has given similar values as conventional meat in terms of some of the texture profiles and Warner-Bratzler shear force. In general, the optimization of protein sources for wet spinning can provides a novel way for the production of edible fiber of alternative meat.

Multifunctional Conductive Hydrogel Interface for Bioelectronic Recording and Stimulation

The past few decades have witnessed the rapid advancement and broad applications of flexible bioelectronics, in wearable and implantable electronics, brain-computer interfaces, neural science and technology, clinical diagnosis, treatment, etc. It is noteworthy that soft and elastic conductive hydrogels, owing to their multiple similarities with biological tissues in terms of mechanics, electronics, water-rich, and biological functions, have successfully bridged the gap between rigid electronics and soft biology. Multifunctional hydrogel bioelectronics, emerging as a new generation of promising material candidates, have authentically established highly compatible and reliable, high-quality bioelectronic interfaces, particularly in bioelectronic recording and stimulation. This review summarizes the material basis and design principles involved in constructing hydrogel bioelectronic interfaces, and systematically discusses the fundamental mechanism and unique advantages in bioelectrical interfacing with the biological surface. Furthermore, an overview of the state-of-the-art manufacturing strategies for hydrogel bioelectronic interfaces with enhanced biocompatibility and integration with the biological system is presented. This review finally exemplifies the unprecedented advancement and impetus toward bioelectronic recording and stimulation, especially in implantable and integrated hydrogel bioelectronic systems, and concludes with a perspective expectation for hydrogel bioelectronics in clinical and biomedical applications.

Action and cooperation in alginate degradation by three enzymes from the human gut bacterium Bacteroides eggerthii DSM 20697

Alginate is a polysaccharide consumed by humans in edible seaweed and different foods where it is applied as a texturizing hydrocolloid or in encapsulations of drugs and probiotics. While gut bacteria are found to utilize and ferment alginate to health-beneficial short-chain fatty acids, knowledge on the details of the molecular reactions is sparse. Alginates are composed of mannuronic acid (M) and its C-5 epimer guluronic acid (G). An alginate-related polysaccharide utilization locus (PUL) has been identified in the gut bacterium Bacteroides eggerthii DSM 20697. The PUL encodes two polysaccharide lyases (PLs) from the PL6 (BePL6) and PL17 (BePL17) families as well as a KdgF-like metalloprotein (BeKdgF) known to catalyze ring-opening of 4,5-unsaturated monouronates yielding 4-deoxy-l-erythro-5-hexoseulose uronate (DEH). B. eggerthii DSM 20697 does not grow on alginate, but readily proliferates with a lag phase of a few hours in the presence of an endo-acting alginate lyase A1-I from the marine bacterium Sphingomonas sp. A1. The B. eggerthii lyases are both exo-acting and while BePL6 is strictly G-block specific, BePL17 prefers M-blocks. BeKdgF retained 10-27% activity in the presence of 0.1-1 mM EDTA. X-ray crystallography was used to investigate the three-dimensional structure of BeKdgF, based on which a catalytic mechanism was proposed to involve Asp102, acting as acid/base having pKa of 5.9 as determined by NMR pH titration. BePL6 and BePL17 cooperate in alginate degradation with BeKdgF linearizing producing 4,5-unsaturated monouronates. Their efficiency of alginate degradation was much enhanced by the addition of the A1-I alginate lyase.

A macromolecular cross-linked alginate aerogel with excellent concentrating effect for rapid hemostasis

Alginate-based materials present promising potential for emergency hemostasis due to their excellent properties, such as procoagulant capability, biocompatibility, low immunogenicity, and cost-effectiveness. However, the inherent deficiencies in water solubility and mechanical strength pose a threat to hemostatic efficiency. Here, we innovatively developed a macromolecular cross-linked alginate aerogel based on norbornene- and thiol-functionalized alginates through a combined thiol-ene cross-linking/freeze-drying process. The resulting aerogel features an interconnected macroporous structure with remarkable water-uptake capacity (approximately 9000 % in weight ratio), contributing to efficient blood absorption, while the enhanced mechanical strength of the aerogel ensures stability and durability during the hemostatic process. Comprehensive hemostasis-relevant assays demonstrated that the aerogel possessed outstanding coagulation capability, which is attributed to the synergistic impacts on concentrating effect, platelet enrichment, and intrinsic coagulation pathway. Upon application to in vivo uncontrolled hemorrhage models of tail amputation and hepatic injury, the aerogel demonstrated significantly superior performance compared to commercial alginate hemostatic agent, yielding reductions in clotting time and blood loss of up to 80 % and 85 %, respectively. Collectively, our work illustrated that the alginate porous aerogel overcomes the deficiencies of alginate materials while exhibiting exceptional performance in hemorrhage, rendering it an appealing candidate for rapid hemostasis.

Alginate based hemostatic materials for bleeding management: A review

Severe bleeding has caused significant financial losses as well as a major risk to the lives and health of military and civilian populations. Under some situations, the natural coagulation mechanism of the body is unable to achieve fast hemostasis without the use of hemostatic drugs. Thus, the development of hemostatic materials and techniques is essential. Improving the quality of life and survival rate of patients and minimizing bodily damage requires fast, efficient hemostasis and prevention of bleeding. Alginate is regarded as an outstanding hemostatic polymer because of its non-immunogenicity, biodegradability, good biocompatibility, simple gelation, non-toxicity, and easy availability. This review summarizes the basics of hemostasis and emphasizes the recent developments regarding alginate-based hemostatic systems. Structural modifications and mixing with other materials have widely been used for the improvement of hemostatic characteristics of alginate and for making multifunctional medical devices that not only prevent uncontrolled bleeding but also have antibacterial characteristics, drug delivery abilities, and curing effects. This review is hoped to prepare critical insights into alginate modifications for better hemostatic properties.

Degradation of Polymer Films of Sodium Alginate during Prolonged Irradiation with X-ray under Ultra-High Vacuum

Sodium alginate (NaAlg) is widely used as a food additive. To study the effect of irradiation with X-ray quanta with energies of 1253.6 eV and 1486.6 eV on the composition of NaAlg, thick films with a smooth surface were prepared, which did not differ in IR spectra from the original powders. The films were irradiated in a high vacuum (3 × 10-10 mbar) in the chamber of a Specs PHOIBOS 150 MCD9 XPS spectrometer with an X-ray source power of 150 W and an irradiation duration of up to 300 min, which significantly exceeded the time required to obtain an XPS spectrum. This made it possible to use XPS to monitor changes in the composition of the NaAlg surface directly during irradiation. As a result of the research, it has been established that NaAlg degrades with prolonged irradiation, which is accompanied by a significant decrease in the O/C ratio. When analyzing the dependence of the intensities of individual peaks in the C1s spectrum on the irradiation time, it was found that after 100 min of irradiation, a peak due to the carbonate group appears in the spectrum. The decomposition was also accompanied by a change in the color of NaAlg from white to yellow-brown. In the IR spectrum of the NaAlg film irradiated for 300 min, an absorption band was detected at 1910 cm-1, which is usually associated with the presence of allene groups.

Recent Advances in Hydrogel-Based 3D Bioprinting and Its Potential Application in the Treatment of Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, requiring invasive surgery often before a child's first birthday. Current materials used during CHD surgery lack the ability to grow, remodel, and regenerate. To solve those limitations, 3D bioprinting is an emerging tool with the capability to create tailored constructs based on patients' own imaging data with the ability to grow and remodel once implanted in children with CHD. It has the potential to integrate multiple bioinks with several cell types and biomolecules within 3D-bioprinted constructs that exhibit good structural fidelity, stability, and mechanical integrity. This review gives an overview of CHD and recent advancements in 3D bioprinting technologies with potential use in the treatment of CHD. Moreover, the selection of appropriate biomaterials based on their chemical, physical, and biological properties that are further manipulated to suit their application are also discussed. An introduction to bioink formulations composed of various biomaterials with emphasis on multiple cell types and biomolecules is briefly overviewed. Vasculogenesis and angiogenesis of prefabricated 3D-bioprinted structures and novel 4D printing technology are also summarized. Finally, we discuss several restrictions and our perspective on future directions in 3D bioprinting technologies in the treatment of CHD.

Hydrogels Based on Proteins Cross-Linked with Carbonyl Derivatives of Polysaccharides, with Biomedical Applications

Adding carbonyl groups into the hydrogel matrix improves the stability and biocompatibility of the hydrogels, making them suitable for different biomedical applications. In this review article, we will discuss the use of hydrogels based on polysaccharides modified by oxidation, with particular attention paid to the introduction of carbonyl groups. These hydrogels have been developed for several applications in tissue engineering, drug delivery, and wound healing. The review article discusses the mechanism by which oxidized polysaccharides can introduce carbonyl groups, leading to the development of hydrogels through cross-linking with proteins. These hydrogels have tunable mechanical properties and improved biocompatibility. Hydrogels have dynamic properties that make them promising biomaterials for various biomedical applications. This paper comprehensively analyzes hydrogels based on cross-linked proteins with carbonyl groups derived from oxidized polysaccharides, including microparticles, nanoparticles, and films. The applications of these hydrogels in tissue engineering, drug delivery, and wound healing are also discussed.

Fabrication and Biomedical Application of Alginate Composite Hydrogels in Bone Tissue Engineering: A Review

Nowadays, as a result of the frequent occurrence of accidental injuries and traumas such as bone damage, the number of people causing bone injuries or fractures is increasing around the world. The design and fabrication of ideal bone tissue engineering (BTE) materials have become a research hotspot in the scientific community, and thus provide a novel path for the treatment of bone diseases. Among the materials used to construct scaffolds in BTE, including metals, bioceramics, bioglasses, biomacromolecules, synthetic organic polymers, etc., natural biopolymers have more advantages against them because they can interact with cells well, causing natural polymers to be widely studied and applied in the field of BTE. In particular, alginate has the advantages of excellent biocompatibility, good biodegradability, non-immunogenicity, non-toxicity, wide sources, low price, and easy gelation, enabling itself to be widely used as a biomaterial. However, pure alginate hydrogel as a BTE scaffold material still has many shortcomings, such as insufficient mechanical properties, easy disintegration of materials in physiological environments, and lack of cell-specific recognition sites, which severely limits its clinical application in BTE. In order to overcome the defects of single alginate hydrogels, researchers prepared alginate composite hydrogels by adding one or more materials to the alginate matrix in a certain proportion to improve their bioapplicability. For this reason, this review will introduce in detail the methods for constructing alginate composite hydrogels, including alginate/polymer composite hydrogels, alginate/bioprotein or polypeptide composite hydrogels, alginate/bioceramic composite hydrogels, alginate/bioceramic composite hydrogels, and alginate/nanoclay composite hydrogels, as well as their biological application trends in BTE scaffold materials, and look forward to their future research direction. These alginate composite hydrogel scaffolds exhibit both unexceptionable mechanical and biochemical properties, which exhibit their high application value in bone tissue repair and regeneration, thus providing a theoretical basis for the development and sustainable application of alginate-based functional biomedical materials.

Effects of alginate synergized with polyphenol compounds on the retrogradation properties of corn starch

This study aimed to investigate the impact of alginate (AG) on the retrogradation properties of corn starch (CS) in conjunction with three phenolic compounds, including naringin (NA), rutin (RT), and soy isoflavones (SI). The findings indicated that AG, NA, RT, and SI collectively resulted in a significant reduction in the hardness, retrogradation enthalpy, and relaxation time of CS gel. This effect was more pronounced when compared to NA, RT, and SI individually. The findings suggested that the elemental system comprising AG, phenolic compounds, and CS yielded enhanced water retention capacity and thermal stability. Moreover, a noticeable decrease in the short-range ordered structure and crystallinity was observed, indicating that AG and phenolic compounds effectively inhibited the retrogradation of CS; notably, the synergistic interaction between AG and SI resulted in the most favorable outcome. The results of this study provide new ideas for the design, development, and quality improvement of starch-based food.

Nanomaterials for diabetes: diagnosis, detection and delivery

537 million people worldwide suffer from diabetes mellitus, a problem of glucose management that is related to a number of major health risks, including cardiovascular diseases. There is a need for new, efficient formulations of diabetic medications to address this condition and its related consequences because existing treatments have a number of drawbacks and limits. This encouraged the development of treatment plans to get around some of these restrictions, like low therapeutic drug bioavailability or patients' disobedience to existing therapies. Approaches based on nanotechnology have a lot of promise to enhance the treatment of diabetic patients. In order to manage blood glucose, this review article highlights recent developments and explores the potential applications of different materials (polymeric, ceramic, dendrimers, etc.) as nanocarriers for the delivery of insulin and other antidiabetic medications. Using an injectable and acid-degradable polymeric network produced by the electrostatic interaction of oppositely charged dextran nanoparticles loaded with insulin and glucose-specific enzymes, we reviewed a glucose-mediated release approach for the self-regulated delivery of insulin, in which, after a degradable nano-network was subcutaneously injected into type 1 diabetic mice,in vivoexperiments confirmed that these formulations improved glucose management. In addition, a discussion of silica-based nanocarriers, their potential for treating diabetes and controlling blood glucose levels, and an explanation of the role of dendrimers in diabetes treatment have been covered. This is done by utilizing the properties of silica nanoparticles, such as their tuneable particle and pore size, surface chemistry, and biocompatibility. The article summarized the significance of nanomaterials and their uses in the diagnosis and treatment of diabetes overall, illuminating the field's potential and outlining its prospects for the future.

Alginate-Based Electrospun Nanofibers and the Enabled Drug Controlled Release Profiles: A Review

Alginate is a natural polymer with good biocompatible properties and is a potential polymeric material for the sustainable development and replacement of petroleum derivatives. However, the non-spinnability of pure alginate solutions has hindered the expansion of alginate applications. With the continuous development of electrospinning technology, synthetic polymers, such as PEO and PVA, are used as co-spinning agents to increase the spinnability of alginate. Moreover, the coaxial, parallel Janus, tertiary and other diverse and novel electrospun fiber structures prepared by multi-fluid electrospinning have found a new breakthrough for the problem of poor spinning of natural polymers. Meanwhile, the diverse electrospun fiber structures effectively achieve multiple release modes of drugs. The powerful combination of alginate and electrostatic spinning is widely used in many biomedical fields, such as tissue engineering, regenerative engineering, bioscaffolds, and drug delivery, and the research fever continues to climb. This is particularly true for the controlled delivery aspect of drugs. This review provides a brief overview of alginate, introduces new advances in electrostatic spinning, and highlights the research progress of alginate-based electrospun nanofibers in achieving various controlled release modes, such as pulsed release, sustained release, biphasic release, responsive release, and targeted release.

Functional hydrogels for hepatocellular carcinoma: therapy, imaging, and in vitro model

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide and is characterized by high rates of morbidity and mortality, posing a serious threat to human health. Interventional embolization therapy is the main treatment against middle- and late-stage liver cancer, but its efficacy is limited by the performance of embolism, hence the new embolic materials have provided hope to the inoperable patients. Especially, hydrogel materials with high embolization strength, appropriate viscosity, reliable security and multifunctionality are widely used as embolic materials, and can improve the efficacy of interventional therapy. In this review, we have described the status of research on hydrogels and challenges in the field of HCC therapy. First, various preparation methods of hydrogels through different cross-linking methods are introduced, then the functions of hydrogels related to HCC are summarized, including different HCC therapies, various imaging techniques, in vitro 3D models, and the shortcomings and prospects of the proposed applications are discussed in relation to HCC. We hope that this review is informative for readers interested in multifunctional hydrogels and will help researchers develop more novel embolic materials for interventional therapy of HCC.

Chemically modified seaweed polysaccharides: Improved functional and biological properties and prospective in food applications

Seaweed polysaccharides are natural biomacromolecules with unique physicochemical properties (e.g., good gelling, emulsifying, and film-forming properties) and diverse biological activities (e.g., anticoagulant, antioxidant, immunoregulatory, and antitumor effects). Furthermore, they are nontoxic, biocompatible and biodegradable, and abundant in resources. Therefore, they have been widely utilized in food, cosmetics, and pharmaceutical industries. However, their properties and bioactivities sometimes are not satisfactory for some purposes. Modification of polysaccharides can impart the amphiphilicity and new functions to the biopolymers and change the structure and conformation, thus effectively improving their functional properties and biological activities so as to meet the requirement for targeted applications. This review outlined the modification methods of representative red algae polysaccharides (carrageenan and agar), brown algae polysaccharides (fucoidan, alginate, and laminaran), and green algae polysaccharides (ulvan) that have potential food applications, including etherification, esterification, degradation, sulfation, phosphorylation, selenylation, and so on. The improved functional properties and bioactivities of the modified seaweed polysaccharides and their potential food applications are also summarized.

Integration of Electrospun Scaffolds and Biological Polymers for Enhancing the Delivery and Efficacy of Mesenchymal Stem/Stromal Cell Therapies

Mesenchymal stem/stromal cells (MSCs) have emerged as a promising therapeutic approach for a variety of diseases due to their immunomodulatory and tissue regeneration capabilities. Despite their potential, the clinical application of MSC therapies is hindered by limited cell retention and engraftment at the target sites. Electrospun scaffolds, with their high surface area-to-volume ratio and tunable physicochemical properties, can be used as platforms for MSC delivery. However, synthetic polymers often lack the bioactive cues necessary for optimal cell-scaffold interactions. Integrating electrospun scaffolds and biological polymers, such as polysaccharides, proteins, and composites, combines the mechanical integrity of synthetic materials with the bioactivity of natural polymers and represents a strategic approach to enhance cell-scaffold interactions. The molecular interactions between MSCs and blended or functionalized scaffolds have been examined in recent studies, and it has been shown that integration can enhance MSC adhesion, proliferation, and paracrine secretion through the activation of multiple signaling pathways, such as FAK/Src, MAPK, PI3K/Akt, Wnt/β-catenin, and YAP/TAZ. Preclinical studies on small animals also reveal that the integration of electrospun scaffolds and natural polymers represents a promising approach to enhancing the delivery and efficacy of MSCs in the context of regenerating bone, cartilage, muscle, cardiac, vascular, and nervous tissues. Future research should concentrate on identifying the distinct characteristics of the MSC niche, investigating the processes involved in MSC-scaffold interactions, and applying new technologies in stem cell treatment and biofabrication to enhance scaffold design. Research on large animal models and collaboration among materials scientists, engineers, and physicians are crucial to translating these advancements into clinical use.

Material-specific binding peptides empower sustainable innovations in plant health, biocatalysis, medicine and microplastic quantification

Material-binding peptides (MBPs) have emerged as a diverse and innovation-enabling class of peptides in applications such as plant-/human health, immobilization of catalysts, bioactive coatings, accelerated polymer degradation and analytics for micro-/nanoplastics quantification. Progress has been fuelled by recent advancements in protein engineering methodologies and advances in computational and analytical methodologies, which allow the design of, for instance, material-specific MBPs with fine-tuned binding strength for numerous demands in material science applications. A genetic or chemical conjugation of second (biological, chemical or physical property-changing) functionality to MBPs empowers the design of advanced (hybrid) materials, bioactive coatings and analytical tools. In this review, we provide a comprehensive overview comprising naturally occurring MBPs and their function in nature, binding properties of short man-made MBPs (<20 amino acids) mainly obtained from phage-display libraries, and medium-sized binding peptides (20-100 amino acids) that have been reported to bind to metals, polymers or other industrially produced materials. The goal of this review is to provide an in-depth understanding of molecular interactions between materials and material-specific binding peptides, and thereby empower the use of MBPs in material science applications. Protein engineering methodologies and selected examples to tailor MBPs toward applications in agriculture with a focus on plant health, biocatalysis, medicine and environmental monitoring serve as examples of the transformative power of MBPs for various industrial applications. An emphasis will be given to MBPs' role in detecting and quantifying microplastics in high throughput, distinguishing microplastics from other environmental particles, and thereby assisting to close an analytical gap in food safety and monitoring of environmental plastic pollution. In essence, this review aims to provide an overview among researchers from diverse disciplines in respect to material-(specific) binding of MBPs, protein engineering methodologies to tailor their properties to application demands, re-engineering for material science applications using MBPs, and thereby inspire researchers to employ MBPs in their research.