Recent Development of Alginate-Based Materials and Their Versatile Functions in Biomedicine, Flexible Electronics, and Environmental Uses

Advances in green carbon-based biosorbents: From conventional to miniaturized sample preparation strategies

Developing novel sorbent phases has advanced solid-based sample preparation techniques, improving analytical performance in complex matrices. Carbon-based sorbents, known for their high surface area, thermal and mechanical stability, and modifiability due to abundant organic functional groups, have emerged as exceptional materials in this field. Due to their versatile characteristics, carbon-based materials have been extensively investigated as promising materials for anchoring and functionalization with biopolymers, resulting in innovative hybrid materials, so-called carbon-based biosorbents. These biosorbents offer numerous advantages, including enhanced physicochemical properties and biodegradability, which help reduce the environmental impact of their synthesis, particularly when compared to conventional synthetic sorbent production methods that lack adherence to environmentally sustainable protocols. Among the various biopolymers used for modification, chitosan, starch, cyclodextrin, cellulose, and agarose have been identified as promising candidates for integration with carbon-based materials. In light of the ongoing advancements in developing novel carbon-based biosorbent materials, this review aims to highlight their synthesis using these biopolymers and examine their application in conventional and miniaturized sample preparation techniques across diverse matrices.

Fluorescent alginate fiber with super-strong and super-tough mechanical performances for biomedical applications

Emerging research attentions are focused on the development of fluorescent biomaterials for various biomedical applications, including fluorescence-guided surgery. However, it is still challenging to prepare biomolecules-based fluorescent fibers with both satisfactory biocompatibility and optimal mechanical properties. Here, we develop a fluorescent robust biofiber through using a tetraphenylethene-containing surfactant as the contact points between polysaccharide chains of alginate. This newly developed contact points not only strengthen the cross-linking network of polysaccharide chains, but also afford enough energy-dissipating slippage for polysaccharide chains. Consequently, the generated fluorescent fiber is endowed with highly improved mechanical performances from plastic strain stage. The experimental results indicate that the fluorescent fiber shows good mechanical properties of breaking strength of 1.10 GPa (12.09 cN/dtex), Young's modulus of 39.81 GPa and toughness of 137.26 MJ/m3, which are comparable to those of dragline silk and outperforming spider silk proteins and other artificial materials. More importantly, its satisfactory biosafety and wound healing-promoting ability as a fluorescent suture are solidly proved by both in vitro and in vivo assays, which opens an opportunity for its biological and biomedical applications. This study provides a novel strategy for the development of robust fluorescent biomaterials.

Electroconductive Nanocellulose, a Versatile Hydrogel Platform: From Preparation to Biomedical Engineering Applications

Nanocelluloses have garnered significant attention recently in the attempt to create sustainable, improved functional materials. Nanocellulose possesses wide varieties, including rod-shaped crystalline cellulose nanocrystals and elongated cellulose nanofibers, also known as microfibrillated cellulose. In recent times, nanocellulose has sparked research into a wide range of biomedical applications, which vary from developing 3D printed hydrogel to preparing structures with tunable characteristics. Owing to its multifunctional properties, different categories of nanocellulose, such as cellulose nanocrystals, cellulose nanofibers, and bacterial nanocellulose, as well as their unique properties are discussed here. Here, different methods of nanocellulose-based hydrogel preparation are covered, which include 3D printing and crosslinking methods. Subsequently, advanced nanocellulose-hydrogels addressing conductivity, shape memory, adhesion, and structural color are highlighted. Finally, the application of nanocellulose-based hydrogel in biomedical applications is explored here. In summary, numerous perspectives on novel approaches based on nanocellulose-based research are presented here.

Super-Strong, Super-Stiff, and Super-Tough Fluorescent Alginate Fibers with Outstanding Tolerance to Extreme Conditions

The combination of multiple physical properties is of great importance for widening the application scenarios of biomaterials. It remains a great challenge to fabricate biomolecules-based fibers gaining both mechanical strength and toughness which are comparable to natural spider dragline silks. Here, by mimicking the structure of dragline silks, a high-performance fluorescent fiber Alg-TPEA-PEG is designed by non-covalently cross-linking the polysaccharide chains of alginate with AIEgen-based surfactant molecules as the flexible contact points. The non-covalent cross-linking network provides sufficient energy-dissipating slippage between polysaccharide chains, leading to Alg-TPEA-PEG with highly improved mechanical performances from the plastic strain stage. By successfully transferring the extraordinary mechanical performances of polysaccharide chains to macroscopic fibers, Alg-TPEA-PEG exhibits an outstanding breaking strength of 1.27 GPa, Young's modulus of 34.13 GPa, and toughness of 150.48 MJ m-3, which are comparable to those of dragline silk and outperforming other artificial materials. More importantly, both fluorescent and mechanical properties of Alg-TPEA-PEG can be well preserved under various harsh conditions, and the fluorescence and biocompatibility facilitate its biological and biomedical applications. This study affords a new biomimetic designing strategy for gaining super-strong, super-stiff, and super-tough fluorescent biomaterials.

The development of functionalized alginate-based hydrogels for the management of postprandial hyperglycemia and weight reduction

Polysaccharide-derived functional food ingredients are increasingly prevalent in the food industry for their health benefits and functional versatility. Among them, sodium alginate (SA), a natural polysaccharide, is widely valued for its sustainability, renewability, non-toxic nature, and broad applicability. However, its poor water solubility has limited its use as biomedical materials and food additives. Here, we enhanced SA through carboxymethylation to produce carboxymethylated SA (CMSA), aiming to develop functional food ingredients with improved physicochemical properties for health management. The synthesized CMSA was characterized for its physical properties and ability to form a hydrogel through cross-linking with Ca2+. We assessed its encapsulation efficiency for food particles in simulated gastric and intestinal fluids and evaluated its physiological effects in a rat model. Our findings demonstrated that CMSA-based hydrogels effectively encapsulate ingredients in the stomach, reducing nutrient diffusion in the intestine, and helping to manage postprandial hypoglycemia. Additionally, the hydrogel expands in the stomach and small intestine, contributing to modest weight loss. These findings suggest that CMSA-based hydrogels offer significant potential as functional food ingredients for managing postprandial hypoglycemia and supporting weight management. The development of such gelling systems presents promising applications in both medical and nutritional sciences, offering innovative strategies for addressing diet-related health concerns.

Natural biopolymers in the fabrication and coating of ureteral stent: An overview

Ureteral stents are indwelling medical devices that are most commonly used in treating different urinary tract complications like ureteral obstruction, kidney stones, and strictures, and allow normal urine flow from the kidney to the bladder. Tremendous work has been done in ureteral stent technology to meet the clinical demands, however, till-date a gold standard material for ureteral stents has not yet been developed. Many materials such as metal, and synthetic polymers have been published, however, the role of natural biopolymers has not yet been summarized and discussed. There is no detailed review published to explain the role of natural biopolymers in ureteral stent technology. This is the first review that explains and summarizes the role of natural polymer in ureter stent technology. In this review alginate and chitosan polymers are discussed in detail in the fabrications and coating of ureteral stents. It was summarized that alginate polymer alone or in combination with other polymers have been successfully used by many researchers for the manufacturing of ureteral stents with satisfactory results in vitro, in vivo, and clinical trials. However, alginate is rarely used to coat the surface of ureteral stent. On the other hand, only two reports are available on chitosan polymers for the manufacturing of ureteral stents, however, chitosan is largely used to coat the existing ureteral stents owing to their good antibacterial characteristics. Coating procedures can inhibit encrustation and biofilm formation. Nevertheless, the lack of antibacterial efficiency and inadequate coating limit their applications, however, natural biopolymers like chitosan showed significant promises in coating. Overall, the renewable nature, abundant, biocompatible, and biodegradable potential of natural polymer can be established with significant aspects as the ideal ureteral stent. To fully utilize the potential of the natural biopolymers in the ureteral stent design or coatings, an in-depth study is required to understand and identify their performance both in vitro and in vivo in the urinary tract.

Algae-Derived Nacre-like Dielectric Bionanocomposite with High Loading Hexagonal Boron Nitride for Green Electronics

The surging demand for electronics is causing detrimental environmental consequences through massive electronic waste production. Urgently shifting toward renewable and eco-friendly materials is crucial for fostering a green circular economy. Herein, we develop a multifunctional bionanocomposite using an algae-derived carbohydrate biopolymer (alginate) and boron nitride nanosheet (BNNS) that can be readily employed as a multifunctional dielectric material. The adopted rational design principle includes spatial locking of superhigh loading of BNNS via hydrogel casting followed by layer-by-layer assembly via solvent evaporation, successive cross-link engineering, and hot pressing. We harness the hierarchical assembly of BNNS and the molecular interaction of alginates with BNNS to achieve synergistic material properties with excellent mechanical robustness (tensile strength ∼135 MPa, Young's modulus ∼18 GPa), flexibility, thermal conductivity (∼4.5 W m-1 K-1), flame retardance, and dielectric properties (dielectric constant ∼7, dielectric strength ∼400 V/μm, and maximum energy density ∼4.33 J/cm3) that outperform traditional synthetic polymer dielectrics. Finally, we leverage the synergistic material properties of our engineered bionanocomposite to showcase its potential in green electronic applications, for example, supercapacitors and flexible interconnects. The supercapacitor device consisting of aerosol jet-printed single-walled carbon nanotube electrodes on our engineered bionanocomposite demonstrated a volumetric capacitance of ∼7 F/cm3 and robust rate capability, while the printed silver interconnects maintained conductivity in various deformed states (i.e., bending or flexing).

3D printed biopolymer/black phosphorus nanoscaffolds for bone implants: A review

Bone implantation is one of the recognized and effective means of treating bone defects, but osteoporosis and bone tumor-related bone abnormalities have a series of problems such as susceptibility to infection, difficulty in healing, and poor therapeutic effect, which poses a great challenge to clinical medicine. Three-dimensional things may be printed using 3D printing. Researchers can feed materials through the printer layer by layer to create the desired shape for a 3D structure. It is widely employed in the healing of bone defects, and it is an improved form of additive manufacturing technology with prospective future applications. This review's objective is to provide an overview of the findings reports pertaining to 3D printing biopolymers in recent years, provide an overview of biopolymer materials and their composites with black phosphorus for 3D printing bone implants, and the characterization methods of composite materials are also summarized. In addition, summarizes 3D printing methods based on ink printing and laser printing, pointing out their special features and advantages, and provide a combination strategy of photothermal therapy and bone regeneration materials for black phosphorus-based materials. Finally, the associations between bone implant materials and immune cells, the bio-environment, as well as the 3D printing bone implants prospects are outlined.

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.

Supramolecular Interfacial Assembly: Integrating Supramolecular Hosts into Polymeric Membranes through an Aqueous Interface

Efficient incorporation of macrocycles in polymeric membranes can impart the overall matrix with new properties for a range of cutting-edge applications. Here, we introduce a Supramolecular Interfacial Assembly (SIA) method for the fabrication of polymeric membranes featuring embedded macrocycles. Through harnessing the quasi-liquid nature of the concentrated polymer solution, SIA orchestrates the homogeneous spreading of macrocycles in an aqueous layer on its surface, leading to the creation of an interface between "water/water" phases, subsequently forming a cross-linked membrane driven by supramolecular electrostatic interactions. Remarkably, compared to the traditional interfacial polymerization, SIA adheres to a "green" paradigm without the need for organic solvents. The resultant composite membrane exhibits superior performance in organic solvent nanofiltration (OSN), owing to the precise molecular sieving property provided by the macrocycles with well-defined permanent cavities. This fabrication method holds great promise for the innovative design and production of composite membranes that seamlessly integrates macrocycles with conventional polymers, which can greatly impact the design and preparation of advanced membrane materials in the future.

Multi-Colored Aqueous Ink for Rewritable Paper

As sustainable and eco-friendly replacements to conventional paper, rewritable paper is a very attractive alternative for communication, information circulation, and storage. Development is made for rewritable paper using chromogenic materials that change its color in presence of external stimuli. However, the new techniques have faced several major challenges including feasible operational method, eco-friendly approach. Herein, a simple, convenient, and eco-friendly strategy is described for the preparation of rewritable paper substrate, and multi colored ink for efficient use in writing, painting or printing purpose. In addition, writing with "invisible ink" on the rewritable paper can be realized for potential anti-counterfeiting application. The written, painted, or printed information on the paper substrate can be easily erased using an aqueous solution. Thus, the original paper can be retrieved and the paper substrate can be reused multiple times. Besides, the written or printed information can be retained for a prolonged time at ambient conditions. Overall, this approach shows the rewritable paper as a prototype of multicolor writing/painting application, offering a sustainable solution for reducing paper waste and promoting environmental stewardship.

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.

Preparation of bright yellow color sodium alginate solution

Sodium alginate (SA) is a marine polysaccharide biomass material that is environmentally friendly and exhibits color-changing properties under certain conditions. In this study, we have discovered sodium alginate solution to be chromogenic under four conditions, namely alkali-chromogenic, thermo-chromogenic, force-chromogenic and photo-chromogenic. Under simple strong alkaline conditions, sodium alginate forms clusters of blue light-absorbing chromogenic aggregates, which exhibit a bright yellow color at a certain size. Under different temperature conditions, SA shows varying shades of yellow, and the color tends to stabilize after 48 h of resting. The aggregates can be dispersed by stirring, which changes SA from yellow to colorless. The yellow color can then be recovered after resting. Additionally, exposure to sunlight can cause the yellow SA to fade, but the color can be restored by reheating. Therefore, the force-chromogenic and photo-chromogenic properties are reversible. This makes it a promising material for use in color-developing and indicating materials. It is expected to become a sodium alginate cluster pigment with broad application prospects in the future.

Comprehensive Assessment of Collagen/Sodium Alginate-Based Sponges as Hemostatic Dressings

In our search for a biocompatible composite hemostatic dressing, we focused on the design of a novel biomaterial composed of two natural biological components, collagen and sodium alginate (SA), cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) and oxidized sodium alginate (OSA). We conducted a series of tests to evaluate the physicochemical properties, acute systemic toxicity, skin irritation, intradermal reaction, sensitization, cytotoxicity, and in vivo femoral artery hemorrhage model. The results demonstrated the excellent biocompatibility of the collagen/sodium alginate (C/SA)-based dressings before and after crosslinking. Specifically, the femoral artery hemorrhage model revealed a significantly shortened hemostasis time of 132.5 ± 12.82 s for the EDC/NHS cross-linked dressings compared to the gauze in the blank group (hemostasis time of 251.43 ± 10.69 s). These findings indicated that C/SA-based dressings exhibited both good biocompatibility and a significant hemostatic effect, making them suitable for biomedical applications.

A Degradable Tribotronic Transistor for Self-Destructing Intelligent Package e-Labels

Recently, discarded electronic products have caused serious environmental pollution and information security issues, which have attracted widespread attention. Here, a degradable tribotronic transistor (DTT) for self-destructing intelligent package e-labels has been developed, integrated by a triboelectric nanogenerator and a protonic field-effect transistor with sodium alginate as a dielectric layer. The triboelectric potential generated by external contact electrification is used as the gate voltage of the organic field-effect transistor, which regulates carrier transport through proton migration/accumulation. The DTT has successfully demonstrated its output characteristics with a high sensitivity of 0.336 mm-1 and a resolution of over 100 μm. Moreover, the DTT can be dissolved in water within 3 min and completely degraded in soil within 12 days, demonstrating its excellent degradation characteristics, which may contribute to environmental protection. Finally, an intelligent package e-label based on the modulation of the DTT is demonstrated, which can display information about the package by a human touch. The e-label will automatically fail due to the degradation of the DTT over time, achieving the purpose of information confidentiality. This work has not only presented a degradable tribotronic transistor for package e-labels but also exhibited bright prospects in military security, information hiding, logistics privacy, and personal affairs.

Recent advancements in bio-based dielectric and piezoelectric polymers and their biomedical applications

The advent of polymer-based dielectrics marked a significant breakthrough in dielectric materials. However, despite their many advantages, they pose serious environmental threats. Therefore, in recent years, there has been growing interest in bio-based polymers as a sustainable alternative to traditional petroleum-based polymers. Their renewable nature and reduced environmental impact can fulfil the rising demand for eco-friendly substitutes. Beyond their ecological benefits, bio-based polymers also possess distinctive electrical properties that make them extremely attractive in a variety of applications. Considering these, herein, we present recent advancements in bio-based dielectric polymers and nanocomposites. First, the fundamental concepts of dielectric and polymer-based dielectric materials are covered. Then, we will delve into the discussion of recent advancements in the dielectric properties and thermal stability of bio-based polymers, including polylactic acid, polyhydroxyalkanoates, polybutylene succinate, starch, cellulose, chitosan, chitins, and alginates, and their nanocomposites. Other novel bio-based dielectric polymers and their distinct dielectric characteristics have also been pointed out. In an additional section, the piezoelectric properties of these polymers and their recent biomedical applications have been highlighted and discussed thoroughly. In conclusion, this paper thoroughly discusses the recent advances in bio-based dielectric polymers and their potential to revolutionize the biomedical industry while cultivating a more sustainable and greener future.

Interpenetrating gelatin/alginate mixed hydrogel: The simplest method to prepare an autoclavable scaffold

The choice of sterilization method for hydrogels used for cell culture influences the ease of preparing the gel. We prepared interpenetrating gelatin/calcium alginate hydrogels containing 1% (w/v) alginate and 1-16% (w/v) gelatin by molding with the mixture of gelatin/sodium alginate solution, followed by the addition of calcium ions by incubation in calcium chloride solution. It is the simplest method to prepare autoclavable gelatin/sodium hydrogel. We measured various properties of the hydrogels including volume, Young's modulus in the compression test, storage modulus, and loss modulus in the dynamic viscoelasticity measurement. The gelatin/alginate hydrogel can be easily fabricated into any shape by this method. After autoclave treatment, the hydrogel was shrunk to smaller than the original shape in similar figures. The shape of the gelatin/alginate hydrogel can be designed into any shape with the reduction ratio of the volume. Human osteosarcoma (HOS) cells adhered to the gelatin/alginate hydrogel and then proliferated. Gelatin/calcium alginate hydrogels with a high concentration are considered to be autoclavable culture substrates because of their low deformation and gelatin elution rate after autoclaving and the high amount of cells attached to the hydrogels.

Building respirable powder architectures: utilizing polysaccharides for precise control of particle morphology for enhanced pulmonary drug delivery

INTRODUCTION

Dry powder inhaler (DPI) formulations are gaining attention as universal formulations with applications in a diverse range of drug formulations. The practical application of DPIs to pulmonary drugs requires enhancing their delivery efficiency to the target sites for various treatment modalities. Previous reviews have not explored the relation between particle morphology and delivery to different pulmonary regions. This review introduces new approaches to improve targeted DPI delivery using novel particle design such as supraparticles and metal-organic frameworks based on cyclodextrin.

AREAS COVERED

This review focuses on the design of DPI formulations using polysaccharides, promising excipients not yet approved by regulatory agencies. These excipients can be used to design various particle morphologies by controlling their physicochemical properties and manufacturing methods.

EXPERT OPINION

Challenges associated with DPI formulations include poor access to the lungs and low delivery efficiency to target sites in the lung. The restricted applicability of typical excipients contributes to their limited use. However, new formulations based on polysaccharides are expected to establish a technological foundation for the development of DPIs capable of delivering modalities specific to different lung target sites, thereby enhancing drug delivery.

Recent Progress of Anti-Freezing, Anti-Drying, and Anti-Swelling Conductive Hydrogels and Their Applications

Hydrogels are soft-wet materials with a hydrophilic three-dimensional network structure offering controllable stretchability, conductivity, and biocompatibility. However, traditional conductive hydrogels only operate in mild environments and exhibit poor environmental tolerance due to their high water content and hydrophilic network, which result in undesirable swelling, susceptibility to freezing at sub-zero temperatures, and structural dehydration through evaporation. The application range of conductive hydrogels is significantly restricted by these limitations. Therefore, developing environmentally tolerant conductive hydrogels (ETCHs) is crucial to increasing the application scope of these materials. In this review, we summarize recent strategies for designing multifunctional conductive hydrogels that possess anti-freezing, anti-drying, and anti-swelling properties. Furthermore, we briefly introduce some of the applications of ETCHs, including wearable sensors, bioelectrodes, soft robots, and wound dressings. The current development status of different types of ETCHs and their limitations are analyzed to further discuss future research directions and development prospects.

The Controlled Release of Abscisic Acid (ABA) Utilizing Alginate-Chitosan Gel Blends: A Synergistic Approach for an Enhanced Small-Molecule Delivery Controller

The integration of abscisic acid (ABA) into a chitosan-alginate gel blend unveils crucial insights into the formation and stability of these two substances. ABA, a key phytohormone in plant growth and stress responses, is strategically targeted for controlled release within these complexes. This study investigates the design and characterization of this novel controlled-release system, showcasing the potential of alginate-chitosan gel blends in ABA delivery. Computational methods, including molecular dynamics simulations, are employed to analyze the structural effects of microencapsulation, offering valuable insights into complex behavior under varying conditions. This paper focuses on the controlled release of ABA from these complexes, highlighting its strategic importance in drug delivery systems and beyond. This controlled release enables targeted and regulated ABA delivery, with far-reaching implications for pharmaceuticals, agriculture, and plant stress response studies. While acknowledging context dependency, the paper suggests that the liberation or controlled release of ABA holds promise in applications, urging further research and experimentation to validate its utility across diverse fields. Overall, this work significantly contributes to understanding the characteristics and potential applications of chitosan-alginate complexes, marking a noteworthy advancement in the field of controlled-release systems.

A multiscale approach to assess thermomechanical performance and force generation in nanorobotic microgels

We present a multiscale approach to characterize the performance of photothermally powered, nanorobotic 3D microgels. Optically triggered nanoactuators, consisting of a gold nanorod core and thermoresponsive pNIPMAM shell, are used as building blocks to generate the nanorobotic 3D microgels. We use microfluidic encapsulation to physically embed the nanoactuators in an alginate network, to form the microgel droplets. The nanoactuators respond to near-infrared light owing to the synergistic effects of plasmonic and thermoresponsive components, and the nanorobotic 3D microgels generate compressive force under the same light stimulus. We use a multiscale approach to characterize this behavior for both the nanoactuators and the assembled microgels via dynamic light scattering and fluorescence microscopy, respectively. A thermoresponsive fluorescent molecule, Rhodamine B, is integrated into alginate chains to monitor the temperature of the microgels (22-59 °C) during actuation at laser intensities up to 6.4 μW μm-2. Our findings show that nanoactuators and the microgels exhibit reversible deformation above the lower critical solution temperature of the thermoresponsive polymer at 42 °C. 785 nm laser light triggers the generation of 2D radial strain in nanoactuators at a maximum of 44%, which translates to an average 2D radial strain of 2.1% in the nanorobotic microgels at 26.4 vol% nanoactuator loading. We then use a semi-experimental approach to quantify the photothermally generated forces in the microgels. Finite element modeling coupled with experimental measurements shows that nanorobotic microgels generate up to 8.5 nN of force over encapsulated single cells. Overall, our method provides a comprehensive approach to characterizing the mechanical performance of nanorobotic hydrogel networks.

Alginate-Based Encapsulation Fabrication Technique for Drug Delivery: An Updated Review of Particle Type, Formulation Technique, Pharmaceutical Ingredient, and Targeted Delivery System

Alginate is a natural biopolymer widely studied for pharmaceutical applications due to its biocompatibility, low toxicity, and mild gelation abilities. This review summarizes recent advances in alginate-based encapsulation systems for targeted drug delivery. Alginate formulations like microparticles, nanoparticles, microgels, and composites fabricated by methods including ionic gelation, emulsification, spray drying, and freeze drying enable tailored drug loading, enhanced stability, and sustained release kinetics. Alginate microspheres prepared by spray drying or ionic gelation provide gastric protection and colon-targeted release of orally delivered drugs. Alginate nanoparticles exhibit enhanced cellular uptake and tumor-targeting capabilities through the enhanced permeation and retention effect. Crosslinked alginate microgels allow high drug loading and controlled release profiles. Composite alginate gels with cellulose, chitosan, or inorganic nanomaterials display improved mechanical properties, mucoadhesion, and tunable release kinetics. Alginate-based wound dressings containing antimicrobial nanoparticles promote healing of burns and chronic wounds through sustained topical delivery. Although alginate is well-established as a pharmaceutical excipient, more extensive in vivo testing is needed to assess clinical safety and efficacy of emerging formulations prior to human trials. Future opportunities include engineered systems combining stimuli-responsiveness, active targeting, and diagnostic capabilities. In summary, this review discusses recent advances in alginate encapsulation techniques for oral, transdermal, and intravenous delivery, with an emphasis on approaches enabling targeted and sustained drug release for enhanced therapeutic outcomes.

Structure-activity relationships of bioactive polysaccharides extracted from macroalgae towards biomedical application: A review

Macroalgae are valuable and structurally diverse sources of bioactive compounds among marine resources. The cell walls of macroalgae are rich in polysaccharides which exhibit a wide range of biological activities, such as anticoagulant, antioxidant, antiviral, anti-inflammatory, immunomodulatory, and antitumor activities. Macroalgae polysaccharides (MPs) have been recognized as one of the most promising candidates in the biomedical field. However, the structure-activity relationships of bioactive polysaccharides extracted from macroalgae are complex and influenced by various factors. A clear understanding of these relationships is indeed critical in developing effective biomedical applications with MPs. In line with these challenges and knowledge gaps, this paper summarized the structural characteristics of marine MPs from different sources and relevant functional and bioactive properties and particularly highlighted those essential effects of the structure-bioactivity relationships presented in biomedical applications. This review not only focused on elucidating a particular action mechanism of MPs, but also intended to identify a novel or potential application of these valued compounds in the biomedical field in terms of their structural characteristics. In the last, the challenges and prospects of MPs in structure-bioactivity elucidation were further discussed and predicted, where they were emphasized on exploring modern biotechnology approaches potentially applied to expand their promising biomedical applications.

Biomaterials barcoding: a high-throughput breakthrough

In the world of biomedical breakthroughs, Rice University bioengineer Omid Veiseh and his team are making waves with their recent publication in Nature Biomedical Engineering (2023) (Mukherjeeet al., Nat Biomed Eng. 7:867–886, 2023). This study is a pivotal step in our fight against fibrosis, an issue that has long hindered medical progress. Their pioneering research isn’t just a scientific milestone; it’s a game-changer in how we tackle tissue scarring. Veiseh and his team have introduced an innovative method that allows for rapid testing of various materials within living organisms. By employing cellular barcoding and cutting-edge sequencing techniques, they’ve accelerated the assessment of multiple hydrogels. As we delve deeper into the specifics of this groundbreaking study, we uncover not just scientific insights, but the potential to revolutionize how we conceptualize and utilize biomaterials. This discussion isn’t merely about research methods; it’s about the ray of hope and boundless opportunities this study illuminates across the spectrum of biomaterials science.

Alginate biopolymeric structures: Versatile carriers for bioactive compounds in functional foods and nutraceutical formulations: A review

Alginate-based biopolymer products have gained attention for protecting and delivering bioactive components in nutraceuticals and functional foods. These naturally abundant anionic, unbranched, and linear copolymers are also produced commercially by microorganisms. Alone or in combination with other copolymers, they efficiently transport bioactive molecules in food and nutraceutical products. This review aims to provide an in-depth understanding of alginate-based products and structures, emphasizing their role in delivering functional molecules in various formulations and delivery systems. These include edible coatings/films, gels/emulsions, beads/droplets, microspheres/particles, and engineered nanostructures where alginates have been used potentially. By exploring these applications, readers gain insights into the benefits of these products. Because, alginate-based biopolymer products have shown promise in delivering bioactive compounds like vitamin C, vitamin D3, curcumin, β-carotene, resveratrol, folic acid, gliadins, caffeic acid, betanin, limonoids, quercetin, several polyphenols and essential oils, etc., which are chief contributors to treating specific/overall nutritional and chronic metabolic disorders. So, this review summarizes the potential of alginate-based structures/products in various forms for delivering a wide range of functional food ingredients and nutraceutical components that offer promising perspectives for future investigations.

A Mucin-Based Bio-Ink for 3D Printing of Objects with Anti-Biofouling Properties

With its potential to revolutionize the field of personalized medicine by producing customized medical devices and constructs for tissue engineering at low costs, 3D printing has emerged as a highly promising technology. Recent advancements have sparked increasing interest in the printing of biopolymeric hydrogels. However, owing to the limited printability of those soft materials, the lack of variability in available bio-inks remains a major challenge. In this study, a novel bio-ink is developed based on functionalized mucin-a glycoprotein that exhibits a multitude of biomedically interesting properties such as immunomodulating activity and strong anti-biofouling behavior. To achieve sufficient printability of the mucin-based ink, its rheological properties are tuned by incorporating Laponite XLG as a stabilizing agent. It is shown that cured objects generated from this novel bio-ink exhibit mechanical properties partially similar to that of soft tissue, show strong anti-biofouling properties, good biocompatibility, tunable cell adhesion, and immunomodulating behavior. The presented findings suggest that this 3D printable bio-ink has a great potential for a wide range of biomedical applications, including tissue engineering, wound healing, and soft robotics.

Alginate/chitosan hydrogels as perspective transport systems for cefotaxime

This work reports synthesis of pH-responsive alginate/chitosan hydrogel spheres with the average diameter of 2.0 ± 0.05 mm, which contain cefotaxime that is an antibiotic of the cefalosporine group. The spheres provided the cefotaxime encapsulation efficiency of 95 ± 1%. An in vitro release of cefotaxime from the spheres in the media that simulate human biological fluids in peroral delivery conditions was found to be a pH-dependent process. The analysis of cefotaxime release kinetics by the Korsmeyer-Peppas model revealed a non-Fickian mechanism of its diffusion, which may be related to intermolecular interactions occurring between the antibiotic and chitosan. Conductometry, UV spectroscopy, and IR spectroscopy were used to study complexation of chitosan with cefotaxime in aqueous media with varied pH, characterize the composition of the complexes, and calculate their stability constants. The composition of the cefotaxime-chitosan complexes was found to correspond to the 1.0:4.0 and 1.0:2.0 molar ratios of the components at pH 2.0 and 5.6, respectively. Quantum chemical modeling was used to evaluate energy characteristics of chitosan-cefotaxime complexation considering the influence of a solvent.

Enhancing the properties of electrospun polyvinyl Alcohol/Oxidized sodium alginate nanofibers with fluorescence carbon Dots: Preparation and characterization

The objective of this study was to develop fluorescence nanofibrous polyvinyl alcohol/oxidized sodium alginate (PVA-OSA) incorporated with carbon dots (CDs) through Schiff-base interaction. The carbon dots used in this study were derived from the polyphenol-enriched extract of pomegranate peel, as established in previous work, as the reinforcing and antioxidant agent to enhance the physicochemical and biological properties of the nanofibers were used. The fabricated nanofibers were characterized using FE-SEM, FT-IR, XRD, and DSC analysis. The FE-SEM results revealed that an increase in the number of CDs in the nanofibers led to a decrease in diameter (809.6 ± 77.1 nm to 273.16 ± 41.1 nm). Furthermore, surface modification caused a significant reduction in the amount of surface roughness of the nanofibers. Incorporating CDs not only reduced the scaffold diameter but also improved its mechanical properties and promoted the growth of fibroblast cells. The ultimate tensile strength of scaffolds with and without CDs was 2.15 ± 0.02 MPa and 1.53 ± 0.74 MPa respectively. The influence of CDs amount on the properties of nanofibers showed that the swelling capacity and degradability of nanofibers can be adjusted by changing the range of CDs. Apart from the aforementioned benefits of incorporating CDs in improving nanofiber properties, their exceptional antioxidant properties can be harnessed for protecting nanofibers against oxidation and as a healing agent in wound dressings.

Mechanical Properties of Alginate Hydrogels Cross-Linked with Multivalent Cations

Ionically, cross-linked alginate gels have a potential to be used in a wide range of biomedical, environmental and catalytic applications. The study deals with preparation of alginate hydrogels cross-linked with various cations and the analysis of their equilibrium swelling and mechanical properties. It is shown that the type of cations used in the cross-linking process affects the elastic moduli and the equilibrium degree of swelling of the gels. The experimental data in small-amplitude oscillatory tests are fitted with a model that involves two material parameters: the elastic modulus of a polymer network and a measure of its inhomogeneity. The influence of cations on these quantities is studied numerically. It is revealed that the dependence of the elastic modulus of ionically cross-linked alginate gels on their equilibrium degree of swelling differs from that predicted by the conventional theory for covalently cross-linked gels.

Physicochemical properties and compatibility of sodium alginate and fucoidan solutions

The interaction between linear sodium alginate and branched fucoidan were investigated using viscosity and tensiometric measurements. It was shown that water-soluble interpolymer complex is formed. The alginate-fucoidan complexation is due to the formation of a cooperative system of hydrogen bonds between the ionogenic and hidroxyl groups of sodium alginate and fucoidan and hydrophobic interactions. The intensity of the polysaccharide-polysaccharide interaction increases with an increase in the content of fucoidan in the blend. It was established that alginate and fucoidan are weak surfactants of the associative type. The surface activity of fucoidan was 34.6 mN∙m²/mol, and for alginate was 20.7 mN∙m²/mol. The resulting alginate-fucoidan interpolymer complex exhibits high surface activity and indicates a synergistic effect of combining two polysaccharides. The values of the activation energy of the viscous flow process were 7.0 kJ∙mol^-1, 16.2 for kJ∙mol^-1 and 33.9 kJ∙mol^-1for alginate, fucoidan and their blend, respectively. These studies provide a methodological basis for determining the conditions for preparation of homogeneous film materials with a certain complex of physico-chemical and mechanical properties.

Sodium alginate reinforced polyacrylamide/xanthan gum double network ionic hydrogels for stress sensing and self-powered wearable device applications

Strong and ductile sodium alginate (SA) reinforced polyacrylamide (PAM)/xanthan gum (XG) double network ionic hydrogels were constructed for stress sensing and self-powered wearable device applications. In the designed network of PXS-Mⁿ⁺/LiCl (short for PAM/XG/SA-Mⁿ⁺/LiCl, where Mⁿ⁺ stands for Fe³⁺, Cu²⁺ or Zn²⁺), PAM acts as a flexible hydrophilic skeleton, and XG functions as a ductile second network. The macromolecule SA interacts with metal ion Mⁿ⁺ to form a unique complex structure, significantly improving the mechanical strength of the hydrogel. The addition of inorganic salt LiCl endows the hydrogel with high electrical conductivity, and meanwhile reduces the freezing point and prevents water loss of the hydrogel. PXS-Mⁿ⁺/LiCl exhibits excellent mechanical properties and ultra-high ductility (a fracture tensile strength up to 0.65 MPa and a fracture strain up to 1800%), and high stress-sensing performance (a high GF up to 4.56 and pressure sensitivity of 0.122). Moreover, a self-powered device with a dual-power-supply mode, i.e., PXS-Mⁿ⁺/LiCl-based primary battery and TENG, and a capacitor as the energy storage component was constructed, which shows promising prospects for self-powered wearable electronics.

3D-Printed Functional Hydrogel by DNA-Induced Biomineralization for Accelerated Diabetic Wound Healing

Chronic wounds in diabetic patients are challenging because their prolonged inflammation makes healing difficult, thus burdening patients, society, and health care systems. Customized dressing materials are needed to effectively treat such wounds that vary in shape and depth. The continuous development of 3D-printing technology along with artificial intelligence has increased the precision, versatility, and compatibility of various materials, thus providing the considerable potential to meet the abovementioned needs. Herein, functional 3D-printing inks comprising DNA from salmon sperm and DNA-induced biosilica inspired by marine sponges, are developed for the machine learning-based 3D-printing of wound dressings. The DNA and biomineralized silica are incorporated into hydrogel inks in a fast, facile manner. The 3D-printed wound dressing thus generates provided appropriate porosity, characterized by effective exudate and blood absorption at wound sites, and mechanical tunability indicated by good shape fidelity and printability during optimized 3D printing. Moreover, the DNA and biomineralized silica act as nanotherapeutics, enhancing the biological activity of the dressings in terms of reactive oxygen species scavenging, angiogenesis, and anti-inflammation activity, thereby accelerating acute and diabetic wound healing. These bioinspired 3D-printed hydrogels produce using a DNA-induced biomineralization strategy are an excellent functional platform for clinical applications in acute and chronic wound repair.

Xanthan-Based Materials as a Platform for Heparin Delivery

Heparin (Hep), with its anticoagulant activity, antiangiogenic and apoptotic effects, and growth factor binding, plays an important role in various biological processes. Formulations as drug delivery systems protect its biological activity, and limit the potential side effects of faulty administration. The objective of this study was to develop novel xanthan-based materials as a delivery carrier for heparin. The materials exhibited remarkable elastic behavior and toughness without any crack development within the network, which also support their application for tissue engineering. It was found that all materials possessed the ability to control the release of heparin, according to the Korsmeyer-Peppas release model. All Hep-containing materials caused significant exchanges of the activated partial thromboplastin time (aPTT) and prothrombin time (PT) parameters, indicating that formulated natural/natural synthetic polymeric networks conserved heparin's biological activity and its ability to interrupt the blood coagulation cascade. The obtained results confirmed that developed materials could be carriers for the controlled release of heparin, with potential applications in topical administration.

Swelling of Homogeneous Alginate Gels with Multi-Stimuli Sensitivity

A new two-step method is suggested for the preparation of homogeneous alginate gels. In the first step, alginate chains are weakly bonded by Ca2+ ions in an aqueous solution with a low pH. In the next step, the gel is immersed into a strong solution of CaCl2 to finalize the cross-linking process. Homogeneous alginate gels preserve their integrity in aqueous solutions with a pH ranging from 2 to 7 and ionic strength in the interval from 0 to 0.2 M, at temperatures ranging from room temperature up to 50 °C, and can be used in biomedical applications. The immersion of these gels into aqueous solutions with low pH induces the partial breakage of ionic bonds between chains (treated as gel degradation). This degradation affects the equilibrium and transient swelling of homogeneous alginate gels and makes them sensitive to the history of loading and environmental conditions (pH, ionic strength and temperature of aqueous solutions). As sensitivity to the environmental stimuli is a characteristic feature of polymer networks connected by catch bonds, homogeneous alginate gels may serve as a simple model, mimicking the behavior of more sophisticated structures in living matter.

Alginate Ag/AgCl Nanoparticles Composite Films for Wound Dressings with Antibiofilm and Antimicrobial Activities

Recently, silver-based nanoparticles have been proposed as components of wound dressings due to their antimicrobial activity. Unfortunately, they are cytotoxic for keratinocytes and fibroblasts, and this limits their use. Less consideration has been given to the use of AgCl nanoparticles in wound dressings. In this paper, a sustainable preparation of alginate AgCl nanoparticles composite films by simultaneous alginate gelation and AgCl nanoparticle formation in the presence of CaCl₂ solution is proposed with the aim of obtaining films with antimicrobial and antibiofilm activities and low cytotoxicity. First, AgNO₃ alginate films were prepared, and then, gelation and nanoparticle formation were induced by film immersion in CaCl₂ solution. Films characterization revealed the presence of both AgCl and metallic silver nanoparticles, which resulted as quite homogeneously distributed, and good hydration properties. Finally, films were tested for their antimicrobial and antibiofilm activities against Staphylococcus epidermidis (ATCC 12228), Staphylococcus aureus (ATCC 29213), Pseudomonas aeruginosa (ATCC 15692), and the yeast Candida albicans. Composite films showed antibacterial and antibiofilm activities against the tested bacteria and resulted as less active towards Candida albicans. Film cytotoxicity was investigated towards human dermis fibroblasts (HuDe) and human skin keratinocytes (NCTC2544). Composite films showed low cytotoxicity, especially towards fibroblasts. Thus, the proposed sustainable approach allows to obtain composite films of Ag/AgCl alginate nanoparticles capable of preventing the onset of infections without showing high cytotoxicity for tissue cells.

Renewable marine polysaccharides for microenvironment-responsive wound healing

Marine polysaccharides (MPs) are an eco-friendly and renewable resource with a distinctive set of biological functions and are regarded as biological materials that can be in contact with tissues and body fluids for an extended time and promote tissue or organ regeneration. Skin tissue is easily invaded by the external environment due to its softness and large surface area. However, the body's natural physiological healing process is often too slow or suffers from the incomplete restoration of skin structure and function. Functional wound dressings are crucial for skin tissue engineering. Herein, popular MPs from different sources are summarized systematically. In particular, the structure-effectiveness of MP-based wound dressings and the physiological remodeling process of different wounds are reviewed in detail. Finally, the prospect of MP-based smart wound dressings is stated in conjunction with the wound microenvironment and provides new opportunities for high-value biomedical applications of MPs.

Light-Programmable Nanocomposite Hydrogel for State-Switchable Wound Healing Promotion and Bacterial Infection Elimination

Developing an ideal wound dressing that not only accelerates wound healing but also eliminates potential bacterial infections remains a difficult balancing act. This work reports the design of a light-programmable sodium alginate nanocomposite hydrogel loaded with BiOCl/polypyrrole (BOC/PPy) nanosheets for state-switchable wound healing promotion and bacterial infection elimination remotely. The nanocomposite hydrogel possesses programmable photoelectric or photothermal conversion due to the expanded light absorption range, optimized electron transmission interface, promoted photo-generated charge separation, and transfer of the BOC/PPy nanosheets. Under white light irradiation state, the nanocomposite hydrogel induces human umbilical vein endothelial cells migration and angiogenesis, and accelerates the healing efficiency of mouse skin in vivo. Under near-infrared light irradiation state, the nanocomposite hydrogel presents superior antibacterial capability in vitro, and reaches an antibacterial rate of 99.1% for Staphylococcus aureus infected skin wound in vivo. This light-programmable nanocomposite hydrogel provides an on-demand resolution of biological state-switching to balance wound healing and elimination of bacterial infection.

Self-Healing Alginate Hydrogel Formed by Dynamic Benzoxaborolate Chemistry Protects Retinal Pigment Epithelium Cells against Oxidative Damage

Oxidative stress is considered as a major factor causing retinal pigment epithelium (RPE) dysfunction and finally leading to retinal diseases such as age-related macular degeneration (AMD). Developing hydrogels for RPE cell delivery, especially those with antioxidant feature, is emerging as a promising approach for AMD treatment. Herein, a readily prepared antioxidant alginate-based hydrogel was developed to serve as a cytoprotective agent for RPE cells against oxidative damage. Alg-BOB was synthesized via conjugation of benzoxaborole (BOB) to the polysaccharide backbone. Hydrogels were formed through self-crosslinking of Alg-BOB based on benzoxaborole-diol complexation. The resulting hydrogel showed porous micro-structure, pH dependent mechanical strength and excellent self-healing, remolding, and injectable properties. Moreover, the hydrogel exhibited excellent cytocompatibility and could efficiently scavenge reactive oxygen species (ROS) to achieve an enhanced viability of ARPE-19 cells under oxidative condition. Altogether, our study reveals that the antioxidant Alg-BOB hydrogel represents an eligible candidate for RPE delivery and AMD treatment.

A Shapable Alginate Hydrogel Resolving the Conflicts between Multifunctionality and Fabrication Simplicity

Alginate is a naturally derived biocompatible polymer widely used as a drug or food adjuvant. However, its usage as a biofunctional material has been confounded by the lack of shapable strategies. In this study, we report an easily applied ionic cross-linking strategy for fabricating shapable multifunctional SA-Ca(II) hydrogels employing the process of regulated diffusion. The fabrication proceeds in neutral solutions under ambient conditions. The obtained SA-Ca(II) hydrogel presents tunable moduli ranging from 4 to 30 kPa, resembling a series of human tissues. The tunable mechanical strength provides differentiation signals for stem cell polarization. The hydrogel film can lift a weight of 10 kg. The hydrogel can be prepared into various shapes and remains stable over one year upon rinsing in deionized water, but rapidly degrades in alginate lyase solutions. Subcutaneously embedded SA-Ca(II) hydrogels in mice show high biocompatibility and degrade over 4 weeks accompanied by hair follicle regeneration. Wearable protections as well as stimuli-responsive electronic circuits are then achieved, which not only protect the model body against high-temperature environments but also show warning signals when the protection loses effectiveness because of high temperatures. Overall, these results demonstrate that our SA-Ca(II) hydrogel offers appealing comprehensive functionalities from multifaceted perspectives, including mechanical strength, economic and environmental considerations, transparency, forming capability, biocompatibility, and conductivity.

3D Scaffolds Fabrication via Bicomponent Microgels Assembly: Process Optimization and In Vitro Characterization

In the last decade, different technological approaches have been proposed for the fabrication of 3D models suitable to evaluate in vitro cell response. Among them, electro fluid dynamic atomization (EFDA) belonging to the family of electro-assisted technologies allows for the dropping of polysaccharides and/or proteins solutions to produce micro-scaled hydrogels or microgels with the peculiar features of hydrogel-like materials (i.e., biocompatibility, wettability, swelling). In this work, a method to fabricate 3D scaffolds by the assembly of bicomponent microgels made of sodium alginate and gelatin was proposed. As first step, optical and scanning electron microscopy with the support of image analysis enabled to explore the basic properties of single blocks in terms of correlation between particle morphology and process parameters (i.e., voltage, flow rate, electrode gap, and needle diameter). Chemical analysis via ninhydrin essays and FTIR analysis confirmed the presence of gelatin, mostly retained by physical interactions into the alginate network mediated by electrostatic forces. In vitro tests confirmed the effect of biochemical signals exerted by the protein on the biological response of hMSCs cultured onto the microgels surface. Hence, it is concluded that alginate/gelatin microgels assemblies can efficiently work as 3D scaffolds able to support in vitro cells functions, thus providing a friendly microenvironment to investigate in vitro cell interactions.

Herb Polysaccharide-Based Drug Delivery System: Fabrication, Properties, and Applications for Immunotherapy

Herb polysaccharides (HPS) have been studied extensively for their healthcare applications. Though the toxicity was not fully clarified, HPS were widely accepted for their biodegradability and biocompatibility. In addition, as carbohydrate polymers with a unique chemical composition, molecular weight, and functional group profile, HPS can be conjugated, cross-linked, and functionally modified. Thus, they are great candidates for the fabrication of drug delivery systems (DDS). HPS-based DDS (HPS-DDS) can bypass phagocytosis by the reticuloendothelial system, prevent the degradation of biomolecules, and increase the bioavailability of small molecules, thus exerting therapeutic effects. In this review, we focus on the application of HPS as components of immunoregulatory DDS. We summarize the principles governing the fabrication of HPS-DDS, including nanoparticles, micelles, liposomes, microemulsions, hydrogels, and microneedles. In addition, we discuss the role of HPS in DDS for immunotherapy. This comprehensive review provides valuable insights that could guide the design of effective HPS-DDS.

Alginate-reinforced poly(3-hydroxybutyrate)/ poly(hydroxybutyrate-co-hydroxyvalerate) aerogel monoliths fabricated by phase separation as environmental floating adsorbents

Poly(3-hydroxybutyrate) (PHB)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) aerogel monoliths were prepared via nonsolvent induced phase separation and then sequentially immersed in ethanol and sodium alginate (ALG) solutions. The resulting composite aerogels contained up to a 52 wt% fraction ALG, causing a remarkable increase in their compressive modulus and collapse strength from 0.3 MPa and 33 kPa to 4 MPa and 406 kPa, respectively, i.e., by 13/12 times. An increase in the ALG contents in the composite aerogels allowed them to effectively adsorb both water and soybean oil, according to pseudo-second-order adsorption kinetics. The highly porous composite aerogel acted as an efficient floating adsorbent for a cationic dye (i.e., methylene blue (MB)) in water. MB adsorption was found to be strongly dependent on ALG contents in the adsorbent, as well as operating parameters such as the initial concentration, pH, and temperature of MB solutions. MB adsorption is best described by the Langmuir isotherm and follows pseudo-second-order kinetics. Ca²⁺-crosslinking of ALG further increased compressive strength but significantly decreased MB adsorption capability following pseudo-first-order kinetics, implying a slow internal diffusion step for MB adsorption due to its tightened network structure relative to noncrosslinked adsorbents.

Transformable Gallium-Based Liquid Metal Nanoparticles for Tumor Radiotherapy Sensitization

The past decades have witnessed an increasing interest in the exploration of room temperature gallium-based liquid metal (LM) in the field of microfluidics, soft robotics, electrobiology, and biomedicine. Herein, this study for the first time reports the utilization of nanosized gallium-indium eutectic alloys (EGaIn) as a radiosensitizer for enhancing tumor radiotherapy. The sodium alginate (Alg) functionalized EGaIn nanoparticles (denoted as EGaIn@Alg NPs) are prepared via a simple one-step synthesis method. The coating of Alg not only prevents the aggregation and oxidation of EGaIn NPs in an aqueous solution but also enables them low cytotoxicity, good biocompatibility, and in-situ formation of gels in the Ca²⁺ enriched tumor physiological microenvironment. Due to the metallic nature and high density, EGaIn can increase the generation of reactive oxygen species under the irradiation of X-ray, which can not only directly promote DNA damage and cell apoptosis, but also show an efficient tumor inhibition rate in vivo. Moreover, EGaIn@Alg NPs hold good performance as computed tomography (CT) and photoacoustic tomography (PAT) imaging contrast agents. This work provides an alternative nanotechnology strategy for tumor radiosensitization and also enlarges the biomedical application of gallium-based LM.

Glassy-like Metal Oxide Particles Embedded on Micrometer Thicker Alginate Films as Promising Wound Healing Nanomaterials

Micrometer-thicker, biologically responsive nanocomposite films were prepared starting from alginate-metal alkoxide colloidal solution followed by sol-gel chemistry and solvent removal through evaporation-induced assembly. The disclosed approach is straightforward and highly versatile, allowing the entrapment and growth of a set of glassy-like metal oxide within the network of alginate and their shaping as crake-free transparent and flexible films. Immersing these films in aqueous medium triggers alginate solubilization, and affords water-soluble metal oxides wrapped in a biocompatible carbohydrate framework. Biological activity of the nano-composites films was also studied including their hemolytic activity, methemoglobin, prothrombin, and thrombine time. The effect of the films on fibroblasts and keratinocytes of human skin was also investigated with a special emphasis on the role played by the incorporated metal oxide. This comparative study sheds light on the crucial biological response of the ceramic phase embedded inside of the films, with titanium dioxide being the most promising for wound healing purposes.