Evaluating the Efficiency of Cadmium Removal by Alginate Hydrogels from Water Using 5,7-Dibromo-8-hydroxyquinoline as a Complexing Reagent

Cadmium toxicity in wastewater is a rising concern due to industries like batteries,metallurgy,electroplating,plastic stabilizers,and pigments.The quantitative detection of Cd^(2+)and its remediation from wastewater samples are of major concern from an environmental point of view.In the present work,an effective spectrophotometric method has been reported using 5,7-dibromo-8-hydroxyquinoline(DBHQ)as a complexing agent for Cd^(2+).This method has advantages like using recyclable,less toxic solvents and easy sample preparation.The limit of detection,limit of quantification,and sensitivity of the proposed method were found to be 33.30,36.70 mg L^(−1),and 2×10^(−3),respectively.The DBHQ method was validated using atomic absorption spectroscopy,and the recovery percentage was more than 98%.These results indicate that DBHQ can be effectively used for monitoring Cd^(2+)in aqueous systems.The method developed was further employed for monitoring Cd^(2+)adsorption on calcium alginate(AL)hydrogels.Batch adsorption studies were done to optimize parameters of Cd^(2+)removal using AL hydrogels,and the data obtained were used for kinetic and thermodynamic studies.Kinetic studies indicated that the pseudo-first-order model showed better fitting,and thermodynamic studies showed Freundlich-like adsorption.The maximum adsorption capacity of Cd^(2+)on AL hydrogels was found to be 56.45 mg g^(−1).The validation studies of DBHQ were performed using statistical analysis methods like t-tests and one-way variance.

Advances in fabricating spherical alginate hydrogels with controlled particle designs by ionotropic gelation as encapsulation systems

Alginate is a biopolymer that has exceptional gelling properties, which allow easy gel formation under safe and mild conditions. Consequently, it is often used to encapsulate a variety of cargos, such as cells, enzymes, and lipids, and is typically employed as a model to study hydrogel-based encapsulation sys- tems. Since the first use of alginate in the encapsulation field in the 1970s, many methods have been developed to produce alginate hydrogel particles of different sizes, structures, and morphologies. This review provides an overview of the current progress in the fabrication of alginate hydrogels with vari- ous particle designs, including a discussion of dispersion techniques to pre-template alginate particles, gelation mechanisms, considerations in selecting suitable fabrication methods, and future directions.

Studies on the PEO-PPO-PEO Block Copolymer Release from Alginate Hydrogel

Alginate hydrogel is one of the most widely used carriers for the immobilization of microbial cells. If surfactants are encapsulated with alginate hydrogel, increasing temperature or concentration can make the encapsulated surfactants aggregate and form micelle.

Evaluation of the effectiveness of alginate-based hydrogels in preventing peritoneal adhesions

Infertility and intestinal blockage are just two examples of the postoperative consequences that can arise from peritoneal damage,which can also result in severe peritoneal fibrosis and peritoneal adhesions.Peritoneal adhesions are still not effectively treated,and both pharmaceutical therapy and biomaterial barriers have only had modest preventative effects.In this work,we looked into the effectiveness of in-place injectable sodium alginate hydrogel for peritoneal adhesion prevention.The findings demonstrated that sodium alginate hydrogel promoted human peritoneal mesothelial cell proliferation and migration,prevented peritoneal fibrosis by suppressing the production of transforming growth factor-β1,and,most importantly,promoted mesothelium self-repair.These findings imply that this brand-new sodium alginate hydrogel is a good candidate material for peritoneal adhesion prevention.

Promotion of microvasculature formation in alginate composite hydrogels by an immobilized peptide GYIGSRG

The ability to create artificial thick tissues is a major tissue engineering problem, requiring the formation of a suitable vascular supply. In this work we examined the ability of inducing angiogenesis in a bioactive hydrogel. GYIGSRG （NH2-Gly-Tyr-Ile- Gly-Ser-Arg-Gly-COOH, GG） has been conjugated to sodium alginate （ALG） to synthesize a biological active biomaterial ALG-GG. The product was characterized by IH NMR, FT-IR and elemental analysis. A series of CaCO3/ALG-GG composite hydrogels were prepared by crosslinking ALG-GG with D-glucono-8-1actone/calcium carbonate （GDL/CaCO3） in different molar ratios. The mechanical strength and swelling ratio of the composite hydrogels were studied. The results revealed that both of them can be regulated under different preparation conditions. Then, CaCO3/ALG-GG composite hydrogel was im- planted in vivo to study the ability to induce angiogenesis. The results demonstrated that ALG-GG composited hydrogel can induce angiogenesis significantly compared with non-modified ALG group, and it may be valuable in the development of thick tissue engineering scaffold.

Bone-derived MSCs encapsulated in alginate hydrogel prevent collagen-induced arthritis in mice through the activation of adenosine A_(2A/2B)receptors in tolerogenic dendritic cells

Tolerogenic dendritic cells(tol DCs)facilitate the suppression of autoimmune responses by differentiating regulatory T cells(Treg).The dysfunction of immunotolerance results in the development of autoimmune diseases,such as rheumatoid arthritis(RA).As multipotent progenitor cells,mesenchymal stem cells(MSCs),can regulate dendritic cells(DCs)to restore their immunosuppressive function and prevent disease development.However,the underlying mechanisms of MSCs in regulating DCs still need to be better defined.Simultaneously,the delivery system for MSCs also influences their function.Herein,MSCs are encapsulated in alginate hydrogel to improve cell survival and retention in situ,maximizing efficacy in vivo.The three-dimensional co-culture of encapsulated MSCs with DCs demonstrates that MSCs can inhibit the maturation of DCs and the secretion of pro-inflammatory cytokines.In the collagen-induced arthritis(CIA)mice model,alginate hydrogel encapsulated MSCs induce a significantly higher expression of CD39^(+)CD73^(+)on MSCs.These enzymes hydrolyze ATP to adenosine and activate A_(2A/2B)receptors on immature DCs,further promoting the phenotypic transformation of DCs to tol DCs and regulating naive T cells to Tregs.Therefore,encapsulated MSCs obviously alleviate the inflammatory response and prevent CIA progression.This finding clarifies the mechanism of MSCs-DCs crosstalk in eliciting the immunosuppression effect and provides insights into hydrogel-promoted stem cell therapy for autoimmune diseases.

Enrichment of Cd^(2＋) from water with a calcium alginate hydrogel filtration membrane

A new method was developed for effective enrichment of Cd2+ ions from water with a calcium alginate(CaAlg) hydrogel filtration membrane. First, the CaAlg hydrogel filtration membrane was prepared without a pore-forming agent. This membrane was used to remove Cd^(2+) via ion exchange with Ca^(2+), and the Cd^(2+) was preserved in the CaAlg hydrogel. Then, the CaAlg hydrogel containing Cd^(2+) was soaked in a sodium citrate solution, and the hydrogel was fully dissolved. The removal rate of the CaAlg filtration membrane reached almost 100% within 120 min when the Cd^(2+) concentration was under 1 mg/L. Factors affecting the removal rate were investigated, such as NaAlg concentration, operating pressure, operating time and the initial concentration of Cd^(2+). The effects of initial Cd^(2+) concentration, pressure and filtration time on the enrichment factor were also investigated. The results show that the enrichment factor reached 87.3 when the pressure was 0.18 MPa and the filtration time was 240 min. Different enrichment factors could be achieved by adjusting the operating pressure and filtration time.

Coaxial Embedded Printing of Gelatin Methacryloyl-alginate Double Network Hydrogel for Multilayer Vascular Tubes

The reconstruction of vascular-like tissues exhibiting a typical three-layer structure in vitro is vital to bio-fabrication research.It enables the realization of more complicated micro-environments,such as myocardium,liver,and tumor,which enables us to investigate their specific physiological phenomena or pathological mecha-nisms.Herein,we propose a coaxial embedded printing method,where the gelatin methacrylate(GelMA)-alginate composite hydrogel and sacrificial materials are extruded from a coaxial nozzle into a cylinder mold.By applying this method,we achieve the rapid fabrication of multilayer tube structures with inner diameters ranging from 400 to 1000μm.In addition,myoblasts are encapsulated in the hydrogel,and the cells show high viability.Moreover,we encapsulate smooth muscle cells(SMCs)and the human umbilical vein endothelial cells-T1(HUVEC-T1)cell line in the hydrogel to form vascular-like tissues,and the cells exhibit good morphology and protein expression.These results suggest that a vascular tube fabricated using the proposed method can serve as a vascular model for in vitro studies.

Phase-change composite filled natural nanotubes in hydrogel promote wound healing under photothermally triggered drug release

It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance.The construction of smart release nanocontainers responsive to near-infrared(NIR)laser irradiation in an on-demand and stepwise way is a promising strategy for avoiding the emergence of multidrug-resistant bacteria.Here,we develop a hydrogel composite made of alginate and nanotubes with an efficient NIR-triggered release of rifampicin and outstanding antibacterial ability.This composite hydrogel is prepared through co-encapsulating antibacterial drug(rifampicin),NIR-absorbing dye(indocyanine green),and phase-change materials(a eutectic mixture of fatty acids)into halloysite nanotubes,followed by incorporation into alginate hydrogels,allowing the in-situ gelation at room temperature and maintaining the integrity of drug-loaded nanotubes.Among them,the eutectic mixture with a melting point of 39℃ serves as the biocompatible phase-change material to facilitate the NIR-triggered drug release.The resultant phase-change material gated-nanotubes exhibit a prominent photothermal efficiency with multistep drug release under laser irradiation.In an in vitro assay,composite hydrogel provides good antibacterial potency against Staphylococcus aureus,one of the most prevalent microorganisms of dangerous gas gangrene.A bacterial-infected rat full-thickness wound model demonstrates that the NIR-responsive composite hydrogel inhibits the bacteria colonization and suppresses the inflammatory response caused by bacteria,promoting angiogenesis and collagen deposition to accelerate wound regeneration.The NIR-responsive composite hydrogel has a great po-tential as an antibacterial wound dressing functionalized with controlled multistep treatment of the infected sites.

A hydrogel spinal dural patch with potential anti-inflammatory,pain relieving and antibacterial effects

CSFL caused by spinal dural defect is a common complication of spinal surgery,which need repair such as suture or sealants.However,low intracranial pressure symptoms,wound infection and prolonged hospital associated with pin-hole leakage or loose seal effect were often occurred after surgical suture or sealants repair.Stable,pressure resistance and high viscosity spinal dural repair patch in wet environment without suture or sealants was highly needed.Herein,a bioactive patch composed of alginate and polyacrylamide hydrogel matrix cross-linked by calcium ions,and chitosan adhesive was proposed.This fabricated patch exhibits the capabilities of promoting defect closure and good tight seal ability with the bursting pressure is more than 790 mm H2O in wet environment.In addition,the chitosan adhesive layer of the patch could inhibit the growth of bacterial in vitro,which is meaningful for the postoperative infection.Furthermore,the patch also significantly reduced the expression of GFAP,IBA-1,MBP,TNF-α,and COX-2 in early postoperative period in vivo study,exerting the effects of anti-inflammatory,analgesic and adhesion prevention.Thus,the bioactive patch expected to be applied in spinal dural repair with the good properties of withstanding high pressure,promoting defect closure and inhibiting postoperative infection.