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Graphical abstract Highlights • Drug-loaded Ca-Alg particles are fabricated on the superhydrophobic substrate. • The controllable fabrication of Ca-Alg particles can be easily achieved. • The drug encapsulation efficiencies are measured to be over 88%. • The drug exhibits obvious pH responsive release. Abstract Drug delivery systems with high drug encapsulation efficiency and controlled release are of great importance in biomedical fields. Herein, we report an ingenious approach inspired from the lotus leaf possessing the ability of strong repellency to water, which enables the rapid fabrication of drug-loaded calcium alginate (Ca-Alg) particles with high drug encapsulation efficiency and controlled drug delivery. The design is achieved by introducing aqueous droplets containing the mixture of dilute sodium alginate solution, dilute calcium chloride solution, and drug onto the superhydrophobic substrate. Due to water evaporation both the concentration of sodium alginate and calcium chloride within the droplets will gradually increase, and the ionic crosslinking reaction of sodium alginate with Ca2+ is further occurred to form the drug-embedded Ca-Alg hydrogel particles. The results indicate that the controllable fabrication of Ca-Alg particles can be easily achieved on the superhydrophobic surface, and the swelling behavior can be tuned by the pH of the buffer solution. Importantly, the drug encapsulation efficiencies are measured to be over 88% and the drug exhibits obvious pH responsive release. Findings from this study are expected to contribute to the rational design of drug delivery systems with high drug encapsulation efficiency and controlled release for pharmaceutic science and tissue engineering. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Increased electrostatic attraction enhanced the adsorption efficiency of solute by Ca-alginate. • Diffusion was investigated in Ca-alginate hydrogel as a function of solute charge. • Negatively charged Ca-alginate improved the degradation rate of positively charged pollutant. • Beads charge had a significant impact on the degradation of positively charged pollutant. • Dispersity of NZVI particles in beads influenced the degradation efficiency of malachite green. Abstract The adsorption capacity of calcium alginate (Ca-alginate) beads was evaluated by measuring the removal of three organic compounds with different charges (malachite green, p -chlophenol and methyl orange). The diffusion was investigated in Ca-alginate hydrogel as a function of solute charge. It was found that an increased electrostatic attraction between the hydrogel and solute would improve the mobility of solute and hence enhance its adsorption efficiency. The degradation kinetics of charged pollutants by Ca-alginate with NZVI entrapped (NZVI-alginate) beads was compared to that of bare NZVI and the data followed a pseudo-first-order kinetic model. Negatively charged Ca-alginate hydrogel strongly adsorbed positively charged pollutant, which led to an enhancement in degradation rate. However, the degradation efficiency of neutral and negatively charged pollutants by NZVI-alginate was comparable with that by bare NZVI. Thus, the degradation ability of NZVI-alginate was related with the diffusion and adsorption behavior of solutes in Ca-alginate hydrogel. The experimental results showed that the free calcium ions containing in Ca-alginate had a significant impact on the adsorption and degradation behaviors of positively charged pollutant, but those of neutral and negatively charged pollutants were only moderately affected. With the dispersity of NZVI particles in beads (1:1–1:4, w/w) increasing, the degradation efficiency of malachite green was improved, whereas further increase of NZVI dispersity (1:6, w/w) brought about a depressed degradation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cancer cells are easily encapsulated in 3D alginate hydrogels of reproducible size. • Crosslinked alginate has dosimetric properties comparable to tissue phantom. • Larger hydrogels possess a radiobiologically and clinically relevant hypoxic core. • Hydrogels can be used for hyperpolarized MRS and extracellular flux analysis. Abstract The purpose of this study is to demonstrate calcium alginate hydrogels as a system for in vitro radiobiological and metabolic studies of cancer cells. Previous studies have established calcium alginate as a versatile three-dimensional (3D) culturing system capable of generating areas of oxygen heterogeneity and modeling metabolic changes in vitro. Here, through dosimetry, clonogenic and viability assays, and pimonidazole staining, we demonstrate that alginate can model radiobiological responses that monolayer cultures do not simulate. Notably, alginate hydrogels with radii greater than 500 μm demonstrate hypoxic cores, while smaller hydrogels do not. The size of this hypoxic region correlates with hydrogel size and improved cell survival following radiation therapy. Hydrogels can also be utilized in hyperpolarized magnetic resonance spectroscopy and extracellular flux analysis. Alginate therefore offers a reproducible, consistent, and low-cost means for 3D culture of cancer cells for radiobiological studies that simulates important in vivo parameters such as regional hypoxia and enables long-term culturing and in vitro metabolic studies. [ABSTRACT FROM AUTHOR]

The indiscriminate use of antibiotics and the emergence of resistant microorganisms have become a major challenge for the food industry. The purpose of this work was to microencapsulate the bacteriophage UFV-AREG1 in a calcium alginate matrix using microfluidic devices and to study the viability and efficiency of retention. The microcapsules were added to gel of propylene glycol for use as an antimicrobial in the food industry. The technique showed the number of the phage encapsulation, yielding drops with an average 100–250 μm of diameter, 82.1 ± 2% retention efficiency and stability in the gel matrix for 21 days. The gel added to the microencapsulated phage showed efficiency (not detectable on the surface) in reducing bacterial contamination on the surface at a similar level to antimicrobial chemicals (alcohol 70%). Therefore, it was possible to microencapsulate bacteriophages in alginate-Ca and apply the microcapsules in gels for use as sanitizers in the food industry. [ABSTRACT FROM AUTHOR]

Entrapment of enzymes in calcium alginate beads is a popular enzyme immobilization method. However, leaching of immobilized enzymes from the alginate beads is a common problem because enzyme molecules are much smaller than the pore size of alginate beads (∼200 nm). To address this issue, we employ a millifluidic reactor to prepare cross-linked cellulase aggregate (XCA) colloids with a uniform size (∼300 nm). Subsequently, these colloids are immobilized in calcium alginate beads as biocatalysts to hydrolyze cellulose substrates. By using fluorescent microscopy, we conclude that the immobilized XCA colloids distribute uniformly inside the beads and do not leach out from the beads after long-term incubation. Meanwhile, the pore size of the alginate beads is big enough for the cellulose substrates and fibers to diffuse into the beads for hydrolysis. For example, palm oil fiber and microcrystalline cellulose can be hydrolyzed within 48 h and release reducing sugar concentrations up to 2.48 ± 0.08 g/l and 4.99 ± 0.09 g/l, respectively. Moreover, after 10 cycles of hydrolysis, 96.4% of the XCA colloids remain inside the alginate beads and retain 67% of the original activity. In contrast, free cellulase immobilized in the alginate beads loses its activity completely after 10 cycles. The strategy can also be used to prepare other types of cross-linked enzyme aggregates with high uniformity. [ABSTRACT FROM AUTHOR]

Wound healing is a complex physiological process involving four coordinated stages, including hemostasis, anti-inflammatory, repair, and epithelial formation. Herein, multifunctional core-shell alkylated chitosan/calcium alginate microfibers are fabricated as a novel strategy for promoting wound healing by contributing to each four stages in the entire healing process. Taking advantages of the microfluidic technology, the core-shell microfibers can be generated in a continuous and convenient manner through the interfacial assembly between alkylated chitosan and Na-alginate, as well as the simultaneous crosslink between calcium and the alginate. Generated microfibers possess unique internal structure which can effectively promote the absorption of blood and exudate produced during trauma. Moreover, the dodecyl carbon chain and abundant amino groups of alkylated chitosan provide microfibers with excellent hemostatic and antibacterial properties, which can repair acute hemorrhage and destroy bacteria rapidly. Further, the chronic wound healing process of a skin injury model can be significantly promoted by applying the fabricated microfibers. With these sequential functions to guide the whole-stage wound healing, the presented multifunctional core-shell microfibers create a versatile and robust paradigm for comprehensive wound treatment. [Display omitted] • Microfluidics is applied for fabricating multifunctional core-shell microfibers. • The microfibers show excellent hemostatic and antibacterial capacities. • Chronic wound healing can be significantly improved by the microfibers. • The sequential functions of microfibers can promote the whole-stage wound healing. [ABSTRACT FROM AUTHOR]

In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca 2+ released from HAp by decreasing pH with slow hydrolysis of d -gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications. [ABSTRACT FROM AUTHOR]

A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205–496% and 417–586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering. [ABSTRACT FROM AUTHOR]

In this study, we develop a nano-micro alternating multilayer scaffold for bone tissue engineering by incorporation of monodispersed calcium alginate microbeads into electrospun polymer nanofibers. Both rat bone marrow mesenchymal stem cells (rBMSCs) and bone morphogenetic protein-2 (BMP-2) are simultaneously loaded into the microbeads, which are generated from a microfluidic device. The layer number of the scaffold can be readily controlled by alternately repeating the electrospinning and the microfluidic processes. Alkaline phosphatase (ALP) activity and Alizarin Red S staining results demonstrate that this rBMSCs and BMP-2 loaded nano-micro alternating multilayer scaffold presents an outstanding osteogenic effect in vitro . Histological and immunohistochemical assessments further reveal that this multilayer scaffold has a significant capability of ectopic bone formation in vivo , enabling this newly developed scaffold to be suitable for wide applications in tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: Biosynthetic hydrogels of poly vinyl alcohol–calcium alginate were prepared as semi (semi-IPN hydrogel, PAH) and full interpenetrating polymeric network (IPN hydrogel, PAHG) for tissue engineering of cardiac tissue. The biological response of these hydrogels was studied. The IPN hydrogel exhibits amphiphilic nature and moderate equilibrium water content. The IPN hydrogel inherits the water as structured one along with more free water. The IPN hydrogel has adequate mechanical strength and fatigue life and stability in physiological media over the semi-IPN hydrogel. The structured water along with more free water in IPN hydrogel promotes blood compatibility, cell adhesion and proliferation and maintains three dimensional growths of L929 fibroblast and H9C2 cardiomyoblasts. IPN hydrogel maintain long term cell viability and infiltration with exchange of nutrients in the interstices of the hydrogel. The IPN hydrogel, PAHG is a promising material for engineering cardiac tissue. [Copyright &y& Elsevier]

Abstract: Monosized sodium alginate microdroplets are prepared using a flow-focusing microdevice by adjusting the flow rate of the continuous phase (soybean oil) and the dispersed phase (sodium alginate solution). The gelation process of the semi-product, sodium alginate microdroplets, occurs outside the channel in a calcium chloride solution to form tadpole-shaped calcium alginate microparticles. The microparticles prepared are in the range of 100–250μm in diameter, depending on the experimental conditions. The shape, size and size distribution of these calcium alginate microparticles depend strongly on the calcium solution concentration and the stirring mode. The shaping mechanism of the microparticles and the impact of the experimental conditions on particle shape and size are investigated. [Copyright &y& Elsevier]

Abstract: In primary or metastatic lung cancer, administration of chemotherapeutic agents via inhalation could increase exposure of lung tumor to the drug, while minimizing systemic side effects. In addition, mucosal drug delivery system may reduce the toxicity and increase the site specific efficacy of drugs. Sodium alginate is a biodegradable, biocompatible and mucoadhesive polymer which is used for site specific drug delivery to mucosal tissues. At the present study alginate microparticles were fabricated by an emulsification technique and characterized. Selection of appropriate parameters enabled the preparation of microparticles with a mean volume diameter of 3±0.7μm, mass median aerodynamic diameter of 5.9±0.33μm, fine particle fraction of 13.9±0.57% and encapsulation efficiency of 61±4%. The in vitro release profile showed a slower release rate for microparticles compare to pure paclitaxel. Physiochemical characterization of paclitaxel via FT-IR, DSC and XRD techniques revealed information of solid state of paclitaxel loaded microparticles. The in vitro cytotoxicity activity of paclitaxel loaded microparticles was assessed using human non-small cell lung cancer cell lines (A549 and Calu-6). Results showed that exposure of cells to pure paclitaxel and paclitaxel loaded microparticles effectively inhibited the growth of A549 and Calu-6 cells similarly in a concentration- and time-dependent manner. [Copyright &y& Elsevier]

[Display omitted] • PPy/Ca-alginate/Gel microsphere contained temperature-sensitive gelatin and sunlight-sensitive PPy. • PPy can convert the absorbed light into heat energy and cause the structural transition of gelatin. • Helix-coil structure transition of gelatin could promote the release of carbendazim. • PPy/Ca-alginate/Gel has great potential in agriculture for agrochemicals release. Responsive controlled-release systems can not only improve the efficiency of agrochemical utilization but also increase crop yield and reduce environmental pollution caused by excessive use of agrochemicals. In this paper, the helix-coil structural transition of gelatin was adopted to construct a novel stimuli-responsive controlled-release system called polypyrrole/Ca-alginate/gelatin (PPy/Ca-alginate/Gel). In PPy/Ca-alginate/Gel, Ca-alginate and gelatin form a semi-interpenetrating network in which uncross-linked gelatin can undergo a free helix-coil structural transition due to the photothermal effect of PPy. The structural transition of gelatin will lead to changes in the functional groups and microstructure of semi-interpenetrating hydrogels and furthermore achieve the release of template agrochemical molecules embedded in hydrogels. By using carbendazim as a template molecule, the photothermal conversion and controlled release of PPy/Ca-alginate/Gel were systematically studied. After 600 s of light irradiation, its temperature could be increased by 17 ℃. The release of carbendazim in microspheres reached 91.8 % after 8 h of light irradiation, while it was only 13.3 % in the dark. The results indicated that PPy/Ca-alginate/Gel have excellent controlled-release and sustained-release properties and broad application potential in agriculture. [ABSTRACT FROM AUTHOR]

• Biocatalyst was prepared by assembling co-immobilization of laccase and mediator. • Acridine of 30 mg/L in water could be completely degraded by biocatalyst. • Possible reaction mechanism and degradation pathways of acridine were proposed. • The biocatalyst can be conveniently recovered with considerable reusability. A heterogeneous bead-shaped biocatalyst was prepared by assembling co-immobilization of encapsulating mediator 2,2′-Azino-bis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) into the functionalized calcium alginate composite beads by grafting glycidyl methacrylate and dopamine and then immobilizing laccase covalently onto beads. The enzyme-catalyzed degradation for acridine in water was systematically studied for the first time, and it was found that the co-immobilized laccase-mediator system has excellent capability to degrade acridine in water. Treating 30 mg/L acridine aqueous solution for 8 h with the biocatalyst, the degradation rate of acridine reached 100 %. In contrast, the degradation of acridine by free laccase under the same treatment conditions was low and difficult to observe. Its outstanding catalytic activity could be attributed to the effective assembling co-immobilization of laccase and the mediator so that the catalytic activity of the enzyme and the synergistic promoting action of the mediator have been given full play in the process of acridine degradation. The beaded biocatalyst about 3 mm in diameter could be easily recovered and reused several times without obvious deterioration in catalytic activity. Furthermore, according to the test results of electron paramagnetic resonance and the identified intermediates, the possible biocatalytic mechanism and reaction pathways for acridine degradation have been proposed. [ABSTRACT FROM AUTHOR]