New Biocomposite Electrospun Fiber/Alginate Hydrogel for Probiotic Bacteria Immobilization

Biosensing of arsenic by whole-cell bacterial bioreporter immobilized on polycaprolactone (PCL) electrospun fiber

In recent years, heavy metals derived from several anthropogenic sources have both direct and indirect detrimental effects on the health of the environment and living organisms. Whole-cell bioreporters (WCBs) that can be used to monitor the levels of heavy metals in drinking and natural spring waters are important. In this study, whole-cell arsenic bacterial bioreporters were immobilized using polycaprolactone (PCL) electrospun fibers as the support material. The aim is to determine the properties of this immobilized bioreporter system by evaluating its performance in arsenic detection. Within the scope of the study, different growth media and fiber immobilization times were tested to determine the parameters affecting the fluorescent signals emitted by the immobilized bioreporter system in the presence of two dominant forms of arsenic, namely arsenite (As(III)) and arsenate (As(V)). In addition, the sensitivity, selectivity, response time, and shelf-life of the developed bioreporter system were evaluated. As far as the literature is concerned, this is the first study to investigate the potential of using PCL-electrospun fiber-immobilized fluorescent bacterial bioreporter for arsenic detection. This study will open new avenues in environmental arsenic monitoring.

Characterization of modified rice straw biochar in immobilizing Bacillus subtilis 168 and evaluation on its role as a novel agent for zearalenone-removal delivery

Microbial remediation of environmental pollutants can be advanced by carrier based cells immobilization. Whereas the effects of microorganisms immobilized on biochar for removal of zearalenone (ZEN) still remain unknown. Herein, this work presented the characterization of rice straw biochar (RSB) around modification in immobilizing Bacillus subtilis 168 and the role in fighting ZEN in vitro. Specifically, 10% of RSB with pH 5 condition were optimal for bearing cells, where majority of cells loaded inside the pore and minority on surface with agglomeration or scattering status. Octadecyl trimethyl ammonium chloride-inclusion RSB showed better performances including over 93% of ZEN detoxification rate (32.48% in free cells), cells preservation, and stability of detoxification in simulated gastrointestinal environment. RSB treated with sulphuric acid made nutrients adsorption generally less than 6.5%. No residues of α-ZEL and α-ZAL were found in ZEN biotransformation process whether by free cells or composites. Mechanism discussion implied that predominant monolayer chemisorption by RSB and subsequent biodegradation by extracellular enzymes from microorganism involved in ZEN-removal process. Collectively, these findings contribute to provide an applying strategy for coordination of biochar and microorganisms as potentially mycotoxin detoxifying agent in agricultural feed bioremediation and environmental decontamination processes.

Electrospinning and Electrospraying: Emerging Techniques for Probiotic Stabilization and Application

Probiotics are beneficial for human health. However, they are vulnerable to adverse effects during processing, storage, and passage through the gastrointestinal tract, thus reducing their viability. The exploration of strategies for probiotic stabilization is essential for application and function. Electrospinning and electrospraying, two electrohydrodynamic techniques with simple, mild, and versatile characteristics, have recently attracted increased interest for encapsulating and immobilizing probiotics to improve their survivability under harsh conditions and promoting high-viability delivery in the gastrointestinal tract. This review begins with a more detailed classification of electrospinning and electrospraying, especially dry electrospraying and wet electrospraying. The feasibility of electrospinning and electrospraying in the construction of probiotic carriers, as well as the efficacy of various formulations on the stabilization and colonic delivery of probiotics, are then discussed. Meanwhile, the current application of electrospun and electrosprayed probiotic formulations is introduced. Finally, the existing limitations and future opportunities for electrohydrodynamic techniques in probiotic stabilization are proposed and analyzed. This work comprehensively explains how electrospinning and electrospraying are used to stabilize probiotics, which may aid in their development in probiotic therapy and nutrition.

Optimization of whole-cell bacterial bioreporter immobilization on electrospun cellulose acetate (CA) and polycaprolactone (PCL) fibers for arsenic detection

Arsenic contamination is a critical global problem, and its widespread environmental detection is becoming a prominent issue. Herein, electrospun fibers of cellulose acetate (CA) and polycaprolactone (PCL) were successfully fabricated and used as the support material for immobilization of arsenic-sensing bacterial bioreporter for the first time. To date, no attempt has been made to immobilize fluorescent whole-cell bioreporter cells on electrospun fibers for arsenic detection. CA and PCL electrospun fibers were fabricated via traditional electrospinning technique and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and contact angle meter. Following immobilization of the bacterial bioreporter cells, the immobilized bacteria were also characterized by viability assay using AlamarBlue. The effects of growth phase and cell concentration on the fluorescence response of fiber-immobilized arsenic bioreporters to arsenic were also investigated. After immobilization of arsenic bioreporters on 10 wt% PCL fiber, 91% of bacterial cells remained viable, while this value was 55.4% for cells immobilized on 12.5 wt% CA fiber. Bioreporter cells in the exponential growth phase were shown to be more sensitive to arsenic compared to aged cells. While both the electropsun PCL- and CA-immobilized bioreporters successfully detected 50 and 100 µg/L of arsenite (As (III)) concentrations, the PCL-immobilized bioreporter showed better fluorescence performance which should be investigated in future studies. This study helps to fill some gaps in the literature and demonstrates the potential for using electrospun fiber-immobilized arsenic whole-cell bioreporter for arsenic detection in water.

Synergistic action of laccase treatment and membrane filtration during removal of azo dyes in an enzymatic membrane reactor upgraded with electrospun fibers

Nowadays, the increasing amounts of dyes present in wastewaters and even water bodies is an emerging global problem. In this work we decided to fabricate new biosystems made of nanofiltration or ultrafiltration membranes combined with laccase entrapped between polystyrene electrospun fibers and apply them for decolorization of aqueous solutions of three azo dyes, C.I. Acid Yellow 23 (AY23), C.I. Direct Blue 71 (DB71) and C.I. Reactive Black 5 (RB5). Besides effective decolorization of the permeate stream, the biosystems also allowed removal of dyes from the retentate stream as a result of enzymatic action. The effect of pH and applied pressure on decolorization efficiencies was investigated, and pH 5 and pressure of 2 bar gave the highest removal efficiencies of 97% for AY23 and 100% for both DB71 and RB5 from permeate solutions while decolorization of retentate for RB5 reached 65% under these conditions. Almost 100% decolorization of all dyes was achieved after three consecutive enzyme membrane cycles. Decolorization was shown to be due to the synergistic action of membrane separation and bioconversion. The biocatalytic action also enabled significant reduction of permeate and retentate toxicity, which is one of the biggest environmental health issues for these types of streams.

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

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

Microencapsulating Alginate-Based Polymers for Probiotics Delivery Systems and Their Application

Probiotics exhibit many health benefits and a great potential for broad applications in pharmaceutical fields, such as prevention and treatment of gastrointestinal tract diseases (irritable bowel syndrome), prevention and therapy of allergies, certain anticancer effects, and immunomodulation. However, their applications are limited by the low viability and metabolic activity of the probiotics during processing, storage, and delivery in the digestive tract. To overcome the mentioned limitations, probiotic delivery systems have attracted much attention. This review focuses on alginate as a preferred polymer and presents recent advances in alginate-based polymers for probiotic delivery systems. We highlight several alginate-based delivery systems containing various types of probiotics and the physical and chemical modifications with chitosan, cellulose, starch, protein, fish gel, and many other materials to enhance their performance, of which the viability and protective mechanisms are discussed. Withal, various challenges in alginate-based polymers for probiotics delivery systems are traced out, and future directions, specifically on the use of nanomaterials as well as prebiotics, are delineated to further facilitate subsequent researchers in selecting more favorable materials and technology for probiotic delivery.