Evaluation of survival and release of encapsulated bacteria in ex vivo porcine gastrointestinal contents using a green fluorescent protein gene-labelled E. coli

Ultrasound-Driven On-Demand Transient Triboelectric Nanogenerator for Subcutaneous Antibacterial Activity

To prevent surgical site infection (SSI), which significantly increases the rate morbidity and mortality, eliminating microorganisms is prominent. Antimicrobial resistance is identified as a global health challenge. This work proposes a new strategy to eliminate microorganisms of deep tissue through electrical stimulation with an ultrasound (US)-driven implantable, biodegradable, and vibrant triboelectric nanogenerator (IBV-TENG). After a programmed lifetime, the IBV-TENG can be eliminated by provoking the on-demand device dissolution by controlling US intensity with no surgical removal of the device from the body. A voltage of ≈4 V and current of ≈22 µA generated from IBV-TENG under ultrasound in vitro, confirming inactivating ≈100% of Staphylococcus aureus and ≈99% of Escherichia coli. Furthermore, ex vivo results show that IBV-TENG implanted under porcine tissue successfully inactivates bacteria. This antibacterial technology is expected to be a countermeasure strategy against SSIs, increasing life expectancy and healthcare quality by preventing microorganisms of deep tissue.

Designing Natural Polymer-Based Capsules and Spheres for Biomedical Applications-A Review

Natural polymers, such as polysaccharides and polypeptides, are potential candidates to serve as carriers of biomedical cargo. Natural polymer-based carriers, having a core-shell structural configuration, offer ample scope for introducing multifunctional capabilities and enable the simultaneous encapsulation of cargo materials of different physical and chemical properties for their targeted delivery and sustained and stimuli-responsive release. On the other hand, carriers with a porous matrix structure offer larger surface area and lower density, in order to serve as potential platforms for cell culture and tissue regeneration. This review explores the designing of micro- and nano-metric core-shell capsules and porous spheres, based on various functions. Synthesis approaches, mechanisms of formation, general- and function-specific characteristics, challenges, and future perspectives are discussed. Recent advances in protein-based carriers with a porous matrix structure and different core-shell configurations are also presented in detail.

Development and Optimization of Attapulgite Clay Based Microencapsulation for Lactic Acid Bacteria by Response Surface Methodology

Lactic acid bacteria (LAB), screened and purified from the fermented yogurt, were microencapsulated in sodium alginate (SA) and attapulgite composite microcapsules by external gelation to increase their viability and stability. Surface characterization by scanning electron microscope clearly evidenced a high number of the LAB embedded in SA/attapulgite composite microcapsules than SA counterparts due to a more cohesive structure, and biocompatible microenvironment. SA/attapulgite and CaCl2/attapulgite composites analysis revealed a better embedding effect of attapulgite blend with SA solvent compared with attapulgite mixed with CaCl2. Influence of three major factors including SA, calcium chloride, and attapulgite concentration on LAB embedding rate were optimized by “single factor strategy” as well as response surface methodology (RSM). Optimal conditions of these factors obtained by RSM were SA (1.03 %), Attapulgite (0.28 %), and CaCl2 concentration (1.17 %). The related embedding rate was predicted as 87.1369 %, and the actual measured value was 91.24 % by experiments using the optimal conditions. In conclusion, the results revealed that LAB microencapsulation in the SA and attapulgite composite might display noteworthy protection against the gastrointestinal environment.

Application of whey protein micro-bead coatings for enhanced strength and probiotic protection during fruit juice storage and gastric incubation

CONTEXT

Coated whey protein micro-beads may improve probiotic protection and provide delayed cell-release mechanisms.

OBJECTIVE

Lactobacillus rhamnosus GG was encapsulated in whey protein micro-beads by droplet extrusion with coating via electrostatic deposition: primary-polysaccharide and secondary-whey protein.

MATERIALS AND METHODS

Storage studies were performed in cranberry and pomegranate juice (pH 2.4; 28 days; 4 and 25°C) followed by simulated ex vivo porcine gastric (pH 1.6) and intestinal (pH 6.6) digestion.

RESULTS AND DISCUSSION

After storage and simulated gastro-intestinal digestion, free cells, cells suspended in protein and cells encapsulated in alginate micro-beads, illustrated complete probiotic mortality, while coated micro-beads enhanced probiotic viability after juice storage (8.6 ± 0.1 log(10)CFUmL(-1)). Beads also showed significant binding of hydrophobic molecules. Coated micro-beads illustrated high gastric survival (9.5 ± 0.1 log(10)CFUmL(-1)) with 30 min delayed intestinal release relative to non-coated micro-beads.

CONCLUSIONS

Micro-bead coatings could be applied in delayed cell-release for targeted intestinal probiotic delivery.

Microencapsulation for the improved delivery of bioactive compounds into foods

The development of functional foods through the addition of bioactive compounds holds many technological challenges. Microencapsulation is a useful tool to improve the delivery of bioactive compounds into foods, particularly probiotics, minerals, vitamins, phytosterols, lutein, fatty acids, lycopene and antioxidants. Several microencapsulation technologies have been developed for use in the food industry and show promise for the production of functional foods. Moreover, these technologies could promote the successful delivery of bioactive ingredients to the gastrointestinal tract. Future research is likely to focus on aspects of delivery and the potential use of co-encapsulation methodologies, where two or more bioactive ingredients can be combined to have a synergistic effect.

Release studies of Lactobacillus casei strain Shirota from chitosan-coated alginate-starch microcapsules in ex vivo porcine gastrointestinal contents

AIMS

To investigate the release characteristics of Lactobacillus casei strain Shirota (LCS) from chitosan-coated alginate-starch (CCAS) capsule in different regions of ex vivo porcine gastrointestinal (GI) contents.

METHODS AND RESULTS

A 0.1 g of CCAS encapsulated bacteria (containing c. 10(8) CFU of LCS) were incubated in different sections of ex vivo porcine GI contents (10 ml) anaerobically at 37 degrees C. Samples were taken from different GI contents at different time intervals (up to 24 h) and estimated for the release of LCS from capsules. There was almost a complete release (1.1 x 10(8) CFU) of LCS from capsules within 8 h of incubation in ileal contents, while it took nearly 12 h to release the completely encapsulated bacteria in colon content under similar conditions. There was only a partial release of encapsulated LCS, incubated in duodenal and jejunal contents, while there was no significant (P > 0.05) release of encapsulated bacteria in gastric contents even after 24 h of incubation.

CONCLUSIONS

The capsules were able to release viable probiotic cells completely in ex vivo porcine ileal and colon contents.

SIGNIFICANCE AND IMPACT OF THE STUDY

CCAS capsule can be an effective way of protecting probiotic bacteria from adverse gastric conditions and delivering viable bacteria to the host intestinal systems.