One-Step Biosynthesis of Soft Magnetic Bacterial Cellulose Spheres with Localized Nanoparticle Functionalization

Abstract

Actuated structures are becoming relevant in medical fields; however, they call for flexible/soft-base materials that comply with biological tissues and can be synthesized in simple fabrication steps. In this work, we extend the palette of techniques to afford soft, actuable spherical structures taking advantage of the biosynthesis process of bacterial cellulose. Bacterial cellulose spheres (BCS) with localized magnetic nanoparticles (NPs) have been biosynthesized using two different one-pot processes: in agitation and on hydrophobic surface-supported static culture, achieving core-shell or hollow spheres, respectively. Magnetic actuability is conferred by superparamagnetic iron oxide NPs (SPIONs), and their location within the structure was finely tuned with high precision. The size, structure, flexibility and magnetic response of the spheres have been characterized. In addition, the versatility of the methodology allows us to produce actuated spherical structures adding other NPs (Au and Pt) in specific locations, creating Janus structures. The combination of Pt NPs and SPIONs provides moving composite structures driven both by a magnetic field and a H2O2 oxidation reaction. Janus Pt/SPIONs increased by five times the directionality and movement of these structures in comparison to the controls.

Microencapsulation of Lacticaseibacillus rhamnosus GG for Oral Delivery of Bovine Lactoferrin: Study of Encapsulation Stability, Cell Viability, and Drug Release

“…Moreover, they are used as food additives because of their ability to serve as a barrier against pathogen invasion, alleviate antibiotic-associated diarrhea, and stimulate immunomodulation [ 2 ]. Although oral delivery is a simple, convenient, and low-cost approach with a minimal risk of infection [ 3 ], the orally delivered protein-based drugs suffer from a low level of bioavailability, poor absorption, internalization through the GIT epithelium, and high hydrolytic and enzymatic [ 4 ] degradation by the GIT fluids [ 5 , 6 ]. At the same time, the oral administration of probiotics is a major challenge considering the risks of systemic infection, replacement of the human microbiota, gene transfer, deleterious metabolic activities, low survival in the GIT, provoking the immune response, etc.…”

“…Among the different techniques for cell surface modification, including layer-by-layer [ 12 ], extrusion [ 13 ], genetic engineering [ 14 ], adsorption [ 15 ], biomineralization [ 16 ], direct single-step magnetization [ 4 ], etc., microencapsulation has been widely employed in the food industry for enhancing the survival rates of probiotics [ 17 ]. Microencapsulation of probiotics not only provides protection to the bacterial cells, but also assists the probiotic-specific delivery [ 18 ].…”

Highly Aligned Bacterial Nanocellulose Films Obtained During Static Biosynthesis in a Reproducible and Straightforward Approach

“…Figure S5 shows images of the methodology to obtain A‐BNC films in large vessels (30 cm). Finally, instead of using the typical streak plate (or zig–zag) method to obtain the initial agar substrate with bacterial colonies, [ 50 ] we grew confluent agar Petri dishes to maximize the number of bacteria per surface to obtain high‐density A‐BNC fiber films. This strategy allowed us to obtain A‐BNC films with a thickness of ≈200 µm in wet.…”

“…After separating the films, the cleaning process took place separately. BNC films were soaked and stirred with a magnetic stirring plate in the following steps [ 46 , 50 ] : i) 1:1 Ethanol: Milli‐Q water solution for 10 min, ii) 40 min in boiling Milli‐Q water, and iii) two periods of 20 min in 0.1 m NaOH (Sigma‐Aldrich) aqueous solution. Finally, the BNC films were rinsed with Milli‐Q water until reaching neutral pH, autoclaved at 121 °C for 20 min and stored suspended in water in glass vials at room temperature.…”