Tuning Alginate Microparticle Size via Atomization of Non-Newtonian Fluids

Engineering Alginate-Based Dry Powder Microparticles to a Size Suitable for the Direct Pulmonary Delivery of Antibiotics

The inhaled route is regarded as one of the most promising strategies as a treatment against pulmonary infections. However, the delivery of drugs in a dry powder form remains challenging. In this work, we have used alginate to form microparticles containing an antibiotic model (colistin sulfate). The alginate microparticles were generated by atomization technique, and they were characterized by antimicrobial in vitro studies against Pseudomonas aeruginosa. Optimization of different parameters allowed us to obtain microparticles as a dry powder with a mean size (Feret diameter) of 4.45 ± 1.40 µm and drug loading of 8.5 ± 1.50%. The process developed was able to concentrate most of the colistin deposits on the surface of the microparticles, which could be observed by SEM and a Dual-Beam microscope. This produces a fast in vitro release of the drug, with a 100% release achieved in 4 h. Physicochemical characterization using the FTIR, EDX and PXRD techniques revealed information about the change that occurs from the amorphous to a crystalline form of colistin. Finally, the cytotoxicity of microparticles was tested using lung cell lines (A549 and Calu-3). Results of the study showed that alginate microparticles were able to inhibit bacterial growth while displaying non-toxicity toward lung cells.

Continuous production of cellulose microbeads by rotary jet atomization

The replacement of plastic microbeads with biodegradable alternatives is essential due to the environmental persistence of plastics and their accumulation within the human food chain.

HYPOTHESIS

Cellulose microbeads could be such alternative, but their production is hindered by the high viscosity of cellulose solutions. It is expected that this viscosity can be harnessed to induce filament thinning of jets of cellulose solutions to create droplets with diameters within the micrometre range, which can then be converted to solid cellulose microbeads via phase inversion.

EXPERIMENTS

A 3D printed rotating multi-nozzle system was used to generate jets of cellulose dissolved in solutions of [EMIm][OAc] and DMSO. The jets were subject to Rayleigh breakup to generate droplets which were captured in an ethanol anti-solvent bath, initiating phase-inversion, and resulting in regeneration of the cellulose into beads.

FINDINGS

Control of both process (e.g. nozzle dimensions) and operational (e.g. rotational speed and pressure) parameters has allowed suppression of both satellite droplets generation and secondary droplet break-up, and tuning of the filament thinning process. This resulted in the continuous fabrication of cellulose microbeads in the size range 40-500 μm with narrow size distributions. This method can produce beads in size ranges not attainable by existing technologies.

Preparation of Curcumin Hydrogel Beads for the Development of Functional Kulfi: A Tailoring Delivery System

Curcumin has been demonstrated to have biological activities and its fortification in food products is an important strategy to deliver bioactive ingredients at target sites. However, studies have documented a curcumin low bioavailability and low intake. Hence, combining functional ingredients with food should be needed to prevent widespread nutrient intake shortfalls and associated deficiencies. Thus, curcumin was encapsulated in calcium-alginate and their characteristics as well as in vitro release behavior of curcumin hydrogel beads (CHBs) was studied. Moreover, CHBs were fortified in development of functional Kulfi and their quality characteristics were studied. The encapsulation efficiency was up to 95.04%, indicating that most of the curcumin was entrapped. FTIR shifts in the bands were due to the replacement of sodium ions to the calcium ions. In vitro release (%) for CHBs was found to be 67.15% after 2 h, which increased slightly up to 67.88% after 4 h. The average swelling index of CHBs was found to be 10.21 to 37.92 from 2 to 12 h in PBS (pH 7.40). Control and Kulfi fortified with CHBs showed no significant difference (p > 0.05) in colour (L = 73.03 and 75.88) and the melting rate (0.88 mL/min and 0.63 mL/min), respectively. Standard plate count was reduced in the Kulfi fortified with CHBs (13.77 × 10⁴ CFU/mL) with high sensory score for overall acceptability (8.56) compared to the control (154.70 × 10⁴ CFU/mL). These findings suggested the feasibility of developing CHBs to mask the bitterness, enhance the solubility, and increase the bioavailability in gastrointestinal conditions. Additionally, Kulfi could be a suitable dairy delivery system for curcumin bioactive compounds.