Mixed Molecular Weight Research Articles

Ultrasound-responsive hydrogel microcapsules for on-demand drug release

Hydrogel-based implantable systems offer viable solutions for localized drug delivery but often lack the ability to easily achieve on-demand actuation or real-time tuning of release kinetics in response to physiological changes. Here, we present a hydrogel microcapsules produced using two-phase microfluidics that can release drugs on demand as triggered by focused ultrasound (FUS). The biphasic microcapsules consist of an outer phase of mixed molecular weight (MW) poly(ethylene glycol) diacrylate that mitigates premature payload release and an inner phase of high MW dextran with payload that breaks down in response to FUS. Compound release from microcapsules could be triggered as desired; 0.4 μg of payload was released across 16 on-demand steps over days. We detected broadband acoustic signals amidst low heating, suggesting inertial cavitation as a key mechanism for payload release. Overall, FUS-responsive microcapsules are a biocompatible and wirelessly triggerable structure for on-demand drug delivery over days to weeks.

Ultrasound‐Responsive Aqueous Two‐Phase Microcapsules for On‐Demand Drug Release

AbstractTraditional implanted drug delivery systems cannot easily change their release profile in real time to respond to physiological changes. Here we present a microfluidic aqueous two‐phase system to generate microcapsules that can release drugs on demand as triggered by focused ultrasound (FUS). The biphasic microcapsules are made of hydrogels with an outer phase of mixed molecular weight (MW) poly(ethylene glycol) diacrylate that mitigates premature payload release and an inner phase of high MW dextran with payload that breaks down in response to FUS. Compound release from microcapsules could be triggered as desired; 0.4 μg of payload was released across 16 on‐demand steps over days. We detected broadband acoustic signals amidst low heating, suggesting inertial cavitation as a key mechanism for payload release. Overall, FUS‐responsive microcapsules are a biocompatible and wirelessly triggerable structure for on‐demand drug delivery over days to weeks.

Ultrasound-Responsive Aqueous Two-Phase Microcapsules for On-Demand Drug Release.

Traditional implanted drug delivery systems cannot easily change their release profile in real time to respond to physiological changes. Here we present a microfluidic aqueous two-phase system to generate microcapsules that can release drugs on demand as triggered by focused ultrasound (FUS). The biphasic microcapsules are made of hydrogels with an outer phase of mixed molecular weight (MW) poly(ethylene glycol) diacrylate that mitigates premature payload release and an inner phase of high MW dextran with payload that breaks down in response to FUS. Compound release from microcapsules could be triggered as desired; 0.4 μg of payload was released across 16 on-demand steps over days. We detected broadband acoustic signals amidst low heating, suggesting inertial cavitation as a key mechanism for payload release. Overall, FUS-responsive microcapsules are a biocompatible and wirelessly triggerable structure for on-demand drug delivery over days to weeks.

Natural flocculants from fresh and saline wastewater: Comparative properties and flocculation performances

Natural flocculants, due to their eco-friendliness, have gained increasing attention for (waste) water treatment and are promising alternatives to oil-based synthetic flocculants. We systematically investigated simultaneous industrial wastewater treatment with the production of microbial extracellular polymeric substances (EPS) as natural flocculants. EPS were produced in two membrane bioreactors, respectively treating fresh and saline synthetic wastewater from biodiesel and (bio)ethanol industries. From each reactor, soluble and bound EPS fractions were extracted, purified and characterised for their functionalities, molecular weights and charge densities using Fourier transform infrared (FTIR), size exclusion chromatography and colloid titration, respectively. High removal of chemical oxygen demand (COD) was achieved in both reactors (93–95%), with 5.8–7.6% of the inlet COD recovered as EPS. FTIR spectroscopy reveals these EPS as a mixture of proteins and polysaccharides, possessing carboxyl, hydroxyl and amine groups. These functional groups, which provided a net anionic charge density (1.5–2.9 meq/g at neutral pH), coupled with EPS mixed molecular weight (MW) distribution: high (>1000 kDa), medium (1000–100 kDa) and low (<100 kDa) MW fractions, make them promising flocculants. Extracted EPS showed good flocculation of non-saline kaolin suspension (74–89% turbidity reduction) and excellent flocculation of saline kaolin suspension (88–97%), performances comparable to anionic polyacrylamide. The results show the possibility for wastewater treatment plants to combine wastewater treatment with the production of valuable flocculants.

Textural and Rheological Properties of Oat Beta-Glucan Gels with Varying Molecular Weight Composition

The impact of oat β-glucan concentration and molecular weight (MW) on gel properties was investigated. Mixed MW gels/viscous solutions at 3, 4, and 5% β-glucan with high molecular weight (HMW):low molecular weight (LMW) ratios of 0:100, 25:75, 50:50, 75:25, and 100:0 were evaluated. The 100:0 and 50:50 gels had the lowest tan δ values. The 50:50 gels had the highest storage moduli (G'), whereas 100:0 solutions did not gel. Peak melting temperature (TP) was highest for 0:100 gels and decreased with the addition of HMW β-glucan. Hardness, at 40% compression, increased with concentration, and 25:75 and 50:50 gels were hardest at each concentration. Ordered microstructure, apparent in 0:100 gels, diminished with HMW β-glucan addition. Glucose addition resulted in lower tan δ values and firmer, harder gels compared to gels without glucose. Thus, the textural properties and melting profiles of β-glucan gels can be manipulated by adjusting the ratios of molecular weight fractions or addition of sugar for different applications.