Stability of 2-D colloidal particle aggregates held against flow stress in an ultrasound trap

Synthesis and characterization of nanozeolite from (agro)industrial waste for application in heterogeneous photocatalysis

The pollution of wastewater with dyes has become a serious environmental problem around the world. In this context, the work aims to synthesize and characterize a supported nanocatalyst (NZ-180) from rice husk (RH) and alum sludge (AS) incorporating silver (AgNPs@NZ-180) and titanium nanoparticles (TiNPs@NZ-180) for Rhodamine B (RhB) dye degradation, under UV and visible irradiation. Central rotatable composite design (CRCD) was used to determine ideal conditions, using nanocatalyst and dye concentration such as input variables and degradation percentage like response variable. Samples were characterized by XRD, SEM-EDS, N₂ porosimetry, DLS, and zeta potential analyses. TiNPs@NZ-180 showed the best photocatalytic activity (62.62 and 50.82% under UV and visible irradiation, respectively). Specific surface area has increased from 35.90 to 418.90 m² g^-1 for NZ-180 and TiNPs@NZ-180, respectively. Photocatalytic performance of TiNPs@NZ-180 has reduced to 8 and 10% after 5 cycles under UV and visible light irradiation. Ideal conditions found by CRCD were 2.75 g L^-1 and 20 mg L^-1 for nanocatalyst and RhB concentrations, respectively. Therefore, (agro)industrial waste present such an alternative material for application in the removal of wastewater with dyes, which helps in the reduction of the impact of chemicals/pollutants on human and animal health.

Generation of functional hepatocyte 3D discoids in an acoustofluidic bioreactor

Ultrasonic standing wave systems have previously been used for the generation of 3D constructs for a range of cell types. In the present study, we cultured cells from the human hepatoma Huh7 cell line in a Bulk Acoustic Wave field and studied their viability, their functions, and their response to the anti-cancer drug, 5 Fluorouracil (5FU). We found that cells grown in the acoustofluidic bioreactor (AFB) expressed no reduction in viability up to 6 h of exposure compared to those cultured in a conventional 2D system. In addition, constructs created in the AFB and subsequently cultured outside of it had improved functionality including higher albumin and urea production than 2D or pellet cultures. The viability of Huh7 cells grown in the ultrasound field to 5FU anti-cancer drug was comparable to that of cells cultured in the 2D system, showing rapid diffusion into the aggregate core. We have shown that AFB formed 3D cell constructs have improved functionality over the conventional 2D monolayer and could be a promising model for anti-cancer drug testing.

Single-Beam Acoustic Trapping of Red Blood Cells and Polystyrene Microspheres in Flowing Red Blood Cell Saline and Plasma Suspensions

Single-beam acoustic tweezers (SBATs) represent a new technology for particle and cell trapping. The advantages of SBATs are their deep penetration into tissues, reduction of tissue damage and ease of application to in vivo studies. The use of these tools for applications in drug delivery in vivo must meet the following conditions: large penetration depth, strong trapping force and tissue safety. A reasonable penetration depth for SBATs in the development of in vivo applications was established in a previous study conducted in water with zero velocity. However, capturing objects in flowing fluid can provide more meaningful results. In this study, we investigated the capability of SBATs to trap red blood cells (RBCs) and polystyrene microspheres in flowing RBC suspensions. Two different types of RBC suspension were prepared in this work: an RBC phosphate-buffered saline (PBS) suspension and an RBC plasma suspension. The results indicated that SBATs successfully trapped RBCs and polystyrene microspheres in a flowing RBC PBS suspension with an average steady velocity of 1.6 cm/s in a 2-mm-diameter polyimide. Furthermore, SBATs were found able to trap RBCs in a flowing RBC PBS suspension at speeds as high as 7.9 cm/s in a polyimide tube, which is higher than the velocity in capillaries (0.03 cm/s) and approaches the velocity in arterioles and venules. Moreover, the results also indicated that polystyrene microspheres can be trapped in an RBC plasma suspension, where aggregation is observed. This work represents a step forward in using this tool in actual in vivo experimentation.

Acoustically enriching, large-depth aquatic sampler

In marine biology, it is useful to collect water samples when exploring the distribution and diversity of microbial communities in underwater environments. In order to provide, e.g., a miniaturized submersible explorer with the capability of collecting microorganisms, a compact sample enrichment system has been developed. The sampler is 30 mm long, 15 mm wide, and just a few millimetres thick. Integrated in a multilayer steel, polyimide and glass construction is a microfluidic channel with piezoelectric transducers, where microorganism and particle samples are collected and enriched, using acoustic radiation forces for gentle and labelless trapping. High-pressure, latchable valves, using paraffin as the actuation material, at each end of the microfluidic channel keep the collected sample pristine. A funnel structure raised above the surface of the device directs water into the microfluidic channel as the vehicle propels itself or when there is a flow across its hull. The valves proved leak proof to a pressure of 2.1 MPa for 19 hours and momentary pressures of 12.5 MPa, corresponding to an ocean depth of more than 1200 metres. By reactivating the latching mechanism, small leakages through the valves could be remedied, which could thus increase the leak-less operational time. Fluorescent particles, 1.9 μm in diameter, were successfully trapped in the microfluidic channel at flow rates up to 15 μl min(-1), corresponding to an 18.5 cm s(-1) external flow rate of the sampler. In addition, liquid-suspended GFP-marked yeast cells were successfully trapped.

Low-frequency ultrasound in biotechnology: state of the art

The use of low-frequency (10-60 kHz) ultrasound for enhancement of various biotechnological processes has received increased attention over the last decade as a rapid and reagentless method. Recent breakthroughs in sonochemistry have made the ultrasound irradiation procedure more feasible for a broader range of applications. By varying the sonication parameters, various physical, chemical and biological effects can be achieved that can enhance the target processes in accordance with the applied conditions. However, the conditions that have provided beneficial effects of ultrasound on bioprocesses are case-specific and are therefore not widely available in the literature. This review summarizes the current state of the art in areas where sonochemistry could be successfully combined with biotechnology with the aim of enhancing the efficiency of bioprocesses, including biofuel production, bioprocess monitoring, enzyme biocatalysts, biosensors and biosludge treatment.