Biosensor for ATP detection via aptamer-modified PDA@POSS nanoparticles synthesized in a microfluidic reactor.

This study introduces aptamer-functionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticles for adenosine triphosphate (ATP) detection where the POSS nanoparticles were synthesized in a one-step, continuous flow microfluidic reactor utilizing thermal polymerization. A microemulsion containing POSS monomers was generated in the microfluidic reactor which was designed to prevent clogging by using a continuous oil flow around the emulsion during thermal polymerization. Surfaces of POSS nanoparticles were biomimetically modified by polydopamine. The aptamer sequence for ATP was successfully attached to POSS nanoparticles. The aptamer-modified POSS nanoparticles were tested for affinity-based biosensor applications using ATP as a model molecule. The nanoparticles were able to capture ATP molecules successfully with an affinity constant of 46.5 [Formula: see text]M. Based on this result, it was shown, for the first time, that microfluidic synthesis of POSS nanoparticles can be utilized in designing aptamer-functionalized nanosystems for biosensor applications. The integration of POSS in biosensing technologies not only exemplifies the versatility and efficacy of these nanoparticles but also marks a significant contribution to the field of biorecognition and sample preparation.

Antibacterial properties and osteoblast interactions of microfluidically synthesized chitosan - SPION composite nanoparticles.

In this research, a multi-step microfluidic reactor was used to fabricate chitosan - superparamagnetic iron oxide composite nanoparticles (Ch - SPIONs), where composite formation using chitosan was aimed to provide antibacterial property and nanoparticle stability for magnetic resonance imaging (MRI). Monodispersed Ch - SPIONs had an average particle size of 8.8 ± 1.2 nm with a magnetization value of 32.0 emu/g. Ch - SPIONs could be used as an MRI contrast agent by shortening T2 relaxation parameter of the surrounding environment, as measured on a 3 T MRI scanner. In addition, Ch - SPIONs with concentrations less than 1 g/L promoted bone cell (osteoblast) viability up to 7 days of culture in vitro in the presence of 0.4 T external static magnetic field. These nanoparticles were also tested against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), which are dangerous pathogens that cause infection in tissues and biomedical devices. Upon interaction of Ch - SPIONs with S. aureus and P. aeruginosa at 0.01 g/L concentration, nearly a 2-fold reduction in the number of colonies was observed for both bacteria strains at 48 h of culture. Results cumulatively showed that Ch - SPIONs were potential candidates as a cytocompatible and antibacterial agent that can be targeted to biofilm and imaged using an MRI.

Alternating Droplet Formation by using Tapered Channel Geometry.

The ability to produce a controlled sequence of alternating droplets from two separate sources inside a microfluidic system brings several advantages in microfluidic analysis. The effectiveness of this technique for use in an application depends on the ability of the device to replicate the pattern continuously and accurately. In this work we studied the effect of the dispersed phase channel geometry on generating a repeating pattern of alternating droplets in a cross junction microfluidic device. By measuring the radius of curvature of a droplet at the time of break up, and calculating the Laplace pressure using these values, we analyzed how the angle of taper of the dispersed phase inlet channel has an influence on the pattern repetition and uniformity of formed droplet size and spacing in between. The performance of devices with different angle of taper values were studied experimentally. This comparative study indicated that the ability of a cross junction device to generate alternating droplets with uniform size and spacing is highly dependent on the angle of taper of the inlet channels; and it improves with larger taper angles.