Reusable acoustic tweezers for disposable devices.

We demonstrate acoustic tweezers used for disposable devices. Rather than forming an acoustic resonance, we locally transmitted standing surface acoustic waves into a removable, independent polydimethylsiloxane (PDMS)-glass hybridized microfluidic superstrate device for micromanipulation. By configuring and regulating the displacement nodes on a piezoelectric substrate, cells and particles were effectively patterned and transported into said superstrate, accordingly. With the label-free and contactless nature of acoustic waves, the presented technology could offer a simple, accurate, low-cost, biocompatible, and disposable method for applications in the fields of point-of-care diagnostics and fundamental biomedical studies.

A portable low-cost long-term live-cell imaging platform for biomedical research and education.

Time-resolved visualization and analysis of slow dynamic processes in living cells has revolutionized many aspects of in vitro cellular studies. However, existing technology applied to time-resolved live-cell microscopy is often immobile, costly and requires a high level of skill to use and maintain. These factors limit its utility to field research and educational purposes. The recent availability of rapid prototyping technology makes it possible to quickly and easily engineer purpose-built alternatives to conventional research infrastructure which are low-cost and user-friendly. In this paper we describe the prototype of a fully automated low-cost, portable live-cell imaging system for time-resolved label-free visualization of dynamic processes in living cells. The device is light-weight (3.6 kg), small (22 × 22 × 22 cm) and extremely low-cost (<€1250). We demonstrate its potential for biomedical use by long-term imaging of recombinant HEK293 cells at varying culture conditions and validate its ability to generate time-resolved data of high quality allowing for analysis of time-dependent processes in living cells. While this work focuses on long-term imaging of mammalian cells, the presented technology could also be adapted for use with other biological specimen and provides a general example of rapidly prototyped low-cost biosensor technology for application in life sciences and education.

Colorimetric micromethod for protein determination with erythrosin B.

Reaction of erythrosin B with proteins results in a stable, highly colored chromophore with an absorbance maximum at 545 nm. This is the basis for a new quantitative determination method of proteins in solution. The assay can be performed at room temperature, but is faster and more sensitive at 90-95 degrees C. The erythrosin assay is characterized by (i) stable dye-protein color, (ii) high sensitivity (2-14 micrograms/ml protein), (iii) short reaction time (1.5-2 min at 90-95 degrees C), (iv) good reproducibility, (v) limited interference by common reagents, and (vi) low protein-to-protein variability. Thus, the erythrosin assay can be useful for routine analytical purposes and may overcome some of the limitations of other currently employed assays.