Labs-on-a-Chip: origin, highlights and future perspectives. On the occasion of the 10th microTAS conference

Microanalyser Prototype for On-Line Monitoring of Copper(II) Ion in Mining Industrial Processes

A microanalyzer prototype for copper(II) ion monitoring in mining industrial processes is presented. The microanalyzer is designed as an assembly of different modules, each module being responsible for a unit operation. In order to optimize the industrial processes, the microanalyzer can automate all sample management, signal processing, and mathematical calculations and wirelessly transfer data to a control room. The determination of copper(II) ion is done using a colorimetric reaction and the microanalyser performs autocalibration by in situ dilution of a stock solution, matching the higher analyte concentration of the working range defined for the sample to be determined, using a multicommutation approach. The performance of the microanalyzer for monitoring copper(II) ion in water effluents of mining facilities was optimized in the working range from 1 to 10 mg/L to match Mexican environmental law regulations, which allow a maximum concentration of 4 mg/L of copper(II) ion in these circumstances.

Inducing microscopic thermal lesions for the dissection of functional cell networks on a chip

We present a versatile chip-based method to inflict microscopic lesions on cellular networks or tissue models. Our approach relies on resistive heating of microstructured conductors to impose highly localized thermal stress on specific regions of a cell network. We show that networks can be precisely dissected into individual subnetworks using a microwire crossbar array. To this end, we pattern a network of actively beating cardiomyocyte-like cells into smaller subunits by inflicting thermal damage along selected wires of the array. We then investigate the activity and functional connectivity of the individual subnetworks using a Ca(2+) imaging-based signal propagation analysis. Our results demonstrate the efficient separation of functional activity between individual subnetworks on a microscopic level. We believe that the presented technique may become a powerful tool for investigating lesion and regeneration models in cellular networks.

Core-shell Ag@SiO(2) nanoparticles concentrated on a micro/nanofluidic device for surface plasmon resonance-enhanced fluorescent detection of highly reactive oxygen species

A micro/nanofluidic device integrating a nanochannel in a microfluidic chip was developed for sensitive fluorescent determination of highly reactive oxygen species (hROS) enhanced by surface plasmon resonance-enhanced fluorescence (SPREF). The nanochannel was simply fabricated by polyaniline nanostructures modified on a glass slide. Core-shell Ag@SiO2 nanoparticles were concentrated in front of the nanochannel for fluorescence enhancement based on the SPREF effect. As a demonstration, hROS in the mainstream of cigarette smoke (CS) were detected by the present micro/nanofluidic device. The fluorescent probe for trapping hROS in puffs of CS employed a microcolumn that was loaded with a composite of DNA (conjugated fluorophores, FAM) and Au membrane (coated on cellulose acetate). With a laser-induced fluorescence detection device, hROS was determined on the basis of the amount of FAM groups generated by DNA cleavage. With the optimization of the trapping efficiency, we detected about 4.91 pmol of hROS/puff in the mainstream CS. This micro/nanofluidic-SPREF system promises a simple, rapid, and highly sensitive approach for determination of hROS in CS and other practical systems.

Biological measures of the standard of living

When economists investigate long-term trends and socioeconomic differences in the standard of living or quality of life, they have traditionally focused on monetary measures such as gross domestic product--which has occupied center stage for over 50 years. In recent decades, however, scholars have increasingly recognized the limitations of monetary measures while seeking useful alternatives. This essay examines the unique and valuable contributions of four biological measures--life expectancy, morbidity, stature, and certain features of skeletal remains--to understand levels and changes in human well-being. People desire far more than material goods and in fact they are quite willing to trade or give up material things in return for better physical or psychological health. For most people, health is so important to their quality of life that it is useful to refer to the "biological standard of living." Biological measures may be especially valuable for historical studies and for other research circumstances where monetary measures are thin or lacking. A concluding section ruminates on the future evolution of biological approaches in measuring happiness.

The micro-Petri dish, a million-well growth chip for the culture and high-throughput screening of microorganisms

A miniaturized, disposable microbial culture chip has been fabricated by microengineering a highly porous ceramic sheet with up to one million growth compartments. This versatile culture format, with discrete compartments as small as 7 x 7 mum, allowed the growth of segregated microbial samples at an unprecedented density. The chip has been used for four complementary applications in microbiology. (i) As a fast viable counting system that showed a dynamic range of over 10,000, a low degree of bias, and a high culturing efficiency. (ii) In high-throughput screening, with the recovery of 1 fluorescent microcolony in 10,000. (iii) In screening for an enzyme-based, nondominant phenotype by the targeted recovery of Escherichia coli transformed with the plasmid pUC18, based on expression of the lacZ reporter gene without antibiotic-resistance selection. The ease of rapid, successive changes in the environment of the organisms on the chip, needed for detection of beta-galactosidase activity, highlights an advantageous feature that was also used to screen a metagenomic library for the same activity. (iv) In high-throughput screening of >200,000 isolates from Rhine water based on metabolism of a fluorogenic organophosphate compound, resulting in the recovery of 22 microcolonies with the desired phenotype. These isolates were predicted, on the basis of rRNA sequence, to include six new species. These four applications suggest that the potential for such simple, readily manufactured chips to impact microbial culture is extensive and may facilitate the full automation and multiplexing of microbial culturing, screening, counting, and selection.