Literature Review on Point-of-Care Testing (August 2009-December 2010)

In-situ preparation of lactate-sensing membrane for the noninvasive and wearable analysis of sweat

In the wearable electrochemical biosensors, sensing signal duration is significantly dependent on the long-term stability of functional materials modified on the flexible substrate, the effect of pH changes of sweat on the sensing device and signal fluctuation caused by the bending of sensor. Here, we proposed a wearable biosensor based on the lactate-sensing membrane mainly constituted by Prussian blue (PB), reduced graphene oxide (rGO), Au nanoparticles and lactate oxidase (LOx). Based on the in-situ layer-by-layer spin-coating preparation method, the electrode surface was covered with an extensive and uniform PB/GO membrane with a high stability. After the electro-reduction of GO to rGO and the combination of urchin-like Au particles with sufficient tentacles to LOx, the sensing membrane showed the improved electron transport from the enzyme active center to the electrode. Therefore, the wearable biosensor achieved a high sensitivity of 40.6 μA mM^-1 cm^-2 in a range of 1-222 μM and a low sensitivity of 1.9 μA mM^-1 cm^-2 in a wide range of 0.222-25 mM, satisfying the requirement of the typical test. In addition, with the excellent running and mechanical stability, the lactate biosensor was successfully applied on volunteers' skin for real-time monitoring of perspiration in vivo. The results were comparable with ex vivo measurements achieved by a commercial lactate sensor. The wearable electrochemical biosensor provides a good candidate in the future for the evaluation of human sweat in sports and biomedical fields.

Porous bead-based diagnostic platforms: bridging the gaps in healthcare

Advances in lab-on-a-chip systems have strong potential for multiplexed detection of a wide range of analytes with reduced sample and reagent volume; lower costs and shorter analysis times. The completion of high-fidelity multiplexed and multiclass assays remains a challenge for the medical microdevice field; as it struggles to achieve and expand upon at the point-of-care the quality of results that are achieved now routinely in remote laboratory settings. This review article serves to explore for the first time the key intersection of multiplexed bead-based detection systems with integrated microfluidic structures alongside porous capture elements together with biomarker validation studies. These strategically important elements are evaluated here in the context of platform generation as suitable for near-patient testing. Essential issues related to the scalability of these modular sensor ensembles are explored as are attempts to move such multiplexed and multiclass platforms into large-scale clinical trials. Recent efforts in these bead sensors have shown advantages over planar microarrays in terms of their capacity to generate multiplexed test results with shorter analysis times. Through high surface-to-volume ratios and encoding capabilities; porous bead-based ensembles; when combined with microfluidic elements; allow for high-throughput testing for enzymatic assays; general chemistries; protein; antibody and oligonucleotide applications.

Microfluidics and the life sciences

The field of microfluidics, often also referred to as "Lab-on-a-Chip" has made significant progress in the last 15 years and is an essential tool in the development of new products and protocols in the life sciences. This article provides a broad overview on the developments on the academic as well as the commercial side. Fabrication technologies for polymer-based devices are presented and a strategy for the development of complex integrated devices is discussed, together with an example on the use of these devices in pathogen detection.