Microscale and Nanoscale Electrophotonic Diagnostic Devices.

Detecting and identifying infectious agents and potential pathogens in complex environments and characterizing their mode of action is a critical need. Traditional diagnostics have targeted a single characteristic (e.g., spectral response, surface receptor, mass, intrinsic conductivity, etc.). However, advances in detection technologies have identified emerging approaches in which multiple modes of action are combined to obtain enhanced performance characteristics. Particularly appealing in this regard, electrophotonic devices capable of coupling light to electron translocation have experienced rapid recent growth and offer significant advantages for diagnostics. In this review, we explore three specific promising approaches that combine electronics and photonics: (1) assays based on closed bipolar electrochemistry coupling electron transfer to color or fluorescence, (2) sensors based on localized surface plasmon resonances, and (3) emerging nanophotonics approaches, such as those based on zero-mode waveguides and metamaterials.

SERS immunoassay based on the capture and concentration of antigen-assembled gold nanoparticles.

A simple, rapid, and sensitive immunoassay has been developed based on antigen-mediated aggregation of gold nanoparticles (AuNP) and surface-enhanced Raman spectroscopy (SERS). Central to this platform is the extrinsic Raman label (ERL), which consists of a gold nanoparticle modified with a mixed monolayer of a Raman active molecule and an antibody. ERLs are mixed with sample, and antigen induces the aggregation of the ERLs. A membrane filter is then used to isolate and concentrate the ERL aggregates for SERS analysis. Preliminary work to establish proof-of-principle of the platform technology utilized mouse IgG as a model antigen. The effects of membrane pore diameter and AuNP size on the analytical performance of the assay were systematically investigated, and it was determined that a pore diameter of 200 nm and AuNP diameter of 80 nm provide maximum sensitivity while minimizing signal from blank samples. Optimization of the assay provided a detection limit of 1.9 ng/mL, 20-fold better than the detection limit achieved by an ELISA employing the same antibody-antigen system. Furthermore, this assay required only 60 min compared to 24h for the ELISA. To validate this assay, mouse serum was directly analyzed to accurately quantify IgG. Collectively, these results demonstrate the potential advantages of this technology over current diagnostic tests for protein biomarkers with respect to time, simplicity, and detection limits. Thus, this approach provides a framework for prospective development of new and more powerful tools that can be designed for point-of-care diagnostic or point-of-need detection.

The predictive value of the first postnatal ultrasound in children with antenatal hydronephrosis.

OBJECTIVE: To evaluate the effectiveness of the first postnatal ultrasound (US) in predicting the final postnatal diagnosis using a database of children followed prospectively for antenatal hydronephrosis, and to compare these findings with a systematic review of the literature. METHODS: The study involved 1441 children who had their radiological evaluation between 3 and 60 days of life, including an US, performed at our institution in 1998-2006. Univariate and multivariate analyses were performed. A systematic review of articles on prenatal hydronephrosis resulted in 31 studies with 2202 patients who met the inclusion criteria for analysis. RESULTS: 62.0% of renal units (RUs) had transient or non-obstructive hydronephrosis. Increasing degree of hydronephrosis correlated with increased risk of urological pathologies (from 29.6% RUs in the mild group to 96.3% RUs in the severe group). A systematic review of the literature indicated very poor quality data, but the findings appeared to be concordant with those from our patient population. CONCLUSION: The findings from this study will help to quantify the incidence of postnatal pathology based upon the first postnatal US parameters. This information is useful for counseling and for determining which postnatal radiological tests will be necessary.