profoundly improved epidemiological control, food safety, and general biodefense. The potential socio-economic impact of getting this right is profound.

Ultrasensitive mediator-free electrochemical detection for biomarker proteins was achieved at low cost using a novel composite of Fe3O4 nanoparticles loaded onto graphene oxide (GO) nanosheets (Fe3O4@GO). This paramagnetic Fe3O4@GO composite (1 μm size range) was decorated with antibodies against prostate specific antigen (PSA) and prostate specific membrane antigen (PSMA), and then used to first capture these biomarkers and then deliver them to an 8-sensor detection chamber of a microfluidic immunoarray. Screen-printed carbon sensors coated with electrochemically reduced graphene oxide (ERGO) and a second set of antibodies selectively capture the biomarker-laden Fe3O4@GO particles, which subsequently catalyze hydrogen peroxide reduction to detect PSA and PSMA. Accuracy was confirmed by good correlation between patient serum assays and enzyme-linked immunosorbent assays (ELISA). Excellent detection limits (LOD) of 15 fg/mL for PSA and 4.8 fg/mL for PSMA were achieved in serum. The LOD for PSA was 1000-fold better than the only previous report of PSA detection using Fe3O4. Dynamic ranges were easily tunable for concentration ranges encountered in serum samples by adjusting the Fe3O4@GO Concentration. Reagent cost was only $0.85 for a single 2-protein assay.

Electrocatalysis of water is a scalable and easily available source of the production of hydrogen (H2), the future energy carrier. This drive for clean energy inspired us to develop an inexpensive, readily producible, highly active, and stable catalyst to replace current state of the art platinum catalysts. Building on the promising hydrogen evolution reaction (HER) activity of many pyrites, their structural tuning by different metals and nonmetals has been found to be effective in several instances. We present here one such effort by partial surface selenization of mesoporous cobalt sulfide material, which displayed long-term operational stability (for at least 25 h) besides attaining a current density of 100 mA cm–2 at an overpotential of 160 mV versus the reversible hydrogen electrode (RHE) (in acidic media). A low Tafel slope (of 52 mV dec–1) and high exchange current density (j 0) (of 70 μA cm–2) make our catalyst better to most existing systems. More importantly, using a variety of analytical techniques, electrochemical measurements, and theoretical calculations, we have analyzed the morphology of the material and rationalized the key to the enhanced intrinsic activity (as compared to the meso-CoS2) per active site. This study is expected to explain similar systems and modify approaches to enhancing the electrochemical activity of metal chalcogenides.

The inability to distinguish aggressive from indolent prostate cancer is a longstanding clinical problem. Prostate specific antigen (PSA) tests and digital rectal exams cannot differentiate these forms. Because only ∼10% of diagnosed prostate cancer cases are aggressive, existing practice often results in overtreatment including unnecessary surgeries that degrade patients' quality of life. Here, we describe a fast microfluidic immunoarray optimized to determine 8-proteins simultaneously in 5 μL of blood serum for prostate cancer diagnostics. Using polymeric horseradish peroxidase (poly-HRP, 400 HRPs) labels to provide large signal amplification and limits of detection in the sub-fg mL −1 range, a protocol was devised for the optimization of the fast, accurate assays of 100-fold diluted serum samples. Analysis of 130 prostate cancer patient serum samples revealed that some members of the protein panel can distinguish aggressive from indolent cancers. Logistic regression was used to identify a subset of the panel, combining biomarker proteins ETS-related gene protein (ERG), insulin-like growth factor-1 (IGF-1), pigment epithelial-derived factor (PEDF), and serum monocyte differentiation antigen (CD-14) to predict whether a given patient should be referred for biopsy, which gave a much better predictive accuracy than PSA alone. This represents the first prostate cancer blood test that can predict which patients will have a high biopsy Gleason score, a standard pathology score used to grade tumors.