Hydrogen peroxide (H2O2) is known as a key molecule in a variety of biological processes, as well as a crucial byproduct in many enzymatic reactions. Therefore, being able to selectively and sensitively detect H2O2 is not only important in monitoring, estimating and decoding H2O2 relevant physiological pathways, but also very helpful in developing enzymatic-based biosensors towards other analytes of interest. Herein, we report a plasmonic probe for H2O2 based on 3-mercaptophenylboronic acid (3-MPBA) modified gold nanoparticles (AuNPs) which is coupled with surface-enhanced Raman scattering (SERS) to yield a limit of detection (LOD) of 70 nM. Our probe quantifies both exogenous and endogenous H2O2 levels in living cells and can further be coupled with glucose oxidase (GOx) to achieve quantitative and selective detection of glucose in artificial urine and human serum.

A probe mediated SERS-based strategy is developed to selectively detect hydrazine with superb sensitivity. Ortho-phthaldialdehyde, a simple probe, reacts specifically with hydrazine to form phthalazine, a molecule that possesses a larger Raman cross section and better affinity toward the SERS substrate. We observed a limit of detection of 8.5 × 10(-11) M. Our method shows both qualitative and quantitative measurement of hydrazine with high sensitivity, low cost, and fast analysis time.

Owing to its extreme sensitivity and easy execution, surface-enhanced Raman spectroscopy (SERS) now finds application for a wide variety of problems requiring sensitive and targeted analyte detection. This widespread application has prompted a proliferation of different SERS-based sensors, suggesting the need for a framework to classify existing methods and guide the development of new techniques. After a brief discussion of the general SERS modalities, we classify SERS-based sensors according the origin of the signal. Three major categories emerge from this analysis: surface-affinity strategy, SERS-tag strategy, and probe-mediated strategy. For each case, we describe the mechanism of action, give selected examples, and point out general misconceptions to aid the construction of new devices. We hope this review serves as a useful tutorial guide and helps readers to better classify and design practical and effective SERS-based sensors.

A series of oxamyl dipeptides were optimized for pan caspase inhibition, anti-apoptotic cellular activity and in vivo efficacy. This structure-activity relationship study focused on the P4 oxamides and warhead moieties. Primarily on the basis of in vitro data, inhibitors were selected for study in a murine model of alpha-Fas-induced liver injury. IDN-6556 (1) was further profiled in additional in vivo models and pharmacokinetic studies. This first-in-class caspase inhibitor is now the subject of two Phase II clinical trials, evaluating its safety and efficacy for use in liver disease.

A unified strategy enables multi-component radical addition cascades to couple alkenes, heteroarenes, and various radicals, including N3, P(O)R2, and CF3.

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A polarity-reversing radical cascade strategy for alkene di-functionalization by vicinal C-C and C-P bond-formation has been developed. This approach to concurrently adding phosphorous and a heteroarene across an olefin is enabled by photocatalytic generation of electrophilic P-centered radicals. Upon chemoselective addition to an olefin, the resulting nucleophilic C-centered radical selectively combines with electrophilic heteroarenes, such as pyridines. This multi-component coupling scheme for phosphinylalkylation complements classic two-component methods for hydrophosphinylation of alkenes and C-H phosphinylation of arenes. Included competition and photo-quenching experiments provide insight into the selectivity and mechanism of this polarityreversal pathway.

Surface-enhanced Raman scattering (SERS) spectra have been successfully recorded from individual, selected clusters of colloidal silver particles on which phthalazine, dopamine, or 2,2‘-bipyridine was adsorbed. The method involved the controlled deposition of silver colloid aggregates onto a Pyrex microscope cover slide and the selection of an individual cluster by the optical microscope of a micro-Raman spectrometer followed by Raman measurement. SERS spectra of clusters of various size were recorded. With phthalazine, good quality SERS spectra were obtained with 476.2- and 530.9-nm laser excitation. Poor spectra were obtained with 568.2- and 590-nm excitation, probably due to the photofragmentation of the cluster. The wavelength at which photofragmentation occurred was cluster size and structure dependent. Smaller clusters tended to fragment at shorter wavelengths. A micropreparative technique was developed for preparing single adsorbate-covered silver colloid aggregates. Using this technique in conjunction with Raman microscopy, good quality SERS spectra were obtained from 5 pmol of phthalazine and dopamine. SERS spectra of 2,2‘-bipyridine deposited out of a dichloromethane solution also were obtained, illustrating the possibility of using this single-cluster technique for recording SERS spectra of water-insoluble adsorbates or of adsorbates dissolved in nonaqueous solvents.