Diagnosis and Management of Patients with Suspected Acute Myocardial Infarction

Organic Semiconductor Laser Platform for the Detection of DNA by AgNP Plasmonic Enhancement

Organic semiconductor lasers are a sensitive biosensing platform that respond to specific biomolecule binding events. So far, such biosensors have utilized protein-based interactions for surface functionalization but a nucleic acid-based strategy would considerably widen their utility as a general biodiagnostic platform. This manuscript reports two important advances for DNA-based sensing using an organic semiconductor (OS) distributed feedback (DFB) laser. First, the immobilization of alkyne-tagged 12/18-mer oligodeoxyribonucleotide (ODN) probes by Cu-catalyzed azide alkyne cycloaddition (CuAAC) or "click-chemistry" onto an 80 nm thick OS laser film modified with an azide-presenting polyelectrolyte monolayer is presented. Second, sequence-selective binding to these immobilized probes with complementary ODN-functionalized silver nanoparticles, is detected. As binding occurs, the nanoparticles increase the optical losses of the laser mode through plasmonic scattering and absorption, and this causes a rise in the threshold pump energy required for laser action that is proportional to the analyte concentration. By monitoring this threshold, detection of the complementary ODN target down to 11.5 pM is achieved. This complementary binding on the laser surface is independently confirmed through surface-enhanced Raman spectroscopy (SERS).

Method and apparatus using selected superparamagnetic labels for rapid quantification of immunochromatographic tests

A rapid method and instrumentation for quantification of immunochromatographic tests (ICT) are described. The principle and performance of the method was demonstrated by measuring the levels of human chorionic gonadotropin (hCG) present in urine. The test format was a sandwich assay using two distinct monoclonal antibodies directed against hCG. The first anti-hCG antibody was labeled with superparamagnetic particles whereas the second was immobilized as a narrow detection zone on a porous membrane. The human urine sample was mixed with superparamagnetic particles coated with the first anti-hCG antibody, and the mixture was allowed to migrate past the detection zone containing the second anti-hCG antibody. Capillary forces facilitated migration of the immune complexes along the porous membrane. The amount of superparamagnetic particle-labelled monoclonal anti-hCG bound to the detection zone was directly proportional to the amount of hCG present in the sample as detected by measuring magnetization in the detector coil. The method had a practical detection limit of 20 U/l (54 nM) of hCG per 5 μl of human urine and a linear range of three decades from 20 U/l to 10 000 U/l. In addition, the analysis was completed within less than 10 minutes. Thus, the test format should be suitable for fast detection and monitoring of a large variety of clinically important parameters and analytes.