Researchers developed a diagnostic platform dubbed Nanoplasmonic Electrical-field Enhanced Resonating Device (NE2RD), which consists of a gold nanoparticle-coated polystyrene surface onto which reagents such as antibodies are immobilized.
Under varying conditions of temperature, pH, and ionic strength, the device detected a range of biological targets, including proteins, viruses, bacteria, and drugs, often without the need for labels or tags and in droplets of clinical samples such as blood, serum, and saliva.
By tracking nanoparticle oscillations, NE2RD, which has a linear dynamic range of around eight orders of magnitude, reliably the immune molecule IFN-γ at 400 fg/mL concentration; the detection limit for the enzyme-linked immunosorbent assay, a standard diagnostic method, was around 250 pg/mL.
Measurements of levels of HIV-1 and Kaposi’s sarcoma-associated herpes simplex virus, which are common coinfections, in patients’ serum and saliva not only mirrored those obtained through established PCR-based techniques but also indicated patients’ response to treatment, suggesting the clinical validity of the device.
Further, the authors integrated NE2RD into a disposable, portable chip without significant loss of detection sensitivity. According to the authors, NE2RD may represent a prototype for a portable, point-of-care diagnostic device.