Emerging molecular diagnosis requires ultrafast polymerase chain reaction (PCR) on chip for rapid precise detection of infectious diseases in the point-of-care test. Here, we report nanoplasmonic on-chip PCR for rapid precision molecular diagnostics. The nanoplasmonic pillar arrays (NPA) comprise gold nanoislands on the top and sidewall of large-scale glass nanopillar arrays. The nanoplasmonic pillars enhance light absorption of a white light-emitting diode (LED) over the whole visible range due to strong electromagnetic hotspots between the nanoislands. As a result, they effectively induce photothermal heating for ultrafast PCR thermal cycling. The temperature profile of NPA exhibits 30 cycles between 98 and 60 °C for a total of 3 min and 30 s during the cyclic excitation of white LED light. The experimental results also demonstrate the rapid DNA amplification of both 0.1 ng μL −1 of λ-DNA in 20 thermal cycles and 0.1 ng μL −1 of complementary DNA of Middle East respiratory syndrome coronavirus in 30 thermal cycles using a conventional PCR volume of 15 μL. This nanoplasmonic PCR technique provides a new opportunity for rapid precision molecular diagnostics.
The quantitative label-free detection of neurotransmitters provides critical clues in understanding neurological functions or disorders. However, the identification of neurotransmitters remains challenging for surface-enhanced Raman spectroscopy (SERS) due to the presence of noise. Here, we report spread spectrum SERS (ss-SERS) detection for the rapid quantification of neurotransmitters at the attomolar level by encoding excited light and decoding SERS signals with peak autocorrelation and near-zero cross-correlation. Compared to conventional SERS measurements, the experimental result of ss-SERS shows an exceptional improvement in the signal-to-noise ratio of more than three orders of magnitude, thus achieving a high temporal resolution of over one hundred times. The ss-SERS measurement further allows the attomolar SERS detection of dopamine, serotonin, acetylcholine, γ-aminobutyric acid, and glutamate without Raman reporters. This approach opens up opportunities not only for investigating the early diagnostics of neurological disorders or highly sensitive biomedical SERS applications but also for developing low-cost spectroscopic biosensing applications.
Biological wonders, found in insects such as antireflecting moth eyes, compound eyes in a honey bee, firefly lanterns, and iridescent butterfly wings, inspire human beings for advanced light imaging and illumination technologies. Dazzling advances of micro-and nanofabrication technologies allow insect-inspired structures, for example, artificial compound eyes with a wide field of view and low aberration, bioinspired light-emitting diode lenses, and structural coloration templates, featuring miniaturization. Besides, plasmonics and metamaterials offer an unprecedented approach that overcomes the diffraction limit and unveils unknown optical phenomena in ultrastructures inspired by insects. Here, insect-inspired photonic structures for light imaging, light extraction, and structural coloration are reviewed, and photonic functions and structure fabrications inspired by insects that can be applied in advanced imaging and illumination applications are discussed.
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