Bacterial DNA Recognition by SERS Active Plasma-Coupled Nanogold.

It is shown that surface-enhanced Raman spectroscopy (SERS) can identify bacteria based on their genomic DNA composition, acting as a "sample-distinguishing marker". Successful spectral differentiation of bacterial species was accomplished with nanogold aggregates synthesized through single-step plasma reduction of the ionic gold-containing vapored precursor. A high enhancement factor (EF = 107) in truncated coupled plasmonic particulates allowed SERS-probing at nanogram sample quantities. Simulations confirmed the occurrence of the strongest electric field confinement within nanometric gaps between gold dimers/chains from where the molecular fingerprints of bacterial DNA fragments gained photon scattering enhancement. The most prominent Raman modes linked to fundamental base-pair molecular vibrations were deconvoluted and used to proceed with nitrogenous base content estimation. The genomic composition (percentage of guanine-cytosine and adenine-thymine) was successfully validated by third-generation sequencing using nanopore technology, further proving that the SERS technique can be employed to swiftly specify bioentities by the discriminative principal-component statistical approach.

Oriented Carbon Nanostructures from Plasma Reformed Resorcinol-Formaldehyde Polymer Gels for Gas Sensor Applications.

Oriented carbon nanostructures (OCNs) with dominant graphitic characteristics have attracted research interest for various applications due to the excellent electrical and optical properties owing to their vertical orientation, interconnected structures, electronic properties, and large surface area. Plasma enhanced chemical vapor deposition (PECVD) is considered as a promising method for the large-scale synthesis of OCNs. Alternatively, structural reformation of natural carbon precursor or phenol-based polymers using plasma-assisted surface treatment is also considered for the fabrication of OCNs. In this work, we have demonstrated a fast technique for the synthesis of OCNs by plasma-assisted structure reformation of resorcinol-formaldehyde (RF) polymer gels using radio-frequency inductively coupled plasma (rf-ICP). A thin layer of RF polymer gel cast on a glass substrate was used as the carbon source and treated with rf plasma under different plasma discharge conditions. Argon and hydrogen gases were used in surface treatment, and the growth of carbon nanostructures at different discharge parameters was systematically examined. This study explored the influence of the gas flow rate, the plasma power, and the treatment time on the structural reformation of polymer gel to produce OCNs. Moreover, the gas-sensing properties of as-prepared OCNs towards ethanol at atmospheric conditions were also investigated.