Morphological Growth and Theoretical Understanding of Gold and Other Noble Metal Nanoplates

Temperature Sensitive PNIPAm-g-PEI/Gold Nanotriangle for Gene Delivery Promotion

As a two-dimensional material, gold nanotriangles (GNTs) are rarely studied in the field of gene delivery. In this study, a temperature-responsive GNTs was developed as a novel carrier for gene delivery. The temperature-sensitive copolymer PNIPAm-g-PEI was grafted onto the surface of GNTs to construct a PNIPAm-g-PEI/GNTs composite controllable release platform. The lower critical solution temperature (LCST) of PNIPAm-g-PEI/GNTs was found to be 42 °C, and the particle size of PNIPAm-g-PEI/GNTs was 150 nm at this temperature. Gel electrophoresis experiments showed that PNIPAm-g-PEI/GNTs completely condensed DNA at 20 μg/mL, and PNIPAm-g-PEI/GNTs promoted the release of DNA under laser irradiation. Luciferase and green fluorescent protein reporter gene assays demonstrated that the transfection efficiency of PNIPAm-g-PEI/GNTs was 1.5 and 7.2 times that of PEI, respectively. These results demonstrated the promising potential of temperature-responsive GNTs as effective and safe gene delivery vectors.

In Situ Nucleic Acid Amplification and Ultrasensitive Colorimetric Readout in a Paper-Based Analytical Device Using Silver Nanoplates

A rapid, highly sensitive, and quantitative colorimetric paper-based analytical device (PAD) based on silver nanoplates (AgNPls) and loop-mediated isothermal amplification (LAMP) is presented. It is shown that cauliflower-like concatemer LAMP products can mediate crystal etching of AgNPls, with a threefold signal enhancement versus linear dsDNA. Methicillin-resistant Staphylococcus aureus (MRSA), an antimicrobial resistant bacterium that poses a formidable risk with persistently high mortality, is used as a model pathogen. Due to the excellent color contrast provided by AgNPls, the PAD allows qualitative analysis by the naked eye and quantitative analysis using a smartphone camera, with detection limits down to a single copy in just 30 min, and a linear response from 1 to 10⁴ copies (R² = 0.994). The entire assay runs in situ on the paper surface, which drastically simplifies operation of the device. This is the first demonstration of single copy detection using a colorimetric readout, and the developed PAD shows great promise for translation into an ultrasensitive gene-based point-of-care test for any infectious disease target, via modification of the LAMP primer set.

Effect of the Air/Water Interfacial Properties of Amine Derivatives on the in Situ Fabrication of Microsized Gold Sheets

Development of new methods for producing large-area nanocrystals with specific shapes is crucial for advancements in various fields. In this study, submillimeter-sized sheet-structured gold crystals with nanoscale thicknesses were fabricated by chemical reduction of HAuCl₄ in the presence of long-chain amidoamine-derived surfactants (C nAOH; n = 12, 14, 16, or 18) in aqueous solutions. Using the C18AOH system at 30 °C, large-area sheet-structured crystals with widths of ∼100 μm and thicknesses of 30 nm were effectively obtained at the air/water interface. The crystal size depended on the temperature and the alkyl-chain length of the surfactant. An investigation of the relationship between the crystal growth and the interfacial properties of C nAOH revealed that large-area crystals were obtained when densely packed molecular layers of long-chain C nAOH were formed at the air/water interface. The interfacial molecular layer of C18AOH showed most effective soft-templating effect and contributed in promoting the growth of sheet-structured gold crystals.