https://www.selleckchem.com/ Gold nanoparticle-core spherical nucleic acids (AuNP core-SNAs), by virtue of the programmable nature of oligonucleotides, have yielded access to the innovative strategies for targeted biodiagnostics. Here, DNA-directed self-assembly of AuNP core-SNAs has been used to design a colorimetric method to sense HIV-1 viral nucleic acid. This strategy utilizes an oligonucleotide with sequence of 5'-untranslated region (5' UTR) of the HIV-1 RNA genome anchored on the surface of AuNPs and a complementary linker strand with a palindromic sequence tail. In the absence of HIV-1 target nucleic acid the complementary linker induces self-assembly of SNAs based on sequence symmetry in the free palindromic tail which can bridge two DNA double helices. While in the presence of the target DNA, due to linker-target duplex formation, the colloidal stability and the red color of the SNAs solution are preserved. Picomole amounts of target DNA can easily be detected with the naked eyes. A 95-mer synthetic DNA strand with the same sequence of HIV-1 viral RNA was utilized for positive control of HIV-1 RNA. The selectivity of the selected linker was satisfactory up to 90% match. Magnetic restricted-access carbon nanotubes (M-RACNTs) were synthesised and used for dispersive solid phase extraction of organophosphates (chlorpyriphos, malathion, disulfoton, pirimiphos) from commercial bovine raw milk samples. Due to their magnetic susceptibility, M-RACNTs were easily separated from the samples/solvents using a neodymium magnet, and the extracted organophosphates were analysed by gas chromatography-mass spectrometry. The protein exclusion capacity was about 100%. Kinetic and isotherm data (for M-RACNTs - malathion interaction) were adequately adjusted to the pseudo-second order and Sips models, respectively, and the maximum adsorption capacity was about 0.55 mg g-1. The method presented linear ranges from 5.0 to 40.0 μg L-1 for all analytes, with determination coeffici