Accurate thermometry at micro- and nanoscales is essential in many nanobiotechnological applications. The nanothermometers introduced in this paper are composed of labeled molecular beacons (MBs) comprising gold nanoparticles (AuNPs) on which, depending on application, many MBs of one or more types are immobilized. In this design, three differently labeled MBs with different thermostabilities function as the sensing elements, and AuNPs act as carriers of the MBs and also quenchers of their fluorophores. This flexible design results in a number of nanothermometers with various temperature-sensing ranges. At the lowest temperature, the MBs are in the closed form, where they are quenched. By increasing the temperature, the MBs start to open with respect to their melting points (Tm), and as a result, the fluorescence emission will increase. The temperature resolution of the nanoprobes over a range of 15-60 °C is less than 0.50 °C, which indicates their high sensitivity. Such a good temperature resolution is a result of the specific design of the unusual less stable MBs and also presence of many MBs on AuNPs. The reproducibility and precision of the probes are also satisfactory. The multiplex MB nanoprobe is suitable for thermal imaging by fluorescence microscopy.

The single stranded DNA can be adsorbed on the negatively charged surface of gold nanoparticles (AuNPs), but the rigid structure of double stranded DNA prevents it from adsorption. Signal of a tagged single stranded DNA will be quenched by the plasmon effect of the AuNP surface after its adsorption. This phenomenon has been used to study the DNA hybridization and interactions of two complementary 21mer oligonucleotides each tagged with a different fluorescent dye in the presence of 13 nm gold nanoparticles. The DNA strands used in this study belong to the genome of HIV. The obtained rank deficient three-way fluorescence data sets were resolved by both PARAFAC and restricted Tucker3 models. This is the first successful application of a multiway chemometric technique to analyze multidimensional nanobiological data. The restricted Tucker3 showed a better performance compared to PARAFAC in resolving the data sets. The advantages of restricted Tucker3 analysis over the unrestricted one, i.e., the limited rotational freedom (more unique results) and better interpretability of the obtained results, were experienced in this study. The resolved excitation, emission, and concentration profiles and specially fluorescence resonance energy transfer (FRET) profiles obtained by restricted Tucker3 were chemically more meaningful than those obtained from PARAFAC.

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A series of 1-[2-hydroxyethoxy-methyl]-6-(phenylthio)thymine] (HEPT) derivatives, as nonnucloside reverse transcriptase inhibitors (NNRTIs), was investigated using a nonlinear quantitative structureanti-HIV-1-activity relationship (QSAR) study. Molecular descriptors derived solely from molecular structure were used to represent molecular structure. Utilizing successive projections algorithm (SPA) and a stepwise backward elimination, a subset of 11 descriptors were selected. Application of SPA minimizes the collinearity between the selected descriptors, which are known to be responsible for the anti-HIV-1 activity. Three layer radial basis function networks (RBFNs) were used to construct the nonlinear QSAR models in all stages of study. The relative standard error percent in anti-HIV activity predictions for the training set by the application of cross-validation (RSECV%) was 9.94%, and for prediction set (RSEP%) was 9.99%. The obtained model outperforms those given in the literature in both the fitting and predicting stages. RBFN analysis yielded predicted activities in the excellent agreement with the experimentally obtained values (cross-validation r ¼ 0.927, prediction r ¼ 0.925).

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