Syntheses, structural, and photoluminescence properties of {[4-X-3,5-(CF3)2Pz]M}3 (X = Cl or Br, M = Cu or Ag) containing a heavier halide at the pyrazolyl ring 4-positions are reported. The Cu2O and Ag2O react with [4-Cl-3,5-(CF3)2Pz]H or [4-Br-3,5-(CF3)2Pz]H to form the corresponding metal pyrazolates, which are trinuclear adducts of the type {[4-X-3,5-(CF3)2Pz]M}3 with a nine-membered M3N6 metallacyclic core. They also feature relatively short M···Cl or M···Br intertrimer separations (∼ 3.6 Å) leading to supramolecular aggregates in the solid state. Distinct from the 4-H analogues {[3,5-(CF3)2Pz]M}3, none of the four complexes described herein exhibits short intertrimer metal-metal interactions (as closest such M···M separations are at a distance greater than 5.0 Å). The {[4-X-3,5-(CF3)2Pz]M}3 adducts exhibit bright photoluminescence even at room temperature. The photophysical data suggest that the {[4-X-3,5-(CF3)2Pz]Cu}3 complexes emit from an associative excited state, and the drastic Stokes shift suggests a significant change to the ground state structure of the trinuclear moiety and/or intermolecular interactions upon photoexcitation. The {[4-X-3,5-(CF3)2Pz]Ag}3 complexes emit from a ligand-centered excited state affected by silver and the heavier halogens. Thin films of {[4-X-3,5-(CF3)2Pz]Cu}3 trimers are promising for volatile organic compound (VOC) sensor applications as they exhibit luminescence color change upon exposure to vapors of benzene and its alkylated derivatives.

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A simple photochemical method for making conjoined bi-metallic gold-silver (Au/Ag) nanotwins, a new breed of nanoparticles (NPs), is developed. To the best of our knowledge, the photochemical method resulted in distinct, conjoined, bimetallic nanotwins that are different from any well-established alloyed or core-shell nanostructures in the literature. The conjoined Au-Ag NPs possessed surface plasmon resonance (SPR) properties of both metals. The bimetallic nanostructures possessing distinctive optical properties of both metals were obtained using Au NPs as seeds in the first step, followed by the addition of a silver precursor as feed in the second step during a photochemical irradiation process. In the first step, small, isotropic or large, anisotropic Au NPs are generated by photoinduced reduction within a biocompatible chitosan (CS) polymer. In the second step, a silver precursor (AgNO3) is added as the feed to the AuNPs seed, followed by irradiation of the solution in the ice-bath. The entire photochemical irradiation process resulting in the formation of bimetallic Au-AgNPs did not involve any other reducing agents or stabilizing agents other than the CS polymer stabilizer. The small, conjoined Au-Ag bi-metallic NPs exhibited SPR with peak maxima centering at ~400 nm and ~550 nm, whereas the large conjoined nanoparticles exhibited SPR with peak maxima centering at ~400 nm, 550 nm, and 680 nm, characteristic of both gold and silver surface plasmons in solution. The tunability in the SPR and size of the bimetallic NPs were obtained by varying the reaction time and other reaction parameters, resulting in average sizes between 30 and 100 nm. The SPR, size, distribution, and elemental composition of the bi-metallic NPs were characterized using UV-Vis absorption, electron microscopy, and energy dispersive X-ray spectroscopy (EDS) studies.

In this communication, we present a streamlined, reproducible synthetic method for the production of size-tunable poly(methyl methacrylate) (PMMA) nanoparticles (PMMANPs) and amine-functionalized block-copolymer PMMANPs (H2N-PMMANPs) by varying subcritical concentrations (i.e., below the concentration required to form micelles at 1 atm and 20 °C) of sodium dodecyl sulfate (SDS). We plotted the Z-average size data against SDS concentration, which revealed a second-order exponential decay function, expressed as A 1 e − x t 1 + A 2 e − x t 2 + y 0 . The surfactant concentration (wt./wt.%) has been selected as independent variable x. This function is valid at least for the size range of 20 nm to 97 nm (PMMANPs) and 20 nm to 133 nm (H2N-PMMANPs).

Glioblastomamultiforme (GBM) is a dreadful primary brain tumor characterized with extremely poor prognosis and survival rate, despite available treatments. The failure of current therapies to eliminate specific subpopulations within heterogeneous GBM has been considered a key factor contributing to the inevitable recurrence after treatments. To address this concern, it is necessary to develop novel treatments, which can kill all the GBM cells or at least convert the heterogeneous GBM population to homogeneous populations, which can be easily targeted. In this study, we investigated the effects of Ag-PMMA-PAA nanoparticles (Silver np's) on human malignant glioma(U251) cells and Silver np's role in combinational use with low-level He-Ne laser (632.8nm) against U251 cells.The Silver np's were synthesized using a green chemistry approach and were then characterized using spectroscopic methods. Dose and time dependent studies revealed that the maximum killing (81%) of U251 cells occurred at 225μM Silver np's over 6 hours. Moreover, combined HeNe laser exposure resulted in overall cell death of 92%. Western analysis suggests caspase family members, other than caspase 9, are involved in killing Silver np treated U251 cells or the combination treatment. Thus, our Silver np and low-level laser combination treatment could have a potential application in enhancing chemotherapy for malignant glioma. Citation Format: Rohini Atluri, Daniel Korir, Nishant Tyagi, Eunyoung Kim, Tae-Youl Choi, Denise P. Simmons. A potential treatment for malignant glioblastoma: Silver nanoparticles and low-level laser combination [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6436.