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Abstract:
Conducting polymers enable the simultaneous transport of electrons and ions within soft, biocompatible matrices. Yet their synthesis typically relies on soluble oxidants that generate stoichiometric waste and inhibit high-resolution patterning. Nanometer-thick gold films deposited by direct-current magnetron sputtering in dilute air function concurrently as a template and intrinsic oxidant—though, owing to their discontinuous structure, not as current collectors—for the reagent-free growth of emeraldine-salt polyaniline (PANI-ES). X-ray photoelectron spectroscopy reveals that freshly sputtered films contain approximately 60% Au2O3, which is quantitatively reduced by aniline within 60 s. In situ UV–vis spectroscopy records an increase in the 750 nm polaron band that scales linearly with oxide thickness. Polymerization self-terminates once the local Au(III) reservoir is exhausted, yielding patterns precisely registered to the underlying metal mask. The resulting PANI-ES retains the optical, Raman, and electrochemical signatures of the highly conductive emeraldine salt. By replacing soluble oxidants with a solid Au2O3 underlayer, the process avoids sulfate-containing solution-phase by-products and enables aniline-to-PANI conversion at room temperature under ambient air, providing a straightforward route to patterned PANI films without post-growth wet lithography for hole-transport layers, neural microelectrodes, and chemiresistors.

Keywords:
bioelectronics, gold oxide nanofilms, polyaniline, reagent-free oxidant polymerization, site-confined growth

Abstract:
While a significant progress has recently been made in therapy of many cancers, the cure for some high grade cancers, such as the astrocytic cancers, remains elusive. In the latter case, specificity and functionality of the brain tissue limit the options available to surgical and chemotherapeutic treatments. In view of the prospects of reversible blood-brain barrier opening, we have investigated the possibility of a transfection of malignant astrocyte cells with novel graphene oxide nanosheet (GONS) nanocarrier-supported molecular beacons (MB) encoded for the detection of a biomarker survivin (Sur). The behavior of GONS-supported SurMBs (GONS@SurMB) has been characterized using fluorescence spectroscopy, SEM, TEM, Raman spectroscopy, melting transients, resonance elastic light scattering, and cell viability testing. With the GONS@SurMB, we have achieved the limit of detection for tDNA at 37°C: LOD = 24 nM (S/N = 3). In tests with complementary targets and mismatched strands, the proposed fluorescent turn-on GONS@SurMB probes have shown a single-nucleotide polymorphism sensitivity. We have demonstrated the transfection of U-87 MG astrocyte cells with GONS@SurMB nanocarriers which release SurMB upon mRNA detection. The MTT tests indicate that the GONS carrier concentrations up to 133 μg/mL are not cytotoxic to astrocyte cells, although a cell assembly has been encountered at higher carrier concentrations. The GONS alone does not assemble appreciably up to 80 μg/mL. The proposed method can be used for the detection of Sur mRNA in malignant cells and the GONS@SurMB nanocarriers can also be considered as viable candidates for future gene therapy of brain cancers.

Keywords:
Survivin detection, Molecular beacon, Graphene oxide nanocarrier, Survivin mRNA, U-87 malignant glioma cells