Using trimesic acid (TMA) as a model system by means of scanning tunneling microscope (STM) equipped with a temperature controller, here, we report a temperature-assisted method to cooperatively control electric-field-induced supramolecular phase transitions at the liquid/solid interface. Octanoic acid is used as a solvent due to its good solubility for TMA and its less complicated pattern formed under negative STM bias (e.g., only chicken-wire polymorphs existing). At positive substrate bias, STM revealed that TMA assembly based on temperature modulations underwent phase transitions from a porous (22 °C) to a flower (45 °C) and further to a zigzag (68 °C) structure. The transitions are ascribed to the partial deprotonation of the carboxyl groups of TMA. Both the temperature and electrical polarity of the substrate are crucial, i.e., the transitions only take place at positive substrate bias and elevated temperatures. Molecular mechanics simulations were carried out to calculate the temperature and electric field dependence of the adsorption enthalpy and free energy of the chicken-wire assembly of TMA on the two layers of graphene surface. The calculated decrease in adsorption enthalpy with the increase of temperature and electric field values that causes the TMA chicken-wire assembly to be less stable is proposed to promote the occurrence of the phase transition observed by STM. This study paves the way toward program-controlled supramolecular phase switching via the synergic effect of electrical and thermal stimuli.
The current study emphasizes the synthesis of iron oxide nanoparticles (IONPs) and impact of hydrophilic polymer polyvinyl alcohol (PVA) coating concentration as well as anticancer drug doxorubicin (DOX) loading on saturation magnetization for target drug delivery applications. Iron oxide nanoparticles particles were synthesized by a reformed version of the co-precipitation method. The coating of polyvinyl alcohol along with doxorubicin loading was carried out by the physical immobilization method. X-ray diffraction confirmed the magnetite (Fe3O4) structure of particles that remained unchanged before and after polyvinyl alcohol coating and drug loading. Microstructure and morphological analysis was carried out by transmission electron microscopy revealing the formation of nanoparticles with an average size of 10 nm with slight variation after coating and drug loading. Transmission electron microscopy, energy dispersive, and Fourier transform infrared spectra further confirmed the conjugation of polymer and doxorubicin with iron oxide nanoparticles. The room temperature superparamagnetic behavior of polymer-coated and drug-loaded magnetite nanoparticles were studied by vibrating sample magnetometer. The variation in saturation magnetization after coating evaluated that a sufficient amount of polyvinyl alcohol would be 3 wt. % regarding the externally controlled movement of IONPs in blood under the influence of applied magnetic field for in-vivo target drug delivery.
The extraordinary optoelectronic properties of platinum diselenide (PtSe2), whose structure is similar to graphene and phosphorene, has attracted great attention in new rapidly developed two-dimensional (2D) materials beyond the other 2D material family members. We have investigated the surface plasmon resonance (SPR) sensors through PtSe2 with the transfer matrix method. The simulation results show that the anticipated PtSe2 biochemical sensors have the ability to detect analytic. It is evident that only the sensitivities of Ag or Au film biochemical sensors were observed at 118°/RIU (refractive index unit) and 130°/RIU, whereas the sensitivities of the PtSe2-based biochemical sensors reached as high as 162°/RIU (Ag film) and 165°/RIU (Au film). The diverse biosensor sensitivities with PtSe2 suggest that this kind of 2D material can adapt SPR sensor properties.
Novel approaches to synthesize efficient inorganic electride [Ca24Al28O64]4+(e−)4 (thereafter, C12A7:e−) at ambient pressure under nitrogen atmosphere, are actively sought out to reduce the cost of massive formation of nanosized powder as well as compact large size target production. It led to a new era in low cost industrial applications of this abundant material as Transparent Conducting Oxides (TCOs) and as a catalyst. Therefore, the present study about C12A7:e− electride is directed towards challenges of cation doping in C12A7:e− to enhance the conductivity and form target to deposit thin film. Our investigation for cation doping on structural and electrical properties of Sn- and Si-doped C12A7:e− (Si-C12A7:e, and Sn-C12A7:e−) reduced graphene oxide (rGO) composite shows the maximum achieved conductivities of 5.79 S·cm−1 and 1.75 S·cm−1 respectively. On the other hand when both samples melted, then rGO free Sn-C12A7:e− and Si-C12A7:e− were obtained, with conductivities ~280 S.cm−1 and 300 S·cm−1, respectively. Iodometry based measured electron concentration of rGO free Sn-C12A7:e− and Si-C12A7:e−, 3 inch electride targets were ~2.22 × 1021 cm−3, with relative 97 ± 0.5% density, and ~2.23 × 1021 cm−3 with relative 99 ± 0.5% density, respectively. Theoretical conductivity was already reported excluding any associated experimental support. Hence the above results manifested feasibility of this sol-gel method for different elements doping to further boost up the electrical properties.
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