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Transition metal dichalcogenides (TMDCs) and two-dimensional organic and inorganic hybrid lead halide perovskites (2DPVSKs) have emerged as highly promising materials for ultralight and ultrathin optoelectronics application. They both exhibit tunability of electronic properties such as band structure, and they can form heterostructures with various types of two-dimensional materials for novel physical properties not observed in single components. However, TMDCs exhibit poor emission efficiency due to defect states and direct-to-indirect interband transition, and 2DPVSKs suffer from poor stability in ambient atmosphere. Here we report that fabrication of TMDC-on-2DPVSK heterostructures using a solvent-free process leads to novel optical transitions unique to the heterostructure which arise from the hybrid interface and exhibit a strong photoluminescence. Moreover, a two orders of magnitude enhancement of the photoluminescence as compared to WS2 emission is observed. The TMDC on top of 2DPVSK also significantly improves the stability as compared to bare 2DPVSK. Enhanced emission can be explained by electronic structure modification of TMDC by novel interfacial interactions between TMDC and 2DPVSK materials, which shows promise of the heterostructure for high efficiency and stable optoelectronic devices.

Magnetic Block Ionomer Clusters (MBIClusters) with hydrophilic ionic cores and nonionic coronas have been prepared that have ultrahigh transverse NMR relaxivities together with capacities for incorporating high concentrations of polar antibiotic payloads. Magnetite-polymer nanoparticles were assembled by adsorbing the polyacrylate block of an aminofunctional poly(ethylene oxide-b-acrylate) (H2N-PEO-b-PAA) copolymer onto magnetite nanoparticles. The PEO blocks extended into aqueous media to keep the nanoparticles dispersed. Amines at the tips of the H2N-PEO corona were then linked through reaction with a PEO diacrylate oligomer to yield MBIClusters where the metal oxide in the precursor nanoparticles were distinctly separated by the hydrophilic polymer. The intensity average spacing between the magnetite nanoparticles within the clusters was estimated to be ~50 nm. These MBIClusters with hydrophilic intra-cluster space had transverse relaxivities (r2’s) that increased from 190 to 604 s−1 mM Fe−1 measured at 1.4 T and 37 °C as their average sizes increased. The clusters were loaded with up to ~38 wt% of the multi-cationic drug gentamicin. MRI scans focused on the livers of mice demonstrated that these MBIClusters are sensitive contrast agents.

Magnetic nanoparticles coated with polymers have existing and further potential for applications in medicine, including magnetic resonance imaging (MRI) imaging for diagnostics and assessing biodistribution, and their capacity to remotely generate heat in response to alternating current magnetic fields to elicit biological responses. Advances in such domains rely on developing better understanding of how such materials respond to magnetic fields. This paper reports thermosensitive properties of poly(N-isopropylacrylamide-co-Nile Red)-coated magnetic nanostructures upon passing through the lower critical solution temperature (LCST) of the polymer brush, and correlation of this behavior with formation of aggregates. Discrete magnetite nanoparticles coated with brush layers comprised of terminally attached poly(N-isopropylacrylamide-co-Nile Red) afforded highly water-dispersible nanoparticles (intensity average diameter of 38 nm) with good colloidal stability in phosphate buffers. The nanoparticles displayed enhanced transverse (T 2 ) NMR relaxometric behavior as the temperature was increased through the LCST. Moreover, incorporation of the environmentally sensitive Nile Red dye into the copolymer leads to significant changes in fluorescence emission intensity upon aggregation that present new possibilities for the remote fluorescence detection of aggregated structures.

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