24 research outputs found
Photoresponse of Natural van der Waals Heterostructures
Van der Waals (vdW) heterostructures consisting of two dimensional materials
offer a platform to obtain material by design and are very attractive owing to
novel electronic states. Research on 2D van der Waals heterostructures (vdWH)
has so far been focused on fabricating individually stacked atomically thin
unary or binary crystals. Such systems include graphene (Gr), hexagonal boron
nitride (h-BN) and member of the transition metal dichalcogenides family. Here
we present our experimental study of the opto-electronic properties of a
naturally occurring vdWH, known as Franckeite, which is a complex layered
crystal composed of lead, tin, antimony, iron and sulfur. We present here that
thin film franckeite (60 nm < d < 100 nm) behave as narrow band gap
semiconductor demonstrating a wide band photoresponse. We have observed the
band-edge transition at ~ 1500 nm (~830 meV) and high external quantum
efficiency (EQE~3%) at room temperature. Laser power resolved and temperature
resolved photocurrent measurements reveal that the photo-carrier generation and
recombination are dominated by continuously distributed trap states within the
band gap. To understand wavelength resolved photocurrent, we also calculated
the optical absorption properties via density functional theory. Finally, we
have shown that the device has fast photoresponse with rise time as fast as ~ 1
ms. Our study provides a fundamental understanding of the optoelectronic
behavior in a complex naturally occurring vdWH and can open up the
possibilities of producing new type of nanoscale optoelectronic devices with
tailored properties.Comment: 10 pages, 5 figures (to be appeared in ACS NANO
WZB117 Decorated Metformin-Carboxymethyl Chitosan Nanoparticles for Targeting Breast Cancer Metabolism
The “Warburg effect” provides a novel method for treating cancer cell metabolism. Overexpression of glucose transporter 1 (GLUT1), activation of AMP-activated protein kinase (AMPK), and downregulation of mammalian target of rapamycin (mTOR) have been identified as biomarkers of abnormal cancer cell metabolism. Metformin (MET) is an effective therapy for breast cancer (BC), but its efficacy is largely reliant on the concentration of glucose at the tumor site. We propose a WZB117 (a GLUT1 inhibitor)-OCMC (O-carboxymethyl-chitosan)-MET combo strategy for simultaneous GLUT1 and mTOR targeting for alteration of BC metabolism. WZB117 conjugated polymeric nanoparticles were 225.67 ± 11.5 nm in size, with a PDI of 0.113 ± 0.16, and an encapsulation of 72.78 6.4%. OCMC pH-dependently and selectively releases MET at the tumor site. MET targets the mTOR pathway in cancer cells, and WZB117 targets BCL2 to alter GLUT1 at the cancer site. WZB117-OCMC-MET overcomes the limitations of MET monotherapy by targeting mTOR and BCL2 synergistically. WZB117-OCMC-MET activates AMPK and suppresses mTOR in a Western blot experiment, indicating growth-inhibitory and apoptotic characteristics. AO/EB and the cell cycle enhance cellular internalization as compared to MET alone. WZB117-OCMC-MET affects cancer cells’ metabolism and is a promising BC therapeutic strategy
Redox responsive xylan-SS-curcumin prodrug nanoparticles for dual drug delivery in cancer therapy
Nanoporous Sodium Carboxymethyl Cellulose-g-poly (Sodium Acrylate)/FeCl3 Hydrogel Beads: Synthesis and Characterization
Novel sodium carboxymethyl cellulose-g-poly (sodium acrylate)/Ferric chloride (CMC-g-PNaA/FeCl3) nanoporous hydrogel beads were prepared based on the ionic cross-linking between CMC-g-PNaA and FeCl3. The structure of CMC and CMC-g-PNaA were elucidated by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, and the elemental composition was analyzed by energy dispersive X-ray analysis (EDX). The physicochemical properties of the CMC-g-PNaA/FeCl3 hydrogel beads were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). The swelling percentage of hydrogel beads was studied at different time periods. The obtained CMC-g-PNaA/FeCl3 hydrogel beads exhibited a higher nanoporous morphology than those of CMC-g-PNaA and CMC beads. Furthermore, an AFM image of the CMC-g-PNaA/FeCl3 beads shows granule type topology. Compared to the CMC-g-PNaA (189 °C), CMC-g-PNaA/FeCl3 hydrogel beads exhibited improvement in thermal stability (199 °C). Furthermore, CMC-g-PNaA/FeCl3 hydrogel beads depicted a higher swelling percentage capacity of around 1452%, as compared to CMC-g-PNaA (1096%). Moreover, this strategy with preliminary results could be useful for the development of polysaccharide-based hybrid hydrogel beads for various potential applications