The rapid growth of organic–inorganic
hybrid perovskite
materials (such as methylammonium lead triiodide, MAPbI3) in photoelectric applications has prompted investigations of novel
strategies to improve photodetection performance. Although a few surface
nanofabrication methods have been applied to texture perovskite thin
films to enhance light trapping, it remains challenging to pattern
large-area periodic perovskite nanoarrays in a tunable and scalable
manner. In this work, we report a facile and low-cost approach to
fabricate large-area SiO2/Si nanopyramids arrays through
nanosphere lithography. These nanopyramids arrays are used to pattern
MAPbI3 thin films. We find that the introduction of nanopyramid
arrays enhances the light intensity within the perovskite film, which
is confirmed by light absorption tests and optical simulations. As
a result, the photodetectors based on MAPbI3 with nanopyramid
structures show excellent responsivity of 28.8 ± 1.0 A/W and
detectivity of (3.5 ± 0.1) × 1011 Jones at 650
nm. The photoresponse of the photodetector to pulsed light is highly
stable and reproducible, with rise and decay times of ∼0.7
and 1.1 ms, respectively. They also have a broader light sensitivity
range from ultraviolet to infrared light, i.e., 340 nm to 1100 nm,
compared to those without nanostructures. Finally, we demonstrate
a prototype image sensor using these photodetector arrays.
MicroRNA (miRNA) therapeutics are a promising cancer treatment approach with high efficacy and low side effects. Although substantial progress regarding pharmacokinetics and pharmacodynamics of miRNAs is made, it remains challenging for effective and harmless intracellular delivery. In this study, instant and efficient intracellular delivery of miRNA against esophageal cancer via photothermal effects induced on plasmonic pyramid arrays is reported. An instantaneous high temperature can be generated (≈470 °C) on a plasmonic pyramid after laser stimulation (≈8 μs @640 nm), which is enough to disrupt the cell membranes to facilitate intracellular delivery of biocargos like miRNA. Within ≈150 μs after removal of laser stimulation, the pyramid temperature would decrease to ≈37 °C to avoid cell damage. By this approach, intracellularly delivery of miRNA‐185 to Taxol‐resistance esophageal cancer cells is successfully achieved within minutes with decent delivery efficiency (64%) and cell viability (>95%) are observed after optimization. Moreover, for combating drug resistance, 61.9% of KYSE30/Taxol cell is inhibited after laser‐stimulation via the combined effects of miR‐185 and Taxol with efficient intracellular delivery. This study provides a convenient intracellular delivery approach for large biocargos and a possible solution for overcoming cancer drug resistance.
Mechanical cues are widely used for regulating cell behavior because of their overarching, extensive, and non-invasive advantages. However, unlike chemical cues, mechanical cues are not efficient enough to determine cell fate independently and improving the mechanosensitivity of cells is rather challenging. In this study, the combined effect of chemical and mechanical cues on the osteogenic differentiation of human mesenchymal stem cells is examined. These results show that chemical cues such as the presence of an osteogenic medium, induce cells to secrete more collagen, and induce integrin for recruiting focal adhesion proteins that mature and cascade a series of events with the help of the mechanical force of the scaffold material. High-resolution, highly ordered hollow-micro-frustum-arrays using double-layer lithography, combined with modified methacrylate gelatin loaded with pre-defined soluble chemicals to provide both chemical and mechanical cues to cells. This approach ultimately facilitates the achievement of cellular osteodifferentiation and enhances bone repair efficiency in a model of femoral fracture in vivo in mice. Moreover, the results also reveal these pivotal roles of Integrin 𝜶2/Focal adhesion kinase/Ras homolog gene family member A/Large Tumor Suppressor 1/Yes-associated protein in human mesenchymal stem cells osteogenic differentiation both in vitro and in vivo. Overall, these results show that chemical cues enhance the microtopographical sensitivity of cells.
In this work, we
report a hybrid lithographic method that combines
the top–down soft lithography and the bottom–up hydrothermal
approach for growing single-crystalline TiO
2
nanorod arrays
with arbitrary patterns. The arbitrary patterns of TiO
2
seeds were obtained through the microcontact printing of the TiO
2
seed precursor onto Si substrates using prepatterned poly(dimethylsiloxane)
(PDMS) as stamps, followed by a baking process. Afterward, TiO
2
nanorod arrays were selectively grown on patterned TiO
2
seeds through conventional hydrothermal methods. By controlling
the TiO
2
seed precursor concentration, the hydrothermal
reaction time and temperature and the patterns, the morphology and
density of the TiO
2
nanorods can be tuned in a controllable
manner. Overall, this work provides a new strategy for the low-cost
and facile preparation of patterned TiO
2
nanorod arrays
that has potential applications in micro–nano-optoelectronic
devices and other fields.
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