Tumor extracellular matrix (ECM) represents a major obstacle to the diffusion of therapeutics and drug delivery systems in cancer parenchyma. This biological barrier limits the efficacy of promising therapeutic approaches including the delivery of siRNA or agents intended for thermoablation. After extravasation due to the enhanced penetration and retention effect of tumor vasculature, typical nanotherapeutics are unable to reach the nonvascularized and anoxic regions deep within cancer parenchyma. Here, we developed a simple method to provide mesoporous silica nanoparticles (MSN) with a proteolytic surface. To this extent, we chose to conjugate MSN to Bromelain (Br–MSN), a crude enzymatic complex, purified from pineapple stems, that belongs to the peptidase papain family. This surface modification increased particle uptake in endothelial, macrophage, and cancer cell lines with minimal impact on cellular viability. Most importantly Br–MSN showed an increased ability to digest and diffuse in tumor ECM in vitro and in vivo.
Colloidal semiconductor quantum wells have emerged as a promising material platform for use in solution-processable lasers. However, applications relying on their optical gain suffer from nonradiative Auger decay due to multi-excitonic nature of light amplification in II-VI semiconductor nanocrystals. Here, we show sub-single exciton level of optical gain threshold in specially engineered CdSe/CdS@CdZnS core/crown@gradient-alloyed shell quantum wells. This sub-single exciton ensemble-averaged gain threshold of (Ng)≈ 0.84 (per particle) resulting from impeded Auger recombination, along with a large absorption cross-section of quantum wells, enables us to observe the amplified spontaneous emission starting at an ultralow pump fluence of ~ 800 nJ cm−2, at least three-folds better than previously reported values among all colloidal nanocrystals. Finally, using these gradient shelled quantum wells, we demonstrate a vertical cavity surface-emitting laser operating at a low lasing threshold of 7.5 μJ cm−2. These results represent a significant step towards the realization of solution-processable electrically-driven colloidal lasers.
Solution-processed type-II quantum wells exhibit outstanding optical properties, which make them promising candidates for light-generating applications including lasers and LEDs. However, they may suffer from poor colloidal stability under ambient conditions and show strong tendency to assemble into face-to-face stacks. In this work, to resolve the colloidal stability and uncontrolled stacking issues, we proposed and synthesized CdSe/CdSe 1−x Te x /CdS core/multicrown heteronanoplatelets (NPLs), controlling the amount of Te up to 50% in the crown without changing their thicknesses, which significantly increases their colloidal and photostability under ambient conditions and at the same time preserving their attractive optical properties. Confirming the final lateral growth of CdS sidewalls with X-ray photoelectron spectroscopy, energy-dispersive analysis, and photoelectron excitation spectroscopy, we found that the successful coating of this CdS crown around the periphery of conventional type-II NPLs prevents the unwanted formation of needle-like stacks, which results in reduction of the undesired scattering losses in thin-film samples of these NPLs. Owing to highly efficient exciton funneling from the outmost CdS crown accompanied by the reduced scattering and very low waveguide loss coefficient (∼18 cm −1), ultralow optical gain thresholds of multicrown type-II NPLs were achieved to be as low as 4.15 μJ/cm 2 and 2.48 mJ/cm 2 under one-and two-photon absorption pumping, respectively. These findings indicate that the strategy of using engineered advanced heterostructures of nanoplatelets provides solutions for improved colloidal stability and enables enhanced photonic performance.
Solution processed semiconductor lasers have achieved much success across the nanomaterial research community, including in organic semiconductors 1 , 2 , perovskites 3 , 4 and colloidal semiconductor nanocrystals 5 , 6 . The ease of integration with other photonic components, and the potential for upscaling using emerging large area fabrication technologies, such as roll-to-roll 7 , make these lasers attractive as low-cost photonic light sources that can find use in a variety of applications: integrated photonic circuitry 8 , 9 , telecommunications 10 , 11 , chemo-/bio-sensing 12 , 13 , security 14 , and lab-on-chip experiments 15 . However, for fiber-optic or free-space optical (FPO) communications and eye-safe LIDAR applications, room temperature solution-processed lasers have remained elusive. Here we report the first solution processed laser, comprising PbS colloidal quantum dots (CQDs) integrated on a distributed feedback (DFB) cavitiy, with tuneable lasing wavelength from 1.55 μm – 1.65 μm. These lasers operate at room temperature and exhibit linewidths as low as ~0.9 meV.
Biomimetic nanovesicles deriving from leukocytes membrane proteins, called leukosomes, exhibit increased targeting of cancer vasculature and stroma by exploiting the inflammatory pathway responsible for recruiting immune cells to the cancer lesion.
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