CsPbBr3 and other perovskite semiconductors are rapidly emerging as strong competitors to TlBr and CZT, both in terms of innate properties and potentially significantly lower production cost. These crystals can be grown from the solution as well as melt. However, there has been very few studies on understanding the effects of bandgap and crystalline defects, polarization, stoichiometry and other growth parameters on the charge transport properties and detector reproducibility. In this study, we will report on these interconnected parameters for CsPbBr3 gamma detectors grown by the Bridgman technique.
We utilized these NIR QDs to demonstrate the utility of an image processing algorithm capable of determining the relative concentration ratios of two distinct emitters at various tissue depths. This algorithm is based on the dual probe imaging method, which we modified for use in wide-field imaging systems. The algorithm was validated using skin-mimicking tissue phantoms that were used to vary the effective imaging depth from 0-1.2 mm. The algorithm correctly determined concentration ratios of a two-color QD system for variations in concentration ≥ 10%, independently of depth. These contrast agents and the imaging approach are being adapted for use for in vivo targeted tumor imaging.ng adapted for use for in vivo targeted tumor imaging.
For the first time, we assess the biodistribution and toxicity of unshelled CIS and partially zinc-alloyed CISZ QDs in a murine model at 1-day, 7-day, and 1-month timepoints. We show that bare CIS QDs breakdown quickly, with >75% of the initial dose being cleared by 1-month. Surprisingly, we also demonstrate a significant toxic response to these QDs as measured by organ weight, blood chemistry, and histology. Specifically, low doses of CIS particles (15mg/kg) induce severe hepatotoxicity and splenotoxicity. Similarly, CISZ demonstrated significant, but lower, toxicity compared to bare CIS. Overall, our data suggests that reconsideration of CIS as a translatable QD system is required: degradation-based toxicity is an important aspect of biocompatibility that needs to be assessed in “non-toxic” QDs, if QDs are to ever be clinically successful. Finally, we suggest a non-toxic biodegradable alternative.
Semiconductor quantum dots (QDs) have great potential for multiplexed imaging and biosensing applications. Due to the quantum confinement effect, spectral tuning of the emission color of these nanocrystals is made possible through changing their size. However, QDs of different emission colors are dissimilar in their brightness values, defined as the product of molar extinction coefficient (ε) and quantum yield (QY). These differences arise from extinction coefficients which are coupled to the number of atoms and bonds constituting the QD. As a consequence, the relative brightness of QDs can be orders of magnitude higher for larger, red emitting QDs compared to their smaller blue/green emitting counterparts even with comparable QYs. This study addresses this problem by drawing a quantitative comparison of absorption properties of different type-I InP QDs, aiming to make these heterostructures suitable for accurate imaging and sensing applications. Tuning of the absorption cross-section and extinction coefficients, along with brightness tuning of the QDs has been performed through synthesizing a series of QDs with a combination of core sizes, shell thicknesses, and compositions.
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