Quantum dot-doped porous silicon metal–semiconductor metal photodetector

In this paper, we report on the enhancement of spectral photoresponsivity of porous silicon metal–semiconductor metal (PS-MSM) photodetector embedded with colloidal quantum dots (QDs) inside the pore layer. The detection efficiency of QDs/PS hybrid-MSM photodetector was enhanced by five times larger than that of the undoped PS-MSM photodetector. The bandgap alignment between PS (approximately 1.77 eV) and QDs (approximately 1.91 eV) facilitates the photoinduced electron transfer from QDs to PS whereby enhancing the photoresponsivity. We also showed that the photoresponsitivity of QD/PS hybrid-MSM photodetector depends on the number of layer coatings of QDs and the pore sizes of PS.Published versio

Development of PEGylated PLGA nanoparticle for controlled and sustained drug delivery in cystic fibrosis

<p>Abstract</p> <p>Background</p> <p>The mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene results in CF. The most common mutation, ΔF508-CFTR, is a temperature-sensitive, trafficking mutant with reduced chloride transport and exaggerated immune response. The ΔF508-CFTR is misfolded, ubiquitinated, and prematurely degraded by proteasome mediated- degradation. We recently demonstrated that selective inhibition of proteasomal pathway by the FDA approved drug PS-341 (pyrazylcarbonyl-Phe-Leuboronate, a.k.a. Velcade or bortezomib) ameliorates the inflammatory pathophysiology of CF cells. This proteasomal drug is an extremely potent, stable, reversible and selective inhibitor of chymotryptic threonine protease-activity. The apprehension in considering the proteasome as a therapeutic target is that proteasome inhibitors may affect proteostasis and consecutive processes. The affect on multiple processes can be mitigated by nanoparticle mediated PS-341 lung-delivery resulting in favorable outcome observed in this study.</p> <p>Results</p> <p>To overcome this challenge, we developed a nano-based approach that uses drug loaded biodegradable nanoparticle (PLGA-PEG^PS-341) to provide controlled and sustained drug delivery. The <it>in vitro </it>release kinetics of drug from nanoparticle was quantified by proteasomal activity assay from days 1-7 that showed slow drug release from day 2-7 with maximum inhibition at day 7. For <it>in vivo </it>release kinetics and biodistribution, these drug-loaded nanoparticles were fluorescently labeled, and administered to C57BL6 mice by intranasal route. Whole-body optical imaging of the treated live animals demonstrates efficient delivery of particles to murine lungs, 24 hrs post treatment, followed by biodegradation and release over time, day 1-11. The efficacy of drug release in CF mice (<it>Cftr^-/-</it>) lungs was determined by quantifying the changes in proteasomal activity (~2 fold decrease) and ability to rescue the <it>Pseudomonas aeruginosa </it>LPS (<it>Pa</it>-LPS) induced inflammation, which demonstrates the rescue of CF lung disease in murine model.</p> <p>Conclusion</p> <p>We have developed a novel drug delivery system to provide sustained delivery of CF "correctors" and "anti-inflammatories" to the lungs. Moreover, we demonstrate here the therapeutic efficacy of nano-based proteostasis-modulator to rescue <it>Pa-LPS </it>induced CF lung disease.</p

Aggregation-induced emission (AIE) dye loaded polymer nanoparticles for gene silencing in pancreatic cancer and their in vitro and in vivo biocompatibility evaluation

We have developed aggregation-induced emission (AIE) dye loaded polymer nanoparticles with deep-red emission for siRNA delivery to pancreatic cancer cells. Two US Food and Drug Administration (FDA) approved surfactant polymers, Pluronics F127 and PEGylated phospholipid, were used to prepare the dye-loaded nanoparticle formulations and they can be used as nanovectors for gene silencing of mutant K-ras in pancreatic cancer cells. The successful transfection of siRNA by the developed nanovectors was confirmed by the fluorescent imaging and quantified through flow cytometry. Quantitative real time polymerase chain reaction (PCR) indicates that the expression of the mutant K-ras oncogene from the MiaPaCa-2 pancreatic cancer cells has been successfully suppressed. More importantly, our in vivo toxicity study has revealed that both the nanoparticle formulations are highly biocompatible in BALC/c mice. Overall, our results suggest that the AIE dye-loaded polymer nanoparticle formulations developed here are suitable for gene delivery and have high potential applications in translational medicine research

Implantable MEMS drug delivery device for cancer radiation reduction

We present the first implantable MEMS drug delivery device that includes an electrochemical bellows pump, refillable drug reservoir, and dual regulation valve. Multiple drug pump configurations were fabricated, assembled, and tested. Delivery of agents for cancer radiation reduction was demonstrated. In vivo chronic delivery of radiation sensitizing agents in the form of small interfering (siRNA)-gold nanorod complexes (nanoplexes) directly to tumors induced in mice was achieved. Radiation therapy in conjunction with active drug pumping by electrolysis actuation resulted in significant reduction of colon cancer tumor (HT29) size (~50%) over diffusion-based delivery and intravenous injections. To our knowledge, this is the first MEMS drug delivery pump suitable for safe, efficacious, and local delivery of short half-life siRNA in vivo

Quantum Dots for Biophotonics

<p>This theme issue provides an excellent collection of reviews and original research articles on the study of various bioconjugated quantum dot formulations for diagnostics and therapy applications using biophotonic imaging and sensing approaches.</p

Effects of Low-Order Surface Vacancy on Extinction Spectra of Localized Surface Plasmon Resonance

In this study; we demonstrate the use of discrete dipole approximation (DDA) approach to estimate the influenced of low order surface vacancies on the localized surface plasmon resonance that is in the range of di-to squarevacancy. Gold rectangular nanoprism was chosen as a model for the simulation due to its recent unique surface plasmon resonance property. We have found that when the concentration of vacancy is kept in the lowest with unity in number, the apparent fluctuations in extinction spectra are observed and captured and the fluctuation is depending on the wavelength of incident light, the order of vacancy, and the arrangement of vacancy. Also, the agglomeration of vacancy enhances fluctuation behavior of the extinction spectra over the wavelength of interest. Diagonally arranged vacancy scatters light the most. Considering that most studies using DDA have only considered perfect nanoprisms in comparison with experimental results, this vacancy treatment might be an imminent factor to be included for future DDA calculations of plasmonic nanomaterials.open2

In vivo toxicity of quantum dots: no cause for concern?

Semiconductor nanocrystals, also known as quantum dots (QDs), possess unique optical properties that make them useful as fluorescent probes or traceable nanocarriers for in vivo applications ranging from imaging to theranostics. The surfaces of QDs can be conjugated with biomolecules to enable in vivo targeted imaging and drug delivery. These unique capabilities and qualities of QDs have made them a powerful platform that can help to reveal important biological insights. Ultimately, they may also provide unique benefits in clinical diagnostic and therapeutic applications. However, progress toward clinical applications has been delayed by concerns about the potential toxicity of QDs. Much of the QDs community has been hesitant to work toward clinical applications, based on reports demonstrating release of toxic heavy metal ions from degradation of QDs in cell culture studies. In addition, photoexcited QDs have been shown to generate reactive oxygen species that are highly toxic to cells. On the other hand, in small animal studies, bioconjugated QDs did not have any observable ill effects at concentrations appropriate for in vivo imaging applications. Thus, conclusions drawn from in vitro and in vivo studies remain somewhat contradictory and do not yet provide a sound basis for confident prediction of in vivo toxicity in humans