University of Southern California

About: University of Southern California is a education organization based out in Los Angeles, California, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 73160 authors who have published 169955 publications receiving 7838906 citations. The organization is also known as: USC & University of Southern CA.

Nanoparticle biointerfacing by platelet membrane cloaking

Abstract: Development of functional nanoparticles can be encumbered by unanticipated material properties and biological events, which can affect nanoparticle effectiveness in complex, physiologically relevant systems. Despite the advances in bottom-up nanoengineering and surface chemistry, reductionist functionalization approaches remain inadequate in replicating the complex interfaces present in nature and cannot avoid exposure of foreign materials. Here we report on the preparation of polymeric nanoparticles enclosed in the plasma membrane of human platelets, which are a unique population of cellular fragments that adhere to a variety of disease-relevant substrates. The resulting nanoparticles possess a right-side-out unilamellar membrane coating functionalized with immunomodulatory and adhesion antigens associated with platelets. Compared to uncoated particles, the platelet membrane-cloaked nanoparticles have reduced cellular uptake by macrophage-like cells and lack particle-induced complement activation in autologous human plasma. The cloaked nanoparticles also display platelet-mimicking properties such as selective adhesion to damaged human and rodent vasculatures as well as enhanced binding to platelet-adhering pathogens. In an experimental rat model of coronary restenosis and a mouse model of systemic bacterial infection, docetaxel and vancomycin, respectively, show enhanced therapeutic efficacy when delivered by the platelet-mimetic nanoparticles. The multifaceted biointerfacing enabled by the platelet membrane cloaking method provides a new approach in developing functional nanoparticles for disease-targeted delivery.

Oxygen and carbon isotope fractionation in biogenic aragonite: temperature effects

Abstract: To better interpret the isotopic composition of ancient aragonitic fossils, stable-isotopic analyses have been performed on live and modern specimens of aragonitic foraminifera, gastropods and scaphopods. Samples were collected from the continental margins off southern California and Texas, U.S.A., and Mexico, and provide a range in ambient temperature of 2.6–22.0°C. We observed a strong covariance between the δ18O of the aragonitic foraminifera Hoeglundina elegans and that of coeval aragonitic mollusks. On the average, Hoeglundina was 0.2 ± 0.2‰ depleted in 18O relative to the mollusks, and 0.6 ± 0.3‰ enriched relative to the calcitic foraminifera Uvigerina. This enrichment in 18O of aragonite relative to calcite is similar to that observed in previous experimental and theoretical studies. The temperature dependences of mollusk and Hoeglundina δ18O-values were not notably different from that previously determined for inorganically precipitated calcite, and no significant temperature dependence in Hoeglundina-Uvigerina18O fractionation was observed. Of note is the temperature dependence of the δ13C of the biogenic aragonite. Relative to the dissolved inorganic carbon (DIC), the δ13C of Hoeglundina and the mollusks decreased by 0.11 and 0.13‰, respectively, per °C increase in temperature. The temperature dependence in Hoeglundina-DIC 13C enrichment, and the lack of it in Uvigerina-DIC enrichment, accounts for the temperature dependence in Hoeglundina-Uvigerina (calcitic) fractionation noted by us and previous workers. Isotopic differences between coeval specimens of these genera provide a rough measure of paleotemperature without requiring a knowledge of the isotopic composition of the paleo-ocean.

The renaissance of black phosphorus

Abstract: One hundred years after its first successful synthesis in the bulk form in 1914, black phosphorus (black P) was recently rediscovered from the perspective of a 2D layered material, attracting tremendous interest from condensed matter physicists, chemists, semiconductor device engineers, and material scientists. Similar to graphite and transition metal dichalcogenides (TMDs), black P has a layered structure but with a unique puckered single-layer geometry. Because the direct electronic band gap of thin film black P can be varied from 0.3 eV to around 2 eV, depending on its film thickness, and because of its high carrier mobility and anisotropic in-plane properties, black P is promising for novel applications in nanoelectronics and nanophotonics different from graphene and TMDs. Black P as a nanomaterial has already attracted much attention from researchers within the past year. Here, we offer our opinions on this emerging material with the goal of motivating and inspiring fellow researchers in the 2D materials community and the broad readership of PNAS to discuss and contribute to this exciting new field. We also give our perspectives on future 2D and thin film black P research directions, aiming to assist researchers coming from a variety of disciplines who are desirous of working in this exciting research field.

Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

Abstract: Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head. It significantly improved both SNR for flow detection and connectivity of microvascular network when compared to other amplitude-decorrelation algorithms.