Biodegradable poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) have been widely used as delivery vehicles for chemotherapy drugs. However, premature drug release in PLGA NPs can damage healthy tissue and cause serious adverse effects during systemic administration. Here, we report a tannic acid− Fe(III) (Fe III −TA) complex-modified PLGA nanoparticle platform (DOX-TPLGA NPs) for the tumor-targeted delivery of doxorubicin (DOX). A PEGylated-PLGA inner core and Fe III −TA complex outer shell were simultaneously introduced to reduce premature drug release in blood circulation and increase pH-triggered drug release in tumor tissue. Compared to the unmodified NPs, the initial burst rate of DOX-TPLGA NPs was significantly reduced by nearly 2-fold at pH 7.4. Moreover, the cumulative drug release rate at pH 5.0 was 40% greater than that at pH 7.4 due to the pH-response of the Fe III −TA complex. Cellular studies revealed that the TPLGA NPs had enhanced drug uptake and superior cytotoxicity of breast cancer cells in comparison to free DOX. Additionally, the DOX-TPLGA NPs efficiently accumulated in the tumor site of 4T1-bearing nude mice due to the enhanced permeability and retention (EPR) effect and reached a tumor inhibition rate of 85.53 ± 8.77% (1.31-fold versus DOX-PLGA NPs and 3.12-fold versus free DOX). Consequently, the novel TPLGA NPs represent a promising delivery platform to enhance the safety and efficacy of chemotherapy drugs.
Switching can be performed with multiple physical dimensions of an optical signal. Previously optical switching was mainly focused in the wavelength domain. In this paper we discuss the general architecture of integrated silicon photonic switches by exploiting multi-dimensions in wavelength, polarization, and mode. To route a data channel from one input port to an arbitrary output port in a network node, three basic functions are required: de-multiplexing, switching, and multiplexing. The multiplexing and de-multiplexing processes can be realized in any one physical dimension. The capacity of a switch can be effectively scaled by using joint physical dimensions. As two examples, we first present a wavelength switch based on dual-nanobeam cavities with high quality factors, a low power consumption, and a compact footprint. We then propose a design of a mode-polarization-wavelength selective switch by leveraging three physical dimensions, and experimentally demonstrate the building blocks and key functionalities.
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