A principal goal of cancer nanomedicine is to deliver therapeutics effectively to cancer cells within solid tumors. However, there are a series of biological barriers that impede nanomedicine from reaching target cells. Here, we report a stimuli-responsive clustered nanoparticle to systematically overcome these multiple barriers by sequentially responding to the endogenous attributes of the tumor microenvironment. The smart polymeric clustered nanoparticle (iCluster) has an initial size of ∼100 nm, which is favorable for long blood circulation and high propensity of extravasation through tumor vascular fenestrations. Once iCluster accumulates at tumor sites, the intrinsic tumor extracellular acidity would trigger the discharge of platinum prodrug-conjugated poly(amidoamine) dendrimers (diameter ∼5 nm). Such a structural alteration greatly facilitates tumor penetration and cell internalization of the therapeutics. The internalized dendrimer prodrugs are further reduced intracellularly to release cisplatin to kill cancer cells. The superior in vivo antitumor activities of iCluster are validated in varying intractable tumor models including poorly permeable pancreatic cancer, drug-resistant cancer, and metastatic cancer, demonstrating its versatility and broad applicability.nanomedicine | particle size | tumor penetration | tumor extracellular pH | stimuli responsive

The vast difference in timescale of carrier transport detected in perovskite solar cells is associated with different kinetics processes involving electron, defects and large cations, which determines the device performance and I–V hysteresis.

Lead (Pb) free non-toxic perovskite solar cells have become more important in the commercialization of the photovoltaic devices. In this study the structural, electronic, optical and mechanical properties of Pb-free inorganic metal halide cubic perovskites CsBX 3 (B = Sn, Ge; X = I, Br, Cl) for perovskite solar cells are simulated using first-principles Density Functional Theory (DFT). These compounds are semiconductors with direct band gap energy and mechanically stable. Results suggest that the materials have high absorption coefficient, low reflectivity and high optical conductivity with potential application in solar cells and other optoelectronic energy devices. On the basis of the optical properties, one can expect that the Germanium (Ge) would be a better replacement of Pb as Ge containing compounds have higher optical absorption and optical conductivity than that of Pb containing compounds. A combinational analysis of the electronic, optical and mechanical properties of the compounds suggests that CsGeI 3 based perovskite is the best Pb-free inorganic metal halide semiconductor for the solar cell application. However, the compound with solid solution of CsGe(I 0.7 Br 0.3 ) 3 is found to be mechanically more ductile than CsGeI 3 . This study will also guide to obtain Pb-free organic perovskites for optoelectronic devices.Recently, metal halide perovskites have drawn a great attention in the scientific community 1-11 due to their remarkable performance in solar cells thanks to their outstanding opto-electronic properties such as tunable bandgap, high optical absorption, broad absorption spectrum, small carrier effective masses, dominant point defect, long charge diffusion lengths and high charge carrier mobility 1,3 . In addition to this, these materials are abundant in nature and inexpensive. As a result solar cells based on these materials would be cheaper and more efficient than silicon-based photovoltaic (PV) technology 1 . Because of these extraordinary properties, this group of semiconductors have the potential to be used in a wide range of electronic devices beyond solar cells such as light emitting diodes, photodetector and solar-to-fuel energy conversion devices [8][9][10][11] . To predict a specific device application and improvements, a deeper and fundamental understanding the properties of the semiconductors is necessary. Therefore, studying the electronic, optical and mechanical properties as well as understanding the overall characteristics of the system is utmost important.Metal halide perovskite materials can be described by the general formula ABX 3 , where A is a cation, B is a metal ion and X is a halogen anion. In the last few years, different properties of metal halide perovskites have been reported for single or group of compounds (see Supplementary Section "Literature Review") to be used in solar cells after the discovery of organic perovskites 12 . Most of the perovskite compounds with high performance contain lead (Pb) which is toxic and undesirable. Herein, we have considered Pb-f...

The electron collection efficiency in dye-sensitized solar cells (DSCs) is usually related to the electron diffusion length, L = (Dτ)1/2, where D is the diffusion coefficient of mobile electrons and τ is their lifetime, which is determined by electron transfer to the redox electrolyte. Analysis of incident photon-to-current efficiency (IPCE) spectra for front and rear illumination consistently gives smaller values of L than those derived from small amplitude methods. We show that the IPCE analysis is incorrect if recombination is not first-order in free electron concentration, and we demonstrate that the intensity dependence of the apparent L derived by first-order analysis of IPCE measurements and the voltage dependence of L derived from perturbation experiments can be fitted using the same reaction order, γ ≈ 0.8. The new analysis presented in this letter resolves the controversy over why L values derived from small amplitude methods are larger than those obtained from IPCE data.