Figure 5. (a) Directly using the β-CD/PTX complex to form biodegradable capsules. Reprinted with permission from ref 153.

No abstract

Multifunctional mesoporous silica nanoparticles are developed in order to deliver anticancer drugs to specifi c cancer cells in a targeted and controlled manner. The nanoparticle surface is functionalized with amino-β -cyclodextrin rings bridged by cleavable disulfi de bonds, blocking drugs inside the mesopores of the nanoparticles. Poly(ethylene glycol) polymers, functionalized with an adamantane unit at one end and a folate unit at the other end, are immobilized onto the nanoparticle surface through strong β -cyclodextrin/adamantane complexation. The non-cytotoxic nanoparticles containing the folate targeting units are effi ciently trapped by folate-receptor-rich HeLa cancer cells through receptor-mediated endocytosis, while folate-receptor-poor human embryonic kidney 293 normal cells show much lower endocytosis towards nanoparticles under the same conditions. The nanoparticles endocytosed by the cancer cells can release loaded doxorubicin into the cells triggered by acidic endosomal pH. After the nanoparticles escape from the endosome and enter into the cytoplasm of cancer cells, the high concentration of glutathione in the cytoplasm can lead to the removal of the β -cyclodextrin capping rings by cleaving the pre-installed disulfi de bonds, further promoting the release of doxorubicin from the drug carriers. The high drug-delivery effi cacy of the multi functional nanoparticles is attributed to the co-operative effects of folatemediated targeting and stimuli-triggered drug release. The present delivery system capable of delivering drugs in a targeted and controlled manner provides a novel platform for the next generation of therapeutics.

Biomedical applications of nontoxic amorphous calcium carbonate (ACC) nanoparticles have mainly been restricted because of their aqueous instability. To improve their stability in physiological environments while retaining their pH-responsiveness, a novel nanoreactor of ACC-doxorubicin (DOX)@silica was developed for drug delivery for use in cancer therapy. As a result of its rationally engineered structure, this nanoreactor maintains a low drug leakage in physiological and lysosomal/endosomal environments, and responds specifically to pH 6.5 to release the drug. This unique ACC-DOX@silica nanoreactor releases DOX precisely in the weakly acidic microenvironment of cancer cells and results in efficient cell death, thus showing its great potential as a desirable chemotherapeutic nanosystem for cancer therapy.

X-ray spectra following radiative recombination of free electrons with bare uranium ions (U92+) were measured at the electron cooler of the ESR storage ring. The most intense lines observed in the spectra can be attributed to the characteristic Lyman ground-state transitions and to the recombination of free electrons into the K shell of the ions. Our experiment was carried out by utilizing the deceleration technique which leads to a considerable reduction of the uncertainties associated with Doppler corrections. This, in combination with the 0 degree observation geometry, allowed us to determine the ground-state Lamb shift in hydrogenlike uranium (U91+) from the observed x-ray lines with an accuracy of 1%. The present result is about 3 times more precise than the most accurate value available up to now and provides the most stringent test of bound-state quantum electrodynamics for one-electron systems in the strong-field regime.

Covalent organic frameworks (COFs) are excellent candidates for various applications. So far, successful methods for the constructions of COFs have been limited to a few condensation reactions based on only one type of covalent bond formation. Thus, the exploration of a new judicious synthetic strategy is a crucial and emergent task for the development of this promising class of porous materials. Here, we report a new orthogonal reaction strategy to construct COFs by reversible formations of two types of covalent bonds. The obtained COFs consisting of multiple components show high surface area and high H2 adsorption capacity. The strategy is a general protocol applicable to construct not only binary COFs but also more complicated systems in which employing regular synthetic methods did not work.

Squaraine dyes were loaded inside mesoporous silica nanoparticles, and the nanoparticle surfaces were then wrapped with ultrathin graphene oxide sheets, leading to the formation of a novel hybrid material. The hybrid exhibits remarkable stability and can efficiently protect the loaded dye from nucleophilic attack. The biocompatible hybrid is noncytotoxic and presents significant potential for application in fluorescence imaging in vitro.

A series of semiconducting polymer dots (Pdots) composed of phosphorescent Ir(III) complexes and polyfluorene units in the main polymer chains are designed, synthesized, and applied in ratiometric oxygen sensing and photodynamic cancer therapy. The ultrasmall Pdots with particle size less than 10 nm are fabricated in aqueous solution on account of amphiphilic nature of the polymers. The Pdots possess fine photostability, biocompatibility, and efficient energy transfer from the polymer main chain to the Ir(III) complex. By utilizing the excited‐state energy transfer from phosphorescent Pdots to the ground state molecular oxygen, these Pdots are applied in the optical sensing of oxygen with ratiometric and naked‐eye detection as well as high sensitivity in aqueous solution. The Pdots also show low cytotoxicity and can pass across the cell membrane to enter into the cytoplasm. The singlet oxygen photo‐generated from the Pdots under irradiation at 488 nm can effectively induce the apoptosis and death of tumor cells for photodynamic cancer therapy in vitro.