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Tumor microenvironment-induced ultrasmall nanodrug generation (TMIUSNG) is an unprecedented approach to overcome the drug penetration barriers across complex biological systems, poor circulation stability and limited drug loading efficiency (DLE). Herein, a novel strategy was designed to synthesize metal−organic nanodrug complexes (MONCs) through supramolecular coassembly of photosensitizer sinoporphyrin sodium, chemotherapeutic drug doxorubicin and ferric ions. Compared with the free photosensitizer, MONCs produced 3-fold more reactive oxygen species (ROS) through the energy transfer-mediated fluorescence quenching. Remarkably, the self-delivering supramolecular MONCs with high DLE acted as a potent ultrasmall-nanodrug generator in response to the mild acidic tumor microenvironment to release ultrasmall nanodrugs (5− 10 nm in diameter) from larger parental nanoparticles (140 nm in diameter), which in turn enhanced the intratumor permeability and therapeutic efficacy. The key mechanism of MONC synthesis was proposed, and we, for the first time, validated the generation of supramolecular scaffold intermediates between MONCs' assembly/disassembly states, as well as their involvement in multidrug ligands interactions. This proof-of-concept TMIUSNG strategy provides a foundation for the rational design of analogous carrier-free nanotheranostics through the combination of multiple therapeutic agents and metal ions with imaging functions.

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The nonisothermal crystallization behaviors of poly(lactic acid) (PLA) under ambient N2 and compressed CO2 (5−50 bar) at cooling rates of 0.2−2.0 °C/min were carefully studied using high-pressure differential scanning calorimetry. The presence of compressed CO2 postponed the crystallization peak to a lower temperature region while effectively reducing the half-crystallization time and enhancing the crystallinity of the PLA specimen. On the basis of these findings, a new foaming strategy was proposed and utilized to fabricate PLA foams using the ordinary unmodified PLA. The upper and lower temperature limits of this foaming strategy were 105 and 90 °C, which were determined by the melt strength and crystallization behavior of the unmodified PLA specimen, respectively. In this temperature range, PLA foams with interconnected structures, porosity of 67.9−91.4%, and expansion ratio of 15−30 times are controllably produced. The obtained PLA foams have widely distributed average bubble size of 80−270 μm and CO2 enhanced crystallinity of 32−38%.

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The alkylation kinetics of isobutane with butene using sulfuric acid as catalyst was investigated by batch experiments in the conditions of industrial interest. More than 16 alkylates were identified and quantified by GC-MS. On the basis of the classic carbonium ion mechanism, the kinetic model was established, which can predict the concentration change of three groups of key alkylates including trimethylpentanes (TMPs), undesirable dimethylhexanes (DMHs), and heavy ends (HEs). The agreement between experimental and model calculated data was quite satisfactory. The rate constants were found to be constant with the varied temperatures (276.2 to 285.2 K) except those accounting for the addition of H+ to isobutene and its reversible reaction. An anti-Arrhenius behavior was observed for the addition reaction of H+ to isobutene, in which the corresponding rate constant falls with the increasing temperatures. The kinetic model was confirmed by the simulation of the industrial alkylation reactor. Hopefully, the kinetic model developed in this work will be useful to the design and optimization of novel alkylation reactors.

A stereodivergent Pd/Cu catalyst system has been developed for the unprecedented dynamic kinetic asymmetric transformation (DyKAT) of racemic unsymmetrical 1,3-disubstituted allylic acetates with prochiral aldimine esters. A series of α,αdisubstituted α-amino acids bearing vicinal stereocenters were easily prepared with excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to >20:1 dr). Moreover, all four stereoisomers of the product can be readily obtained simply by switching the configurations of the two chiral metal catalysts. Furthermore, the present work highlights the power of synergistic Pd/ Cu catalysis consisting of two common bidentate chiral ligands for stereodivergent synthesis.