Carbon dots (CDs) with quantum yield up to 83% have been synthesized with a Mg/N double doping fluorescence-enhanced strategy. Besides N-mediated surface passivation by ethylenediamine, the Mgcitric acid chelate played the roles of introducing Mg and preserving the carboxyl group, both greatly contributing to the photoluminescence enhancement of the final CDs. Importantly, the N-and Mgdoping functioned in concert without mutual influence.

Pancreatic cancer, one of the most lethal human malignancies with dismal prognosis, is refractory to existing radio-chemotherapeutic treatment modalities. There is a critical unmet need to develop effective approaches, especially for targeted pancreatic cancer drug delivery. Targeted and drug-loaded nanoparticles (NPs) combined with ultrasound-mediated microbubble destruction (UMMD) have been shown to significantly increase the cellular uptake in vitro and drug retention in vivo, suggesting a promising strategy for cancer therapy. In this study, we synthesized pancreatic cancer-targeting organic NPs that were modified with anti CA19-9 antibody and encapsulated paclitaxol (PTX). The three-block copolymer methoxy polyethylene glycol-polylacticco-glycolic acid-polylysine (mPEG-PLGA-PLL) constituted the skeleton of the NPs. We speculated that the PTX-NPs-anti CA19-9 would circulate long-term in vivo, "actively target" pancreatic cancer cells, and sustainably release the loaded PTX while UMMD would "passively target" the irradiated tumor and effectively increase the permeability of cell membrane and capillary gaps. Our results demonstrated that the combination of PTX-NPs-anti CA19-9 with UMMD achieved a low IC50, significant cell cycle arrest, and cell apoptosis in vitro. In mouse pancreatic tumor xenografts, the combined application of PTX-NP-anti CA19-9 NPs with UMMD attained the highest tumor inhibition rate, promoted the pharmacokinetic profile by increasing AUC, t1/2, and mean residence time (MRT), and decreased clearance. Consequently, the survival of the tumor-bearing nude mice was prolonged without obvious toxicity. The dynamic change in cellular uptake, targeted real-time imaging, and the concentration of PTX in the plasma and tumor were all closely associated with the treatment efficacy both in vitro and in vivo. Our study suggests that PTX-NP-anti CA19-9 NPs combined with UMMD is a promising strategy for the treatment of pancreatic cancer.

SUMMARYLong-chain normal hydrocarbons (e.g. alkanes, alkenes and dienes) are rare biological molecules and their biosynthetic origins are obscure. Detailed analyses of the surface lipids that accumulate on maize silks have revealed that these hydrocarbons constitute a large portion (>90%) of the cuticular waxes that coat this organ, which contrasts with the situation on maize seedling leaves, where the cuticular waxes are primary alcohols and aldehydes. The normal hydrocarbons that occur on silks are part of a homologous series of alkanes, alkenes and dienes of odd-number carbon atoms, ranging between 19 and 33 in number. The alkenes and dienes consist of a homologous series, each of which has double bonds situated at defined positions of the alkyl chains: alkenes have double bonds situated at the sixth, ninth or 12th positions, and dienes have double bonds situated at the sixth and ninth, or ninth and twelfth positions. Finding a homologous series of unsaturated aldehydes and fatty acids suggests that these alkenes and dienes are biosynthesized by a series of parallel pathways of fatty-acid elongation and desaturation reactions, which are followed by sequential reduction and decarbonylation. In addition, the silk cuticular waxes contain metabolically related unsaturated long-chain methylketones, which probably arise via a decarboxylation mechanism. Finally, metabolite profiling analyses of the cuticular waxes of two maize inbred lines (B73 and Mo17), and their genetic hybrids, have provided insights into the genetic control network of these biosynthetic pathways, and that the genetic regulation of these pathways display best-parent heterotic effects.

A novel, neutral catalytic cycle for the synthesis of epoxides from carbony1 compounds and diazo compounds using catalytic quantities of transition metal salts and sulfides has been developed. In this catalytic cycle, the diazo compound is decomposed by the transition metal salt to give a metallocarbene, and this is picked up by the sulfide to give a sulfur ylide, which then reacts with the aldehyde to give an epoxide and returns the sulfide back into the catalytic cycle. To obtain good yields of epoxides it is necessary to maintain a low concentration of the diazo compound (by slow addition), otherwise dimerisation of the diazo compound is the dominant reaction. Factors