溶剂效应和链转移效应对乙烯-醋酸乙烯酯共聚行为及支化结构的影响

基于溶液共聚法,制备出高醋酸乙烯酯含量和高分子量的乙烯-醋酸乙烯酯共聚物(EVM),研究了溶剂效应对乙烯-醋酸乙烯酯共聚行为和支化结构演化的影响,建立了基于链转移效应调控共聚物支化结构和相对分子质量的方法。研究结果显示,在醋酸乙烯酯(VAc)高转化率条件下,以链转移常数最低的叔丁醇为溶剂有利于提高EVM相对分子质量。进一步研究了叔丁醇中EVM分子链支化结构随聚合时间的演化规律,揭示出醋酸乙烯酯单元所含乙酰氧酯基为主要支化位点。其研究可为调控EVM分子结构、实现高性能EVM的工业化生产提供理论基础和实践参考。

Bacterial outer membrane vesicles-based therapeutic platform eradicates triple-negative breast tumor by combinational photodynamic/chemo-/immunotherapy

Bacterial outer membrane vesicles(OMVs)are potent immuno-stimulating agents and have the potentials to be bioengineered as platforms for antitumor nanomedicine.In this study,OMVs are demonstrated as promising antitumor therapeutics.OMVs can lead to beneficial M2-to-M1 polarization of macrophages and induce pyroptosis to enhance antitumor immunity,but the therapeutic window of OMVs is narrow for its toxicity.We propose a bioengineering strategy to enhance the tumor-targeting ability of OMVs by macrophage-mediated delivery and improve the antitumor efficacy by co-loading of photosensitizer chlorin e6(Ce6)and chemotherapeutic drug doxorubicin(DOX)into OMVs as a therapeutic platform.We demonstrate that systemic injection of the DOX/Ce6-OMVs@M therapeutic platform,providing combinational photodynamic/chemo-/immunotherapy,eradicates triple-negative breast tumors in mice without side effects.Importantly,this strategy also effectively prevents tumor metastasis to the lung.This OMVs-based strategy with bioengineering may serve as a powerful therapeutic platform for a synergic antitumor therapy.

Emerging vaccine nanotechnology: From defense against infection to sniping cancer

Looking retrospectively at the development of humanity, vaccination is an unprecedented medical landmark that saves lives by harnessing the human immune system. During the ongoing coronavirus disease 2019(COVID-19) pandemic, vaccination is still the most effective defense modality. The successful clinical application of the lipid nanoparticle-based Pfizer/BioNTech and Moderna mRNA COVID-19 vaccines highlights promising future of nanotechnology in vaccine development. Compared with conventional vaccines, nanovaccines are supposed to have advantages in lymph node accumulation,antigen assembly, and antigen presentation;they also have, unique pathogen biomimicry properties because of well-organized combination of multiple immune factors. Beyond infectious diseases, vaccine nanotechnology also exhibits considerable potential for cancer treatment. The ultimate goal of cancer vaccines is to fully mobilize the potency of the immune system as a living therapeutic to recognize tumor antigens and eliminate tumor cells, and nanotechnologies have the requisite properties to realize this goal.In this review, we summarize the recent advances in vaccine nanotechnology from infectious disease prevention to cancer immunotherapy and highlight the different types of materials, mechanisms, administration methods, as well as future perspectives.

Nanomaterials for radiotherapeutics-based multimodal synergistic cancer therapy

Over the past decade,numerous studies have attempted to enhance the effectiveness of radiotherapy(external beam radiotherapy and internal radioisotope therapy)for cancer treatment.However,the low radiation absorption coefficient and radiation resistance of tumors remain major critical challenges for radiotherapy in the clinic.With the development of nanomedicine,nanomaterials in combination with radiotherapy offer the possibility to improve the efficiency of radiotherapy in tumors.Nanomaterials act not only as radiosensitizers to enhance radiation energy,but also as nanocarriers to deliver therapeutic units in combating radiation resistance.In this review,we discuss opportunities for a synergistic cancer therapy by combining radiotherapy based on nanomaterials designed for chemotherapy,photodynamic therapy,photothermal therapy,gas therapy,genetic therapy,and immunotherapy.We highlight how nanomaterials can be utilized to amplify antitumor radiation responses and describe cooperative enhancement interactions among these synergistic therapies.Moreover,the potential challenges and future prospects of radio-based nanomedicine to maximize their synergistic efficiency for cancer treatment are identified.

Computational Investigation of the Interaction Between Hydrogen Atoms and an Intense Circularly Polarized Laser Field

The study of interactions between a high-power laser and atoms has been one of the fundamental and interesting topics in strong field physics for decades.Based on a nonperturbativemodel,ten years ago,we developed a set of programs to facilitate the study of interactions between a circularly polarized laser and atomic hydrogen.These programs included only contribution from the bound states of the hydrogen atom.However,as the laser intensity increases,contribution from continuum states to the excitation and ionization processes becomes larger and can no longer be neglected.Furthermore,because the original code is not able to add this contribution directly due to its many disadvantages,a major upgrade of the code is required before including the contribution from continuum states in future.In this paper,first we deduce some important formulas for contribution of continuum states and present modifications and tests for the upgraded code in detail.Second we show some comparisons among new results,old results from the original codes and the available experimental data.Overall the new result agrees with experimental data well.Last we present our calculation of above-threshold ionization(ATI)rate and compare it with a pertubative calculation.The comparison shows that our nonperturbative calculation can also produce ATI peak suppression.