Beyond Antibiotics:Photo/Sonodynamic Approaches for Bacterial Theranostics

Rapid evolution and propagation of multidrug resistance among bacterial pathogens are outpacing the development of new antibiotics,but antimicrobial photodynamic therapy(aPDT)provides an excellent alternative.This treatment depends on the interaction between light and photoactivated sensitizer to generate reactive oxygen species(ROS),which are highly cytotoxic to induce apoptosis in virtually all microorganisms without resistance concern.When replacing light with low-frequency ultrasonic wave to activate sensitizer,a novel ultrasounddriven treatment emerges as antimicrobial sonodynamic therapy(aSDT).Recent advances in aPDT and aSDT reveal golden opportunities for the management of multidrug resistant bacterial infections,especially in the theranostic application where imaging diagnosis can be accomplished facilely with the inherent optical characteristics of sensitizers,and the generated ROS by aPDT/SDT cause broad-spectrum oxidative damage for sterilization.In this review,we systemically outline the mechanisms,targets,and current progress of aPDT/SDT for bacterial theranostic application.Furthermore,potential limitations and future perspectives are also highlighted.

Cytotoxic effect and possible mechanisms of Tetracaine on human corneal epithelial cells in vitro

AIM： To demonstrate the cytotoxic effect and possible mechanisms of Tetracaine on human corneal epithelial（HCEP） cells in vitro.·METHODS： In vitro cultured HCEP cell were treated with Tetracaine hydrochloride at different doses for different times, and their morphology, viability, and plasma membrane permeability were detected by light microscopy, methyl thiazolyl tetrazolium（MTT） assay,and acridine orange（AO）/ethidium bromide（EB） staining,respectively. Their cell cycle progression, phosphati-dylserine orientation in plasma membrane, and mitochondrial membrane potential（MTP） were assessed by flow cytometry. DNA fragmentation, ultrastructure,caspase activation, and the cytoplasmic apoptosis inducing factor（AIF） and cytochrome c（Cyt. c） along with the expression of B-cell lymphoma-2（Bcl-2） family proteins were examined by gel electrophoresis,transmission electron microscope, enzyme linked immunosorbent assay（ELISA）, and Western blot,respectively.·RESULTS： After exposed to Tetracaine at doses from10.0 to 0.3125 g/L, the HCEP cells showed dose- and time-dependent morphological abnormality and typical cytopathic effect, viability decline, and plasma membrane permeability elevation. Tetracaine induced phosphati-dylserine externalization, DNA fragmentation, G1 phase arrest, and ultrastructural abnormality and apoptotic body formation. Furthermore, Tetracaine at a dose of0.3125 g/L also induced caspase-3,-9 and-8 activation,MTP disruption, up-regulation of the cytoplasmic amount of Cyt. c and AIF, the expressions of Bax and Bad, and down-regulation of the expressions of Bcl-2 and Bcl-x L.·CONCLUSION： Tetracaine above 0.3125 g/L（1/32 of its clinical applied dosage） has a dose- and time-dependent cytotoxicity to HCEP cells in vitro, with inducing cellapoptosis via a death receptor-mediated mitochondriondependent pathway.

A New Characterization Approach of Weld Nugget Growth by Real-Time Input Electrical Impedance

The in-process changes of weld nugget growth during the Resistance Spot Welding were investigated based on the resistance of input electrical impedance. To compute the time varying resistance of input electrical impedance, the welding voltage and current signals are measured simultaneously and then converted into complex-valued signals by using Hilbert transform. Comparing with the dynamic contact resistance as reported in literature, it showed that the time varying resistance of input electrical impedance can be accurately correlated with the physical changes of weld nugget growth. Therefore, it can be used to characterize the in-process changes of weld nugget growth. Several new findings were reported based on the investigation of spot welds under no weld, with and without weld expulsion conditions.

Genetic Diversity of Tea Plant(Camellia Sinensis(L.) O.Kuntze)in Wuling Mountainous Area Revealed by ISSR Marker

Genetic diversity and relationship of 183 tea germplasms were assessed by inter-simple sequence repeat(ISSR) marker.The study optimized the ISSR-PCR system for tea plants.Results show that genetic similarity among 183 tea ascensions was between 0.52-0.93,indicating a wide gene pool and a broad genetic variation of Wuling tea resources.The highest similarity of all materials between No1 and No2 was 0.93.Dendrogram of the183 tea germplasms were protracted by UPGMA clustering analysis also revealed the genetic diversity and relationship of the tea germplasms of Wuling mountainous area.Besides,fingerprint of the 183 tea germplasms were constructed.

Polyester-tethered near-infrared fluorophores confined in colloidal nanoparticles:Tunable and thermoresponsive aggregation and biomedical applications

Intricate assembly of multiple molecular chromophores assisted by protein scaffolds is essential in tuning the optical absorption and energy transfer in the light-harvesting complexes of the photosynthetic systems in nature.However,it remains a challenge to achieve such structural complexity and functionality in synthetic polymer-chromophore systems.Here,we report a series of polyester-tethered pyrrolopyrrole cyanine derivatives and their colloidal nanoparticles dispersed in water,which show tunable J-or H-aggregation excitonic coupling and near-infrared fluorescence by precise control of the polymer chain lengths,composition,and temperature.Moreover,the optimal fluorescence or photothermal effect of the Jaggregate nanoparticles enables broad applications in fluorescence or photoacoustic bioimaging and phototherapy.

二维黑磷基纳米材料在光催化中的应用

黑磷是继石墨烯之后又一种新型的单元素二维材料。具有独特的层状结构、超高的载流子迁移率和由层厚调控的禁带宽度,在光催化领域具有广阔的应用前景。然而,单一黑磷材料的禁带宽度较窄(≤1.5 eV),光生载流子极易复合,导致其光催化性能较低。另外,黑磷表面的磷原子易与环境中的氧气发生反应形成P_(x)O_(y),降低了黑磷材料的稳定性。因此,较低的催化性能和不稳定性极大地限制了黑磷材料的实际应用。针对上述问题,可以通过将黑磷材料与其他材料复合形成一系列的等离子体复合材料和多维异质结的方式,来提高光催化剂的活性和循环稳定性。本文综述了近年来二维黑磷纳米片与金属、半导体和碳材料等复合后形成的复合材料在光催化裂解水产氢、降解有机污染物、CO_(2)还原和固氮等方面的研究进展。最后,对未来二维黑磷基光催化材料的研究方向进行了分析和展望。

Environmentally responsive dual-targeting nanotheranostics for overcoming cancer multidrug resistance

The development of multiple drug resistance(MDR) to chemotherapy and subsequent treatment failures are major obstacles in cancer therapy. An attractive option for combating MDR is inhibiting the expression of P-glycoprotein(P-gp) in tumor cells. Here, we report a novel chemosensitizing agent, XMD8-92,which can down-regulate P-gp. To enhance the specificity of MDR chemotherapy, a promising nanotheranostic micelle system based on poly(ethylene glycol)-blocked-poly(L-leucine)(PEG-b-Leu) was developed to simultaneously carry the anticancer drug doxorubicin, chemosensitizing agent XMD8-92, and superparamagnetic iron oxide nanoparticles(SPIOs). Featured with MDR environmentally responsive dual-targeting capability, controllable drug delivery, and efficient magnetic resonance(MR) imaging characteristics, the prepared nanotheranostics(DXS@NPs) showed outstanding in vitro cytotoxicity on MDR cells(SCG 7901/VCR) with only 53% of cells surviving compared to 90% of DOX-treated cells.Furthermore, efficient tumor inhibition and highly reduced systemic toxicity were exhibited by MDR tumor-bearing mice treated with DXS@NPs. Overall, the environmentally responsive dual-targeting nanotheranostics represent a promising approach for overcoming cancer MDR.

Low-dimensional MXenes as noble metal-free co-catalyst for solar-to-fuel production:Progress and prospects

Direct conversion of solar energy into chemical fuels via semiconducting materials through photocatalytic technology is a sustainable way to tackle the global warming, environmental issue and energy crisis. Transition metal carbides and nitrides(MXenes), a newly emerging class of 2D layered materials, has gained tremendous attention as a noble metal-free co-catalyst for boosting photoreactivity due to its extraordinary characteristics like elemental abundance, excellent electrical conductivity, abundant surface functional groups, unique hydrophilic behavior and flexible modulation of chemical composition. The rational integration of low-dimensional MXenes in the form of 2D layered structures or 0D quantum dots with diverse semiconducting materials offer more versatile and robust heterostructured-photocatalysts that are applicable in solar fuel generation. Herein, we summarize the recent advances and achievements in the synthesis of low-dimensional MXenes and their application in hydrogen production from water splitting and CO_(2) photoreduction. A comprehensive discussion of the fundamentals for solar fuel production, synthesis strategies and theoretical calculations for MXenes-based photocatalysts are also given. Finally, the existing challenges and further perspectives of MXenes-based nanostructures for efficient solar fuel production are addressed.

Mineral iron based self-assembling: bridging the small molecular drugs and transformative application

The nanoparticle-based treatment and diagnosis of cancer remain challenging in clinical translation, mainly due to the hurdles that can be associated with the development of targeted delivery, biological side effects, poor drug loading efficiency (DLE), and instability and so on [1,2].

Maltohexaose-based probes for bacteria-specific imaging:Great sensitivity,specificity and translational potential

Infectious diseases have always been a major cause of mobility and mortality,early and accurate diagnosis is important for their management.However,current clinical diagnosis for bacterial infection still remains troublesome.Recently,many attempts on molecular imaging have been made for prompt bacteria detection,especially for early and precise disease diagnosis.Among them,maltohexaose-based probes serve as a superb candidate due to the bacteria-specific maltodextrin transport pathway.These probes can visualize bacterial foci with unparalleled sensitivity and specificity.Such metabolism-based targeting strategy offers a powerful delivery platform for imaging and theranostic agents,providing good translational potential for developing antibacterial agents.