Predictive value of PD-L1 and TMB for short-term efficacy prognosis in non-small cell lung cancer and construction of prediction models.

Objective: To investigate the correlation between programmed death ligand 1(PD-L1), tumor mutation burden (TMB) and the short-term efficacy and clinical characteristics of anti-PD-1 immune checkpoint inhibitor combination chemotherapy in NSCLC patients. The efficacy of the prediction model was evaluated. Methods: A total of 220 NSCLC patients receiving first-line treatment with anti-PD-1 immune checkpoint inhibitor combined with chemotherapy were retrospectively collected. The primary endpoint was short-term efficacy ORR. The correlation between short-term efficacy, PD-L1, TMB, and clinical characteristics using χ2 test or t-test was evaluated. Screen the independent prognostic factors using univariate and multivariate logistic regression analyses, and construct a nomogram prediction model using the "rms" package in R software. Using receiver operating characteristic (ROC) curve analysis to evaluate the independent Prognostic factors and the prediction model. Using decision curve analysis (DCA) to verify the superiority of the prediction model. Results: The mean values of PD-L1, TMB, neutrophils, lymphocytes, neutrophil-to-lymphocyte ratio, and albumin were the highest in the ORR group, PD-L1 expression and TMB correlated with epidermal growth factor receptor expression. Multivariate analyses showed that PD-L1, TMB, and neutrophil were independent prognostic factors for ORR. The area under the ROC curve (AUC) values of the ROC constructed based on these three indicators were 0.7104, 0.7139, and 0.7131, respectively. The AUC value under the ROC of the nomogram model was 0.813. The DCA of the model showed that all three indicators used together to build the prediction model of the net return were higher than those of the single indicator prediction model. Conclusion: PD-L1, TMB, and neutrophils are independent prognostic factors for short-term efficacy. The nomogram prediction model constructed using these three indicators can further improve predictive efficacy of ICIs in patients with NSCLC.

Meta-analytic and MaxEnt model prediction, the distribution of the Bactrocera minax (Diptera: Tephritidae), in China under changing climate.

The Tephritidae family causes damage to fruits in tropical and subtropical regions around the world, with Bactrocera minax Enderlein (Diptera: Tephritidae) widely distributed in China, causing severe economic damage to Chinese citrus. Currently, preventing the rapid spread of B. minax remains an effective strategy to control it as the climate continues to warm in the future. In this context, it is crucial to understand the potential geographic range of B. minax under climate change. We used meta-analysis to assess the survival of Tephritidae insects under temperature stress. We also used the maximum entropy (MaxEnt) model to predict the suitable regions and migration trajectories of B. minax in China under current and future climatic conditions. Through comprehensive analysis of the experimental data, we found that the survival rate of Tephritidae insects in the suitable temperature range showed an increasing trend with the increase in warming extent. Using the MaxEnt model, we observed that the highly suitable area, as well as the moderately suitable area of B. minax, were expanding in all 3 future climate scenarios, with the distribution moving toward the high latitude region and the coastal region of China. Our results also indicate that temperature and precipitation contribute more to the model in the current year. Combining multiexperiment data, our study demonstrates that the potential distribution of B. minax in China will expand under future climate warming scenarios, and these predictions will provide important information for monitoring B. minax and informing managers in developing control strategies.

Longitudinal Associations Between Interpersonal Distrust and Social Aggression During College: Disentangling the Within-Person Process from Stable Between-Person Differences.

There is a dearth of information on the relationship between interpersonal distrust and social aggression in the youth, although both may lead to negative interpersonal relationships. Furthermore, scholars have not explored whether interpersonal distrust influences later social aggression over time at the within-person level. This study used five wave longitudinal data to investigate the longitudinal association between interpersonal distrust and social aggression and the role of hostile attribution bias in this relationship; notably, it used a relatively rigorous approach-the random intercept cross-lagged panel model-to disentangle within-person processes from stable between-person differences. The final number of participants included 1053 undergraduate students (677 female students and 376 male students), and 64.3% were female students, with a mean age of 18.45 years (SD = 0.95) at first measurement. Participants completed assessments for interpersonal distrust, hostile attribution bias, and social aggression at five time points across 6-month intervals. At the within-person level, the results revealed that interpersonal distrust was a predictor of later social aggression and that hostile attribution bias acted as a longitudinal mediator in this relationship. This result indicates that to enhance interpersonal harmony and reduce individual hostility and aggression toward others, intervention programs should aim to reduce interpersonal distrust.

Can Treating Oneself Kindly Inspire Trust? The Role of Interpersonal Responsibility.

Self-compassion, as a personal psychological resource, has been proved to play an important role in coping with suffering. Based on self-determination theory, the present study attempts to establish that self-compassion can promote trust, and the sense of interpersonal responsibility mediates this relationship. Study 1 used cross-sectional data in a community sample of 322 adults to reveal that self-compassion was positively related to trust, and the mediating effects of the sense of interpersonal responsibility were significant. Study 2 used the latent cross-lagged panel model among 1304 college students at three-time points set at six-month intervals to replicate the results and proved the longitudinal mediating effects across groups. Finally, a casual chain design was used to test the mediation effect in Studies 3 and 4. The results indicated that self-compassion induced by writing task resulted in a sense of responsibility in Study 3 (N = 145), and the manipulated sense of responsibility promoted both trust behaviors and beliefs in Study 4 (N = 125). Through four studies, this study highlights a novel but unexpected viewpoint that treating oneself in a self-compassionate way can not only help individuals cope with various challenges but also motivate them to obtain interpersonal benefits. These findings can help motivate community workers and mental health researchers to increase social capital by focusing on self-compassion and interpersonal responsibility.

Polymer composite microspheres loading 177Lu radionuclide for interventional radioembolization therapy and real-time SPECT imaging of hepatic cancer.

BACKGROUND: Transarterial radioembolization (TARE) with 90Y-labeled glass and resin microspheres is one of the primary treatment strategies for advanced-stage primary and metastatic hepatocellular carcinoma (HCC). However, difficulties of real-time monitoring post administration and embolic hypoxia influence treatment prognosis. In this study, we developed a new biodegradable polymer microsphere that can simultaneously load 177Lu and MgO nanoparticle, and evaluated the TARE therapeutic efficacy and biosafety of 177Lu-PDA-CS-MgO microspheres for HCC treatment. METHODS: Chitosan microspheres were synthesized through emulsification crosslink reaction and then conducted surface modification with polydopamine (PDA). The 177Lu and nano MgO were conjugated to microspheres using active chemical groups of PDA. The characteristics of radionuclide loading efficiency, biodegradability, blood compatibility, and anti-tumor effectwere evaluated both in vitro and in vivo. SPECT/CT imaging was performed to monitor bio-distribution and bio-stability of 177Lu-PDA-CS-MgO after TARE treatment. The survival duration of each rat was monitored. HE analysis, TUNEL analysis, immunohistochemical analysis, and western blot analysis were conducted to explore the anti-tumor effect and mechanism of composited microspheres. Body weight, liver function, blood routine examination were monitored at different time points to evaluate the bio-safety of microspheres. RESULTS: The composite 177Lu-PDA-CS-MgO microsphere indicated satisfactory degradability, biocompatibility, radionuclide loading efficiency and radiochemical stability in vitro. Cellular evaluation showed that 177Lu-PDA-CS-MgO had significant anti-tumor effect and blocked tumor cell cycles in S phase. Surgical TARE treatment with 177Lu-PDA-CS-MgO significantly prolonged the medial survival time from 49 d to 105 d, and effectively inhibited primary tumor growth and small metastases spreading. Moreover, these microspheres indicated ideal in vivo stability and allowed real-time SPECT/CT monitoring for up to 8 weeks. Immunostaining and immunoblotting results also confirmed that 177Lu-PDA-CS-MgO had potential in suppressing tumor invasion and angiogenesis, and improved embolic hypoxia in HCC tissues. Further evaluations of body weight, blood test, and pathological analysis indicated good biosafety of 177Lu-PDA-CS-MgO microspheres in vivo. CONCLUSION: Our study demonstrated that 177Lu-PDA-CS-MgO microsphere hold great potential as interventional brachytherapy candidate for HCC therapy. Polymer composite microspheres loading 177Lu radionuclide and MgO nanoparticles for interventional radioembolization therapy and real-time SPECT imaging of hepatic cancer.

Research progress of hyperthermia in tumor therapy by influencing metabolic reprogramming of tumor cells.

Cellular metabolic reprogramming is an important feature of malignant tumors. Metabolic reprogramming causes changes in the levels or types of specific metabolites inside and outside the cell, which affects tumorigenesis and progression by influencing gene expression, the cellular state, and the tumor microenvironment. During tumorigenesis, a series of changes in the glucose metabolism, fatty acid metabolism, amino acid metabolism, and cholesterol metabolism of tumor cells occur, which are involved in the process of cellular carcinogenesis and constitute part of the underlying mechanisms of tumor formation. Hyperthermia, as one of the main therapeutic tools for malignant tumors, has obvious effects on tumor cell metabolism. In this paper, we will combine the latest research progress in the field of cellular metabolic reprogramming and focus on the current experimental research and clinical treatment of hyperthermia in cellular metabolic reprogramming to discuss the feasibility of cellular metabolic reprogramming-related mechanisms guiding hyperthermia in malignant tumor treatment, so as to provide more ideas for hyperthermia to treat malignant tumors through the direction of cellular metabolic reprogramming.

Accelerating effects of growing-season warming on tree seasonal activities are progressively disappearing.

The phenological changes induced by climate warming have profound effects on water, energy, and carbon cycling in forest ecosystems. In addition to pre-season warming, growing-season warming may drive tree phenology by altering photosynthetic carbon uptake. It has been reported that the effect of pre-season warming on tree phenology is decreasing. However, temporal change in the effect of growing-season warming on tree phenology is not yet clear. Combining long-term ground observations and remote-sensing data, here we show that spring and autumn phenology were advanced by growing-season warming, while the accelerating effects of growing-season warming on tree phenology were progressively disappearing, manifesting as phenological events converted from being advanced to being delayed, in the temperate deciduous broadleaved forests across the Northern Hemisphere between 1983 and 2014. We further observed that the effect of growing-season warming on photosynthetic productivity showed a synchronized decline over the same period. The responses of phenology and photosynthetic productivity had a strong linear relationship with each other, and both showed significant negative correlations with the elevated temperature and vapor pressure deficit during the growing season. These findings indicate that warming-induced water stress may drive the observed decline in the responses of tree phenology to growing-season warming by decelerating photosynthetic productivity. Our results not only demonstrate a close link between photosynthetic carbon uptake and tree seasonal activities but also provide a physiological perspective of the nonlinear phenological responses to climate warming.

Labeling of graphene oxide with [131I]AgI and its stability analysis.

To explore the new iodine labeling method of nanomaterials, graphene oxide (GO) was labeled by 131I with AgI nanoparticles. As a control, GO was also labeled by 131I with chloramine-T method. The stability of the two 131I labeling materials, viz. [131I]AgI-GO and [131I]I-GO was evaluated. The results show that [131I]AgI-GO is very stable in inorganic environment such as PBS and saline. However, it is not stable enough in serum. The instability of [131I]AgI-GO in serum can be attributed to the higher affinity of Ag to S of thiol group in cysteine than iodine ions and much more chance of interaction between thiol group and [131I]AgI nanoparticles on two-dimensional GO than in three-dimensional nanomaterials.

The effect of problematic smartphone use on school engagement and disengagement among middle school students: The mediating role of academic procrastination and sleep quality.

INTRODUCTION: Although a few research have tried to explore the relationship between problematic smartphone use (PSU) and school engagement, most of them are limited to relatively simple correlation, and the mechanism needs to be further explored. This research focused on the relationship between PSU and school engagement/disengagement, and intended to verify two mediation paths. METHODS: We conducted two studies in 2019 at a middle school in China. 289 students (44.6% girls), aged 11-18 (Mage = 13.25, standard deviation [SD] = 1.73), participated in Study 1, a longitudinal cross-lag analysis intend to verify the relationship between PSU and school engagement/disengagement. Using a separate sample, Study 2 explored the mediating roles of academic procrastination and sleep quality. Four hundred thirty-two students aged 11-19 (42.1% girls, Mage = 16.11, SD = 1.56) participated in this cross-sectional study. In both studies, all participants completed self-report measures in classrooms during regular school hours. RESULTS: In Study 1, the results showed that PSU (T1) could significantly predict school engagement/disengagement (T2), but school engagement/disengagement (T1) could not predict PSU (T2). In Study 2, we found that academic procrastination could mediate the effect of PSU on school engagement, and sleep quality could mediate the effect of PSU on both school engagement and disengagement. CONCLUSIONS: Results highlighted that the school engagement/disengagement of adolescents can be influenced by PSU through several different ways, through which we can protect adolescents from the negative effects of PSU.

The Effect of Cooling Layer Thickness and Coolant Velocity on Crystal Thermodynamic Properties in a Laser Amplifier.

Laser diode pumped solid-state lasers (DPSSLs) have been widely used in many fields, and their thermal effects have attracted more and more attention. The laser diode (LD) side-pumped amplifier, as a key component of DPSSLs, is necessary for effective heat dissipation. In this paper, instead of the common thermal analysis based only on a crystal rod model, a fluid-structure interaction model including a glass tube, cooling channel, coolant and crystal rod is established in numerical simulation using ANSYS FLUENT for the configuration of an LD array side-pumped laser amplifier. The relationships between cooling layer thickness, coolant velocity and maximum temperature, maximum equivalent stress, inlet pressure and the convective heat transfer coefficient are analyzed. The results show that the maximum temperature (or maximum equivalent stress) decreases with the increase in the coolant velocity; at low velocity, a larger cooling layer thickness with more coolant is not conductive enough for improved heat dissipation of the crystal rod; at high velocity, when the cooling layer thickness is above or below 1.5 mm, the influence of the cooling layer thickness on the maximum temperature can be ignored; and the effect of the cooling layer thickness on the maximum equivalent stress at high velocity is not very significant. The comprehensive influence of various factors should be fully considered in the design process, and this study provides an important reference for the design and optimization of a laser amplifier and DPSSL system.

Insights into the spontaneous multi-scale supramolecular assembly in an ionic liquid-based extraction system.

Herein, we report a four-step mechanism for the spontaneous multi-scale supramolecular assembly (MSSA) process in a two-phase system concerning an ionic liquid (IL). The complex ions, elementary building blocks (EBBs), [EBB]n clusters and macroscopic assembly (MA) sphere are formed step by step. The porous large-sized [EBB]n clusters in the glassy state can hardly stay in the IL phase and they transfer to the IL-water interface due to both electroneutrality and amphiphilicity. Then, the clusters undergo random collision in the interface driven by the Marangoni effect and capillary force thereafter. Finally, a single MA sphere can be formed owing to supramolecular interactions. To our knowledge, this is the first example realizing spontaneous whole-process supramolecular assembly covering microscopic, mesoscopic and macroscopic scales in extraction systems. The concept of multi-scale selectivity (MSS) is therefore suggested and its mechanism is revealed. The selective separation and solidification of metal ions can be realized in a MSSA-based extraction system depending on MSS. In addition, insights into the physicochemical characteristics of ILs from microscopic, mesoscopic to macroscopic scales are provided, and especially, the solvation effect of ILs on the large-sized clusters leading to the phase-splitting is examined. It is quite important that the polarization of uranyl in its complex, the growing of uranyl clusters in an IL as well as the glassy material of uranyl are investigated systematically on the basis of both experiment and theoretical calculations in this work.

Comparison and Mechanism Study of Antibacterial Activity of Cationic and Neutral Oligo-Thiophene-Ethynylene.

Photodynamic therapy (PDT) is a potential approach to resolve antibiotic resistance, and phenylene/thiophene-ethynylene oligomers have been widely studied as effective antibacterial reagents. Oligomers with thiophene moieties usually exhibit good antibacterial activity under light irradiation and dark conditions. In the previous study, we verified that neutral oligo-p-phenylene-ethynylenes (OPEs) exhibit better antibacterial activity than the corresponding cationic ones; however, whether this regular pattern also operates in other kinds of oligomers such as oligo-thiophene-ethynylene (OTE) is unknown. Also, the antibacterial activity comparison of OTEs bearing cyclic and acyclic amino groups will offer useful information to further understand the role of amino groups in the antibacterial process and guide the antibacterial reagent design as amino groups affect the antibacterial activity a lot. We synthesized four OTEs bearing neutral or cationic, cyclic, or acyclic amino groups and studied their antibacterial activity in detail. The experimental results indicated that the OTEs exhibited better antibacterial activity than the OPEs, the neutral OTEs exhibited better antibacterial activity in most cases, and OTEs bearing cyclic amino groups exhibited better antibacterial activity than those bearing acyclic ones in most cases. This study provides useful guidelines for further antibacterial reagent design and investigations.

Temperature-robust and ratiometric G-quadruplex proximate DNAzyme assay for robustly monitoring of uranium pollution and its microbial biosorbents screening.

Uranium pollution in environment and food chain is a serious threat to public security and human health. Herein, we proposed a temperature-robust, ratiometric, and label-free bioassay based on G-quadruplex proximate DNAzyme (G4DNAzyme), accommodating us to precisely monitor uranium pollution and biosorption. The proximity of split G-quadruplex probes was proposed to sense UO22+-activated DNAzyme activity, thus eliminating the use of chemically labeled nucleic acid probes. And the simultaneous monitoring of G-quadruplex and double-stranded structures of DNAzyme probes contributed to a ratiometric and robust detection of UO22+. Particularly, the separation of enzymatic digestion and fluorescence monitoring endued a robust and highly responsive detection of UO22+ upon the temperature of enzymatic digestion process ranged from 18° to 41 °C. Consequently, G4DNAzyme assay allowed a robust, label-free and ratiometric quantification of uranium. We demonstrated the feasibility of G4DNAzyme assay for estimating uranium pollution in water and aquatic product samples. Ultimately, G4DNAzyme assay was adopted to serve as the platform to screen bacterial species and conditions for uranium biosorption, promising its roles in uranium associated biosafety control.

Multimodality labeling of NGR-functionalized hyaluronan for tumor targeting and radiotherapy.

Hyaluronan (HA) is a negatively charged linear polysaccharide that can interact with cluster determinant 44 (CD44) overexpressed cancers. However, HA can also bind to excess substrates in the human body leading to the lower specificity of tumor targeting. Conjugation of other targeting group to HA could enhance the uptake by cancer cell comparing to that of native HA. In this study, we develop the multi-functionalized HA (177Lu-DOTA/Alexa647-HA100-N) for malignant tumor targeting. An asparagine-glycine-arginine (NGR) based peptide was selected for HA functionalization. The peptide is known to target CD13 receptor that is overexpressed in malignant tumors with abundant blood vessels, such as lung cancer. Furthermore, the fluorescent probe Alexa Fluor 647 for ex vivo/in vivo tracking and the radionuclide 177Lu for radioactive therapy were both labeled on the material. The functionalized HA could be bound by lung cancer cells and breast cancer cells. In vivo fluorescent imaging showed that the material could accumulate in the tumor site for more than 96 h. The 177Lu labeling of functionalized HA was stable for more 48 h at physiological conditions. The accumulation of 177Lu-DOTA/Alexa647-HA100-N in the tumor of lung cancer (NCI-H292) bearing mice was 1.91±0.97%ID/g, and it was about 17 times higher than the value in blood. Conclusion: The multimodality labeled functional HA was successfully prepared and could be fluorescent trackable ex vivo and in vivo. It showed high potential to be used for malignant cancer radiotherapy for its specific targeting property to tumors and radiotoxicity from the labeled 177Lu radionuclide.

Complexation of Cyclic Glutarimidedioxime with Cerium: Surrogating for Redox Behavior of Plutonium.

The complexation of cerium with glutarimidedioxime (H2L) was studied by potentiometry, ESI-mass spectrometry, and cyclic voltammetry. Crystallization of [CeIV(HL)3]+ from Ce3+ starting reactant indicated spontaneous complexation-driven oxidation. In aqueous solution, Ce3+ ions form three successive complexes, Ce(HL)2+, Ce(HL)2+, and Ce(HL)3 (where HL- stands for the singly deprotonated ligand). The interactions of glutarimidedioxime with metal ions are dominantly electrostatic in nature, and the stability constants of the complexes are correlated to the charge density of metal ions. Extrapolations of predicted stability constant (log ß) values were made from plotting effective charge and the ionic radius of the metal ion for Pu3+ and Pu4+. The stability constants of PuIV(HL)3+ and PuIII(HL)2+ are estimated to be 27.74 and 19.75, respectively. The differences of stability constants mean that glutarimidedioxime selectively binds Pu4+ over Pu3+ by a factor of about 8 orders of magnitude, suggesting Pu4+ would be stabilized by chelation with glutarimidedioxime. The mechanism of reduction of Pu4+ to Pu3+ in acidic solution is explained by decomposition of glutarimidedioxime through acid hydrolysis rather than a chelation-driven mechanism.

Investigating Antibacterial Efficiency and Mechanism of Oligo-thiophenes under White Light and Specific Biocidal Activity against E. coli in Dark.

More strategies are required to develop better photosensitizers for photodynamic therapy (PDT). As oligo(phenylene-ethynylene) electrolytes (OPE), oligo(thiophene)s with primary amine as pendant groups (P-OT), and oligo(thiophene ethynylene) (OTE) exhibit excellent light-induced biocidal activity, we desire to converge the molecular design principles of these three kinds of antibacterial agents to combine their advantages to obtain high efficiency and economic biocides. Thus, four oligo(thiophene)s (OTs) were designed and synthesized in this study. The light-induced and dark antibacterial efficacy of the four OTs against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) were both evaluated. Notably, all the OTs present high biocidal efficacy in the broad spectrum at low (micromolar) concentrations after white-light irradiation. In particular, the low cell cytotoxicity of OTs exhibits their good biocompatibility. These results illustrate that the OTs could work as promising PDT biocides. Interestingly, OT-3 shows a strong and specific dark killing activity against E. coli. The higher biocidal efficacy of T-OTs compared with that of Q-OTs confirms the tertiary amine is a better pendant group for π-conjugated antibacterial agents against E. coli. Mechanistic investigation proves ROS is the necessary element for antibiosis under white light. The interacting efficacy of the OT to the cell membrane, involving synergistic effects between hydrophilic-hydrophobic interactions and electrostatic attractions, is also critical in the killing process. The membrane intercalating activity plays a more essential role, as indicated by the antibacterial activity of OTs. The results provide a unique insight into the relationship between molecular structure and antibacterial activities of this class of antibacterial agents.

Dual-radiolabelling of an injectable hyaluronan-tyramine-bisphosphonate hybrid gel for in vitro and in vivo tracking.

Hyaluronan (HA) have been widely used as the ideal biomaterials. It is important to understand their degradation and distribution for better optimization. From a new aspect of using radiotracers, we designed the HA-tyramine-bisphosphonate derivative for dual-labelling with two radionuclides (99mTc and 131I) simultaneously for in vitro and in vivo tracking. This dual-radiolabelled HA derivative can still be non-covalently crosslinked by hydroxyapatites to form injectable gel. The excellent properties of the gel, such as robust, biodegradable, and self-healing capacity were maintained. We firstly proved the possibility to distinguish different radionuclides in the degraded gel using the high-resolution gamma-ray spectrometry. The radiolabelled gel showed lower toxicity than pure hydroxyapatites against various cell lines, while the in vivo results proved that the 99mTc/131I-labelling of the gel was safe and stable enough for imaging and quantitatively tracking. The present method can also be applied for the development of dual-radiolabelled gels from other polysaccharides.

Biocidal Activity and Mechanism Study of Unsymmetrical Oligo-Phenylene-Ethynylenes.

Bacterial contamination and the spread of antibiotic-resistant bacteria demand alternate methods to deal with bacterial infections. With particular advantages, photodynamic therapy (PDT) is a promising approach. As a kind of photosensitizer for PDT, light-induced antibacterial compounds like oligo-p-phenylene-ethynylenes (OPEs) have been widely investigated while these studies mainly focus on OPEs with quaternary ammonium salts. In our previous study, OPEs with tertiary amino groups (T-OPEs) were reported to exhibit a better antibacterial activity than the corresponding quaternary ammonium salts, which make it important to develop T-OPEs and further investigate their structure-activity relationship. Additionally, the terminal structure of the reported OPEs mainly consists of quaternary ammonium salts or tertiary amino groups, which could not be linked to other materials. Thus, to develop more effective and multifunctional antibacterial agents, we designed and synthesized four unsymmetrical OPEs having terminal amino groups, which could be linked to other functional units by covalent bonds. Their antibacterial activity against Gram-positive and Gram-negative bacteria and the mechanism have been investigated. The OPEs showed effective biocidal activity under fiber light irradiation, and no dark killing was observed. The mechanism study indicates that OPEs could penetrate and perturb the cell membrane and generate ROS under light irradiation, both of which could influence their antibacterial activity. The penetrating ability of OPEs is partly dependent on their lipophilicity and the structure and composition of the cell membrane.

Evaluating the Photodynamic Biocidal Activity and Investigating the Mechanism of Thiazolium Cyanine Dyes.

In order to develop ideal photosensitizers for photodynamic therapy (PDT), a thiazolium group was introduced in cyanine dyes to possess the advantages of intense absorption in the visible region and anti-microbial activity. We evaluated the anti-bacterial activity of the three thiazolium cyanine dyes against Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria) in vitro. This is the first time that such kinds of cyanine dyes are applied in the photodynamic antibiotic area. Cyanines display excellent anti-bacterial activity to S. aureus and E. coli exposed to white light irradiation, and the corresponding light-induced biocidal efficacy of cyanines increased with irradiation time and concentration. At the same time, there was no observation of dark anti-bacterial abilities. Especially, cyanines show low cell cytotoxicity and excellent biocompatibility. These results suggest that thiazolium cyanine could work as a photosensitizer in PDT with great promise and broad applications for killing bacteria. Mechanistic studies suggest that the reactive oxygen species (ROS) is the vital factor for combating bacteria exposure to white light conditions, whereas it is not the only determining factor of the biocidal activity. The interaction of the cyanine to the cell membrane also plays a critical role in killing bacteria, which has exhibited a synergic effect of electrostatic and hydrophobic interactions. It influences the cell uptake and the membrane perturbation activity of the cyanines, which indirectly affects the biocidal activity.