Polymer-enhanced peroxidase activity of ceria nanozyme for highly sensitive detection of alkaline phosphatase.

Nanoceria have demonstrated a wide array of catalytic activity similar to natural enzymes, holding considerable significance in the colorimetric detection of alkaline phosphatase (ALP), which is a biomarker of various biological disorders. However, the issues of physiological stability and formation of protein corona, which are strongly related to their surface chemistry, limit their practical application. In this work, CeO2 nanoparticles characterized by enhanced dimensional uniformity and specific surface area were synthesized, followed by encapsulation with various polymers to further increase catalytic activity and physiological stability. Notably, the CeO2 nanoparticles encapsulated within each polymer exhibited improved catalytic characteristics, with PAA-capped CeO2 exhibiting the highest performance. We further demonstrated that the PAA-CeO2 obtained with enhanced catalytic activity was attributed to an increase in surface negative charge. PAA-CeO2 enabled the quantitative assessment of AA activity within a wide concentration range of 10 to 60 µM, with a detection limit of 0.111 µM. Similarly, it allowed for the evaluation of alkaline phosphatase activity throughout a broad range of 10 to 80 U/L, with a detection limit of 0.12 U/L. These detection limits provided adequate sensitivity for the practical detection of ALP in human serum.

Phase II study of novel orally PI3Kα/δ inhibitor TQ-B3525 in relapsed and/or refractory follicular lymphoma.

This registration study assessed clinical outcomes of TQ-B3525, the dual phosphatidylinositol-3-kinase (PI3K) α/δ inhibitor, in relapsed and/or refractory follicular lymphoma (R/R FL). This phase II study (ClinicalTrials.gov NCT04324879. Registered March 27, 2020) comprised run-in stage and stage 2. R/R FL patients after ≥2 lines therapies received oral 20 mg TQ-B3525 once daily in a 28-day cycle until intolerable toxicity or disease progression. Primary endpoint was independent review committee (IRC)-assessed objective response rate (ORR). Based on results (ORR, 88.0%; duration of response [DOR], 11.8 months; progression-free survival [PFS], 12.0 months) in 25 patients at run-in stage, second stage study was initiated and included 82 patients for efficacy/safety analysis. Patients received prior-line (median, 3) therapies, with 56.1% refractory to previous last therapies; 73.2% experienced POD24 at baseline. At stage 2, ORR was 86.6% (71/82; 95% CI, 77.3-93.1%), with 28 (34.2%) complete responses. Disease control rate was 95.1% due to 7 (8.5%) stable diseases. Median time to response was 1.8 months. Among 71 responders, median DOR was not reached; 18-month DOR rate was 51.6%. with median follow-up of 13.3 months, median PFS was 18.5 (95% CI, 10.2-not estimable) months. Median overall survival (OS) was not reached by cutoff date; 24-month OS rate was estimated as 86.1%. Response rates and survival data were consistent across all subgroups. Grade 3 or higher treatment-related adverse events were observed in 63 (76.8%) cases, with neutropenia (22.0%), hyperglycemia (19.5%), and diarrhea (13.4%) being common. TQ-B3525 showed favorable efficacy and safety for R/R FL patients after ≥2 lines prior therapies.

Synthesis and structure-activity relationship of novel thiazole aminoguanidines against MRSA and Escherichia coli.

Novel lead thiazole aminoguanidines exhibited strong activity against Gram-positive bacteria. The potential targets of these substances are undecaprenyl diphosphate synthase (UPPS) and undecaprenyl diphosphate phosphatase (UPPP). Here, we report the synthesis and antibacterial evaluation of a library of thiazole aminoguanidines analogues, wherein the rotatable bond is inserted between the C2 position of thiazole and hydrophobic group. The molecular flexibility is increased, and new analogues with strong activity against MRSA and E. coli are produced. The best compound 4i showed rapid sterilization and low tendency to induce bacterial resistance. The IC50 of compound 4i to EcUPPS enzyme is 145 µmol L-1 (58 µg mL-1). Compound 4i can also inhibit and destroy bacterial biofilms. These thiazole aminoguanidines can be developed as potential therapeutic candidates in the future.

Resistance to preservatives and the viable but non-culturable state formation of Asaia lannensis in flavored syrups.

Food security is a crucial issue that has caused extensive concern, and the use of food flavors has become prevalent over time. we used the molecular biological techniques, preservative susceptibility testing, viable but non-culturable (VBNC) state induction testing, and a transcriptome analysis to examine the bacterial contamination of favored syrup and identify the causes and develop effective control measures. The results showed that Asaia lannensis WLS1-1 is a microorganism that can spoil food and is a member of the acetic acid bacteria families. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests showed that WLS1-1 was susceptible to potassium sorbate (PS), sodium benzoate (SB), and sodium sulffte (SS) at pH 4.0. It revealed a progressive increase in resistance to these preservatives at increasing pH values. WLS1-1 was resistant to PS, SB and SS with an MIC of 4.0, 2.0 and 0.5 g/L at pH 5.0, respectively. The MIC values exceed the maximum permissible concentrations that can be added. The induction test of the VBNC state demonstrated that WLS1-1 lost its ability to grow after 321 days of PS induction, 229 days of SB induction and 52 days of SS induction combined with low temperature at 4°C. Additionally, laser confocal microscopy and a propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR) assay showed that WLS1-1 was still alive after VBNC formation. There were 7.192 ± 0.081 (PS), 5.416 ± 0.149 (SB) and 2.837 ± 0.134 (SS) log10(CFU/mL) of viable bacteria. An analysis of the transcriptome data suggests that Asaia lannensis can enter the VBNC state by regulating oxidative stress and decreasing protein synthesis and metabolic activity in response to low temperature and preservatives. The relative resistance of Asaia lannensis to preservatives and the induction of the VBNC state by preservatives are the primary factors that contribute to the contamination of favored syrup by this bacterium. To our knowledge, this study represents the first evidence of the ability of Asaia lannensis to enter the VBNC state and provides a theoretical foundation for the control of organisms with similar types of activity.

Enhanced osteogenic and bactericidal performance of premixed calcium phosphate cement with photocrosslinked alginate thin film.

The increasing prevalence of implant-associated infections (IAI) in orthopedics remains a public health challenge. Calcium phosphates (CaPs) are critical biomaterials in dental treatments and bone regeneration. It is highly desirable to endow CaPs with antibacterial properties. To achieve this purpose, we developed a photocrosslinked methacrylated alginate co-calcium phosphate cement (PMA-co-PCPC) with antibacterial properties, using α-tricalcium phosphate (α-TCP) powders with 16% amorphous contents as solid phase, liquid phases containing CuCl2 and SrCl2 as an inhibitor, and CaCl2 as an activator to construct PCPC. When CaCl2 started to activate the hydration reaction, Sr2+ or Cu2+ ions were exchanged with Ca2+, and α-TCP dissolution was restarted and gradually hydrated to form calcium-deficient hydroxyapatite (CDHA). PMA was added to crosslink with Cu/Sr ions and form gel-layer-wrapped hydrated CDHA. This study explored the binding mechanism of PMA and PCPC and the ion release rule of Ca2+ → Sr2+/Cu2+, optimized the construction of several antibacterial PMA-co-PCPC materials, and analyzed the physical, chemical, and biological properties. Because of the combined effect of Cu and Sr ions, the scaffold exhibited a potential antibacterial activity, promoting bone formation and vascular regeneration. This work provides a basis for designing antibacterial calcium phosphate biomaterials with controllable treatment, which is an important characteristic for preventing IAI of biomaterials.

Rapid detection of mexX in Pseudomonas aeruginosa based on CRISPR-Cas13a coupled with recombinase polymerase amplification.

The principal pathogen responsible for chronic urinary tract infections, immunocompromised hosts, and cystic fibrosis patients is Pseudomonas aeruginosa, which is difficult to eradicate. Due to the extensive use of antibiotics, multidrug-resistant P. aeruginosa has evolved, complicating clinical therapy. Therefore, a rapid and efficient approach for detecting P. aeruginosa strains and their resistance genes is necessary for early clinical diagnosis and appropriate treatment. This study combines recombinase polymerase amplification (RPA) and clustered regularly interspaced short palindromic repeats-association protein 13a (CRISPR-Cas13a) to establish a one-tube and two-step reaction systems for detecting the mexX gene in P. aeruginosa. The test times for one-tube and two-step RPA-Cas13a methods were 5 and 40 min (including a 30 min RPA amplification reaction), respectively. Both methods outperform Quantitative Real-time Polymerase Chain Reactions (qRT-PCR) and traditional PCR. The limit of detection (LoD) of P. aeruginosa genome in one-tube and two-step RPA-Cas13a is 10 aM and 1 aM, respectively. Meanwhile, the designed primers have a high specificity for P. aeruginosa mexX gene. These two methods were also verified with actual samples isolated from industrial settings and demonstrated great accuracy. Furthermore, the results of the two-step RPA-Cas13a assay could also be visualized using a commercial lateral flow dipstick with a LoD of 10 fM, which is a useful adjunt to the gold-standard qRT-PCR assay in field detection. Taken together, the procedure developed in this study using RPA and CRISPR-Cas13a provides a simple and fast way for detecting resistance genes.

Selecting Suitable Near-Native Lignins for Research.

There are several methods to isolate near-native lignins, including milled-wood lignin, enzymatic lignin, cellulolytic enzyme lignin, and enzymatic mild-acidolysis lignin. Which one is the most representative of the native lignin? Herein, near-native lignins were isolated from different plant groups and structurally analyzed to determine how well these lignins represented their native lignin counterparts. Analytical methods were applied to understand the molecular weight, monomer composition, and distribution of interunit linkages in the structure of the lignins. The results indicated that either enzymatic lignin or cellulolytic enzyme lignin may be used to represent native lignin in softwoods and hardwoods. None of the lignins, however, appeared to represent native lignins in grasses (monocot plants) because of substantial syringyl/guaiacyl differences. Complicating the understanding of grass lignin structure, large amounts of hydroxycinnamates acylate their polysaccharides and, when released, are often conflated with actual lignin monomers.

Antimicrobial Peptide-Inspired Design of Amino-Modified Lignin with Improved Antimicrobial Activities.

A major challenge to make use of lignin as an antimicrobial material is the weak antimicrobial activity of industrial lignin. Inspired by the antimicrobial mechanism of actions of antimicrobial peptides, alkyldiamines were employed as lysine mimics for lignin modifications. Accordingly, aminoalkyl-modified lignins with different degrees of substitution of amino groups and different hydrophobicity were synthesized. The chemical structure, properties, and antimicrobial activities of the as-prepared aminoalkyl lignins were thoroughly characterized with state-of-the-art technologies. The results indicated that aminobutyl lignin showed enhanced antimicrobial activity against S. aureus and E. coli and performed even better than copper ions. The antimicrobial mechanism of action of the as-prepared aminobutyl lignin was similar to that of polylysine, which damaged the cell membrane, leading to the leakage of intracellular molecules and death of the cell. This study provides a feasible approach to afford modified lignin with enhanced antimicrobial performance, which would facilitate the high-value valorization of lignin as biological materials.

Fundicoccus culcitae sp. nov., a novel potential bacteriocin producing bacterium isolated from a spoiled eye mask.

A Gram-positive, facultatively anaerobic, oval beaded-shape, oxidase-negative, and non-motile bacterium designated DM20194951T was isolated from a spoiled eye mask obtained from Guangdong, China. Based on the 16S rRNA gene sequence, phylogenetic analysis indicated that strain DM20194951T showed the highest sequence similarity (95.8%) to Fundicoccus ignavus WS4937T. Meanwhile, strain DM20194951T could be distinguished from the type strains in the genus Fundicoccus by distinct phenotypic and genotypic traits. Strain DM20194951T grew variably with 1-2% (w/v) NaCl and tolerated pH 6.0-10.0. Growth was observed from 28 to 37 °C. The diagnostic diamino acids in the cell-wall peptidoglycan consisted of aspartic and glutamic acids as well as alanine. The predominant fatty acids were C18:1 ω9c, C16:0, and C16:1 ω9c. In the polar lipid profile, two glycolipids, three phospholipids, one phosphatidylglycerol, and one diphosphatidylglycerol were found. No respiratory quinones were detected. The DM20194951T genome is 3.2 Mb in size and contains a G + C content of 38.1%. A gene cluster for lactococcin 972 family bacteriocin production was found in the DM20194951T genome. Based on morphological, genotypic, and phylogenetic data, strain DM20194951T should be considered to represent a novel species in the genus Fundicoccus, for which the name Fundicoccus culcitae sp. nov. is proposed with the type strain DM20194951T (= KCTC 43472T = GDMCC 1.3614T).

Nutrient condition modulates the antibiotic tolerance of Pseudomonas aeruginosa.

The variation in nutrient content across diverse environments has a significant impact on the survival and metabolism of microorganisms. In this study, we examined the influence of nutrients on the antibiotic tolerance of the PAO1 strain of Pseudomonas aeruginosa. Our findings indicate that under nutrient-rich conditions, this strain exhibited relatively high tolerance to ceftazidime, chloramphenicol, and tetracycline, but not aminoglycosides and fluoroquinolones. Transcriptome analysis revealed that genes associated with antibiotic tolerance were expressed more efficiently in nutrient-rich media, including ribosomal protein genes and multidrug efflux pump genes, which conferred higher tetracycline tolerance to the strain. Furthermore, the genes responsible for translation, biosynthesis, and oxidative phosphorylation were suppressed when nutrients were limited, resulting in decreased metabolic activity and lower sensitivity to ciprofloxacin. Artificial interference with ATP synthesis utilizing arsenate confirmed that the curtailment of energy provision bolstered the observed tolerance to ciprofloxacin. In general, our results indicate that this strain of P. aeruginosa tends to activate its intrinsic resistance mechanisms in nutrient-rich environments, thereby enhancing resistance to certain antibiotics. Conversely, in nutrient-limited environments, the strain is more likely to enter a dormant state, which enables it to tolerate antibiotics to which it would otherwise be sensitive. These findings further suggest that antibiotics released in environments with varying eutrophication levels may have divergent effects on the development of bacterial antibiotic resistance.

Tannic Acid Interfacial Modification of Prochloraz Ethyl Cellulose Nanoparticles for Enhancing the Antimicrobial Effect and Biosafety of Fungicides.

With the poorly soluble and intrinsically unstable feature, prochloraz (Pro) was confronted with lower bioavailability in the crop defense against fungal erosion. Therefore, it was a challenging project to explore the innovative antifungal compound delivery system for improving bioavailability. The superior adhesive fungicide formulation was supposed to be an efficient pathway to enhance transmembrane permeability and biological activity. According to abundant phenolic hydroxyl groups, tannic acid (TA) was an ideal modified adhesive biomaterial to improve interfacial interactions. The fundamental purpose of this research was focused on the synergistic mechanism of TA-interfacial-modified Pro-ethyl cellulose (EC) nanoparticles for improving bioavailability and biosafety. In the stability test, TA-modified Pro-EC nanoparticles had the capacity to reduce Pro initial release burst, extending a persistent validity and improving anti-photodegradation property. The toxicity index of Pro-EC and Pro-EC-TA was approximately 2.93-fold and 4.96-fold that of Pro technical against Fusarium graminearum (F. graminearum), respectively. Compared with nonmodified EC nanoparticles, TA-modified EC nanoparticles obtained eminent transmembrane permeability and superior adherence ability to F. graminearum, for hydroxyl and carboxyl groups of TA to enhance interaction with target cell membranes. The contents of cellular reactive oxygen species induced by Pro-EC and Pro-EC-TA nanoparticles were about 2.31 times and 3.00 times that of the control check (CK), respectively. Compared to the CK group, the membrane potential and ergosterol values of F. graminearum treated with Pro-EC-TA nanoparticles were drastically reduced by 74.91 and 56.20%, respectively. In the biosafety assay, the maximum half-lethal concentration value of the TA-modified Pro-EC nanoparticles indicated that the acute toxicity of the Pro-EC-TA nanoparticles to adult zebrafish was approximately 8.34-fold reduced compared to that of the Pro technical. These findings demonstrated that the successful interfacial modification of Pro-EC nanoparticles with TA was a highly efficient, environmentally safe, and promising alternative for sustainable agricultural application, thus making the fungicide formulation process more simplified, easier fabrication, and lower cost.

[Clinical Characteristics and Prognostic Factors of Patients with Primary Parotid Gland Lymphoma].

OBJECTIVE: To explore the clinical characteristics and prognostic factors of patients with primary parotid gland lymphoma, and construct a prognostic model nomogram for patients with primary diffuse large B-cell lymphoma (DLBCL) of parotid gland. METHODS: Primary parotid gland lymphoma and primary DLBCL of parotid gland patients from 1984 to 2016 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate Cox regression analysis were conducted to determine the independent prognostic factors of primary parotid gland lymphoma and primary DLBCL of parotid gland, respectively. According to the established independent prognostic factors of primary DLBCL of parotid gland, nomogram was built to predict 3- and 5-year survival, and the discrimination and calibration of the model were evaluated by concordance index (C-index) and calibration plots. RESULTS: A total of 2 610 patients with primary parotid gland lymphoma were identified. Their median age was 66(15-99) years old, the male to female ratio was 1∶1.8, and 20.5% of them was primary DLBCL of parotid gland, which was the most common histological subtype in aggressive lymphomas. Multivariate Cox regression analysis showed that sex, age, Ann Arbor stage, years of diagnosis, marital status, histological subtype, surgery, and radiation were the independent prognostic factors of primary parotid gland lymphoma, while age, marital status, surgery, and chemotherapy were the independent prognostic factors of primary DLBCL of parotid gland. The C-index of the prediction model was 0.702(95%CI: 0.696-0.768), reflecting a good discrimination ability. The predicted value probability of the calibration plots was close to the actual value probability, reflecting a good accuracy ability. CONCLUSIONS: Sex, age, Ann Arbor stage, years of diagnosis, marital status, histological subtype, surgery, and radiation were the independent prognostic factors of primary parotid gland lymphoma. The nomogram survival prediction model for primary DLBCL of parotid gland patients can assist clinical decision effectively.

Outer Membrane Porins Contribute to Antimicrobial Resistance in Gram-Negative Bacteria.

Gram-negative bacteria depend on their cell membranes for survival and environmental adaptation. They contain two membranes, one of which is the outer membrane (OM), which is home to several different outer membrane proteins (Omps). One class of important Omps is porins, which mediate the inflow of nutrients and several antimicrobial drugs. The microorganism's sensitivity to antibiotics, which are predominantly targeted at internal sites, is greatly influenced by the permeability characteristics of porins. In this review, the properties and interactions of five common porins, OmpA, OmpC, OmpF, OmpW, and OmpX, in connection to porin-mediated permeability are outlined. Meanwhile, this review also highlighted the discovered regulatory characteristics and identified molecular mechanisms in antibiotic penetration through porins. Taken together, uncovering porins' functional properties will pave the way to investigate effective agents or approaches that use porins as targets to get rid of resistant gram-negative bacteria.

Ruxolitinib improves hematopoietic regeneration by restoring mesenchymal stromal cell function in acute graft-versus-host disease.

Acute graft-versus-host disease (aGVHD) is a severe complication of allogeneic hematopoietic stem cell transplantation. Hematopoietic dysfunction accompanied by severe aGVHD, which may be caused by niche impairment, is a long-standing clinical problem. However, how the bone marrow (BM) niche is damaged in aGVHD hosts is poorly defined. To comprehensively address this question, we used a haplo-MHC-matched transplantation aGVHD murine model and performed single-cell RNA-Seq of nonhematopoietic BM cells. Transcriptional analysis showed that BM mesenchymal stromal cells (BMSCs) were severely affected, with a reduction in cell ratio, abnormal metabolism, compromised differentiation potential, and defective hematopoiesis-supportive function, all of which were validated by functional assays. We found that ruxolitinib, a selective JAK1/2 inhibitor, ameliorated aGVHD-related hematopoietic dysfunction through a direct effect on recipient BMSCs, resulting in improved proliferation ability, adipogenesis/osteogenesis potential, mitochondria metabolism capacity, and crosstalk with donor-derived hematopoietic stem/progenitor cells. By inhibiting the JAK2/STAT1 pathway, ruxolitinib maintained long-term improvement of aGVHD BMSC function. Additionally, ruxolitinib pretreatment in vitro primed BMSCs to better support donor-derived hematopoiesis in vivo. These observations in the murine model were validated in patient samples. Overall, our findings suggest that ruxolitinib can directly restore BMSC function via the JAK2/STAT1 pathway and, in turn, improve the hematopoietic dysfunction caused by aGVHD.

Clinical significance of plasma PD-L1+ exosomes in the management of diffuse large B cell lymphoma.

PD-L1+ exosome have been reported to be a promising prognostic biomarker in various cancers. However, its clinical value in diffuse large B cell lymphoma (DLBCL) has not been defined yet. In this study, a total of 165 plasma samples from 78 patients with DLBCL undergoing standard first-line R-CHOP regimens were collected at three different time points (pretreatment, and after 3 and 6 cycles of R-CHOP) to determine the proportions of PD-L1+ exosomes by flow cytometry. We found that high pretreatment plasma PD-L1+ exosome correlated with indicators of poor clinical outcome that included high Ki-67 expression (P = 0.02), double expressor lymphoma (P = 0.005), immunohistochemical PD-L1+ tumor tissue (P = 0.006), and the baseline maximal standardized uptake values (P = 0.0003). Pretreatment plasma PD-L1+ exosome was an independent factor by multivariate analysis with logistic regression (P = 0.0301). Moreover, the pretreatment PD-L1+ exosome was a strong predictor of final treatment responses of either CR or non-CR by ROC analysis (P < 0.001). PD-L1+ exosome level declined significantly in patients who experienced CR (pretreatment vs. after 3 cycles/after 6 cycles, P < 0.05), but not in the non-CR group. Intriguingly, plasma PD-L1+ exosome after 3 cycles (AUC = 0.857; 95%CI: 0.728-0.939) might represent a more sensitive indicator than radiographic assessment after 3 cycles (AUC = 0.626; 95%CI: 0.477-0.758) for evaluating the therapeutic response of DLBCL patients (P = 0.0136). Our results suggest that plasma PD-L1+ exosomes may represent a new biomarker for the dynamic monitoring of treatment response.

Geraniol attenuates virulence factors by inhibiting quorum sensing of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen that can cause severe respiratory tract infections. Geraniol, a chemical component of essential oils, has antimicrobial and anti-inflammatory activities, along with low toxicity. However, the effect and mechanism of geraniol against P. aeruginosa virulence factors are rarely studied. In this study, we investigated the quorum sensing (QS) inhibitory effects and mechanisms of geraniol against P. aeruginosa PAO1, using physiological and biochemical techniques, quantitative reverse transcription polymerase chain reaction, and transcriptomics. Geraniol slightly affected P. aeruginosa PAO1 growth, prolonged the lag phase, and delayed growth periods in a concentration-dependent manner. Geraniol inhibited three QS systems of P. aeruginosa, las, rhl, and pqs by suppressing the expression level of their key genes, including the three signal synthetase encoding genes of lasI, rhlI, and pqsABCDEH, and the corresponding signal receptor encoding genes of lasR, rhlR, and pqsR. Geraniol also suppressed certain virulence genes regulated by these three QS systems, including rhlABC, lasAB, lecAB, phzABMS, and pelABG, resulting in the attenuation of the related virulence factors, rhamnolipids, exoprotease LasA, elastase, lectin, pyocyanin, and biofilm. In conclusion, geraniol can suppress the virulence factors of P. aeruginosa PAO1 by inhibiting the three QS systems of las, rhl, and pqs. This study is significant for improving the treatment of bacterial infections caused by P. aeruginosa.

Removal of antibiotic resistant bacteria in wastewater by aggregation-induced emission photosensitizer.

The spread of antibiotic resistant bacteria from wastewater to the environment will pose serious threats to human health. It is a potential solution to prepare photosensitizers with broad-spectrum antibacterial activity for use in the photo-oxidation process to supplement the wastewater treatment system. Here, an aggregation-induced emission photosensitizer with D-π-A structure (TBTPy) has been reasonably designed and successfully developed. TBTPy can generate singlet oxygen with extraordinarily high efficiency under white-light irradiation owing to the small singlet-triplet energy gap. TBTPy has a rapid and efficient photo-oxidative killing effect on bacteria and fungi (such as MRSA, S. aureus, E. coli and C. albicans). TBTPy kills bacteria by binding to bacterial surface and releasing singlet oxygen to destroy cell membrane, leading to leakage of bacterial genetic material. This successful case can provide practical guidance for the subsequent development of AIE photosensitizers.

N,N-dimethyl chitosan oligosaccharide (DMCOS) promotes antifungal activity by causing mitochondrial damage.

By modifying chitosan oligosaccharide (COS) with the Eschweiler-Clarke reaction, the chitosan oligosaccharide derivative DMCOS was synthesized. FT-IR, 1D and 2D NMR spectra, MALDI-ToF MS, and elemental analysis were applied to analyze the structure of DMCOS, which revealed that the primary amines were converted into tertiary amines after methylation. DMCOS displayed less thermal stability than COS. In comparison to COS, it was discovered that DMCOS possessed more potent antimicrobial activity against four bacterial strains (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) and three yeast strains (Candida albicans, Candida tropicalis, and Candida parapsilosis). The antioxidant studies indicated that DMCOS had less antioxidant activity than COS. Consequently, ROS level elevated in C. albicans cells following treatment with DMCOS, which decreased mitochondrial membrane potential. It was recalled that DMCOS may kill C. albicans by causing mitochondrial damage. In addition, DMCOS was demonstrated to be non-cytotoxic.

High value valorization of lignin as environmental benign antimicrobial.

Lignin is a natural aromatic polymer of p-hydroxyphenylpropanoids with various biological activities. Noticeably, plants have made use of lignin as biocides to defend themselves from pathogen microbial invasions. Thus, the use of isolated lignin as environmentally benign antimicrobial is believed to be a promising high value approach for lignin valorization. On the other hand, as green and sustainable product of plant photosynthesis, lignin should be beneficial to reduce the carbon footprint of antimicrobial industry. There have been many reports that make use of lignin to prepare antimicrobials for different applications. However, lignin is highly heterogeneous polymers different in their monomers, linkages, molecular weight, and functional groups. The structure and property relationship, and the mechanism of action of lignin as antimicrobial remains ambiguous. To show light on these issues, we reviewed the publications on lignin chemistry, antimicrobial activity of lignin models and isolated lignin and associated mechanism of actions, approaches in synthesis of lignin with improved antimicrobial activity, and the applications of lignin as antimicrobial in different fields. Hopefully, this review will help and inspire researchers in the preparation of lignin antimicrobial for their applications.

Photosensitizers with aggregation-induced far-red/near-infrared emission for versatile visualization and broad-spectrum photodynamic killing of pathogenic microbes.

The exploration of photosensitizers with aggregation-induced emission (AIE PSs) for efficient visualization and broad-spectrum photodynamic killing of pathogenic microbes is a significant task. Herein, two far-red/near-infrared AIE-active PSs (TBTPy and TBTCy) were attained to show efficient Type I and Type II ROS generation, benefiting from the efficient ISC processes. The attained AIE PSs, especially TBTPy with bright emission, showed advantages in discriminating G+ bacteria over G- bacteria, and distinguishing dead E. coli from lived one. Both TBTPy and TBTCy have the capacity of broad-spectrum photodynamic killing of pathogenic microbes in vitro with considerable safety for mammalian cells. Antimicrobial mechanism is found to be changing osmotic pressure of cytoplasm in E. coli, causing cell deformation and destruction of S. aureus and C. albicans. In vivo anti-infection experiment demonstrated AIE PSs can accelerate the healing process of the burned wounds on rats infected by methicillin-resistant S. aureus (MRSA) or E. coli, indicating their potential to treat tertiary burns in clinical application. Therefore, the attained AIE PSs hold great promise as antimicrobial candidates in infective therapeutic application.