Discovery of a urea-based hit compound as a novel inhibitor of transforming growth factor-ß type 1 receptor: in silico and in vitro studies.

Transforming growth factor ß type 1 receptor (TGFßR1), a crucial serine-threonine kinase, is central to the TGFß/Smad signaling pathway, governing cellular processes like growth, differentiation, apoptosis, and immune response. This pathway is closely linked to the epithelial-mesenchymal transition (EMT) process, which plays an important role in the metastasis of hepatocellular carcinoma (HCC). To date, only limited inhibitors targeting TGFßR1 have entered clinical trials, yet they encounter challenges, notably high toxicity, in clinical applications. Herein, an efficient virtual screening pipeline was developed. Eighty compounds were screened from a pool of over 17 million molecules based on docking scores and binding free energy. Four compounds were manually selected with the assistance of enhanced sampling method BPMD (binding pose metadynamics). The binding stability of these four compounds complexed with TGFßR1 was subsequently studied through long-timescale conventional molecular dynamics simulations. The three most promising compounds were subjected to in vitro bioactivity assays. Cpd272 demonstrated moderate inhibitory activity against TGFßR1, with an IC50 value of 1.57 ± 0.33 µM. Moreover, it exhibited cytotoxic effects on human hepatocellular carcinoma cell line Bel-7402. By shedding light on the binding mode of the receptor-ligand complexes, Cpd272 was identified as a hit compound featuring a novel urea-based scaffold capable of effectively inhibiting TGFßR1.

Low beauvericin concentrations promote PC-12 cell survival under oxidative stress by regulating lipid metabolism and PI3K/AKT/mTOR signaling.

Beauvericin (BEA), a naturally occurring cyclic peptide with good pharmacological activity, has been widely explored in anticancer research. Although BEA is toxic, studies have demonstrated its antioxidant activity. However, to date, the antioxidant mechanisms of BEA remain unclear. Herein, we conducted a comprehensive and detailed study of the antioxidant mechanism of BEA using an untargeted metabolomics approach, subsequently validating the results. BEA concentrations of 0.5 and 1 µM significantly inhibited H2O2-induced oxidative stress (OS), decreased reactive oxygen species levels in PC-12 cells, and restored the mitochondrial membrane potential. Untargeted metabolomics indicated that BEA was primarily involved in lipid-related metabolism, suggesting its role in resisting OS in PC-12 cells by participating in lipid metabolism. BEA combated OS damage by increasing phosphatidylcholine, phosphatidylethanolamine, and sphingolipid levels. In the current study, BEA upregulated proteins related to the PI3K/AKT/mTOR pathway, thereby promoting cell survival. These findings support the antioxidant activity of BEA at low concentrations, warranting further research into its pharmacological effects.

Identification, expression profiles, and binding properties of chemosensory protein 18 in Plutella xylostella (Lepidoptera: Plutellidae).

Chemosensory proteins (CSPs) are highly efficient carry tools to bind and deliver hydrophobic compounds, which play an important role in the chemosensory process in insects. The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is a cosmopolitan pest that attacks cruciferous crops. However, the detailed physiological functions of CSPs in P. xylostella remain limited to date. Here, we identified a typical CSP, named PxylCSP18, in P. xylostella and investigated its expression patterns and binding properties of volatiles. PxylCSP18 was highly expressed in antennae and head (without antennae), and the expression level in the male antennae of P. xylostella was obviously higher than that in the female antennae. Moreover, PxylCSP18 has a relatively broad binding spectrum. Fluorescence competitive binding assays showed that PxylCSP18 had strong binding abilities with 14 plant volatiles (Ki < 10 µM) that were repellent or attractive to P. xylostella. Notably, PxylCSP18 had no significant binding affinity to (Z)-11-hexadecenal, (Z)-11-hexadecenyl acetate, and (Z)-11-hexadecenyl alcolol, which are the pheromone components of P. xylostella. The attractive effects of trans-2-hexen-1-ol and isopropyl isothiocyanate to male adults and the attractive effects of isopropyl isothiocyanate and the repellent effects of linalool to female adults were significantly decreased after knocked down the expression of PxylCSP18. Our results revealed that PxylCSP18 might play an important role in host plant detection, avoidance of unsuitable hosts, and selection of oviposition sites; however, it does not participate in mating behavior. Overall, these results extended our knowledge on the CSP-related functions, which provided insightful information about CSP-targeted insecticides.

Incidence of Inflammatory Bowel Disease in Urban China: A Nationwide Population-based Study.

BACKGROUND & AIMS: Limited studies have evaluated the burden of inflammatory bowel disease (IBD) in China. We aimed to estimate the incidence of IBD including ulcerative colitis (UC) and Crohn's disease (CD) in urban China. METHODS: The national urban incidence in 2016 was calculated based on urban basic medical insurance from 2012 to 2016 in China by using a 4-year washout period. The incidence in Yinzhou District estimated from the Yinzhou electronic health care record database was used to test the accuracy of the results from insurance data. RESULTS: A total of 95,555 patients with IBD were identified. The incidence in 2016 was 10.04 (95% confidence interval, 6.95-13.71) per 100,000 person-years. The incidence rates of both UC and CD were higher among males than among females. There was a sharp increase in UC incidence before the age of 30 years and stabilization in later years (50-79 years old), whereas CD incidence peaked at 30 to 34 years old and experienced decline subsequently. The incidence of UC was much greater than that of CD, with a UC-to-CD incidence ratio of 12.61. The results from the Yinzhou database confirmed these results. CONCLUSIONS: This study is the first to draw a portrait of the distribution of IBD in urban China. The difference in IBD incidence between urban China and other countries suggests an association between the IBD burden and industrialization process. The accelerating urbanization and industrialization process in China, a country with a population of 1.4 billion people, will likely increase the burden of IBD.

Design, synthesis and biological evaluation of novel 3,4-dihydro-2H-[1,4]oxazino [2,3-f]quinazolin derivatives as EGFR-TKIs.

Starting with our previously reported work, a novel series of 3,4-dihydro-2H-[1,4]oxazino[2,3-f]quinazolin-derivatives were designed, synthesized and evaluated as potent EGFR tyrosine kinase inhibitors. All of the compounds showed significant inhibitory activities against EGFRwt kinase (IC50 ≤ 937.7 nM). Among them, compound 7j demonstrated the most potent inhibitory activity toward EGFRwt tyrosine kinase with IC50 value of 25.69 nM and showed good antiproliferative activities against NCI-H1563 and H1975 cells. The median cytotoxic concentration (CC50) showed that most of the tested compounds displayed almost no cytotoxicity in vitro against 16HBE cells. In view of the reported compounds activity, the structure deserves further optimization as cancer treatment agents.

Risk factors for epidural anesthesia blockade failure in cesarean section: a retrospective study.

BACKGROUND: Epidural anesthesia (EA) is the regional anesthesia technique preferred over spinal anesthesia for pregnant women requiring cesarean section and post-operative pain control. EA failure requires additional sedation or conversion to general anesthesia (GA). This may be hazardous during sedation or GA conversion because of potentially difficult airways. Therefore, this retrospective study aimed to determine the risk factors for epidural failure during cesarean section anesthesia. METHODS: We retrospectively analyzed parturients who underwent cesarean section under EA and catheterization at the Chang Gung Memorial Hospital in Taiwan between January 1 and December 31, 2018. Patient data were collected from the medical records. EA failure was defined as the administration of any intravenous anesthetic at any time during a cesarean section, converting it into GA. RESULTS: A total of 534 parturients who underwent cesarean section were recruited for this study. Of them, 94 (17.6%) experienced EA failure during cesarean section. Compared to the patients with successful EA, those with EA failure were younger (33.0 years vs. 34.7 years), had received EA previously (60.6% vs. 37%), were parous (72.3% vs. 55%), and had a shorter waiting time (14.9 min vs. 16.5 min) (p < 0.05). Younger age (OR 0.91, 95% CI 0.86-0.95), history of epidural analgesia (OR 2.61, 95% CI 1.38-4.94), and shorter waiting time (OR 0.91, 95% CI 0.87-0.97) were estimated to be significantly associated with a higher risk of epidural anesthesia failure. CONCLUSION: The retrospective study found that parturients of younger age, previous epidural catheterization history, and inadequate waiting time may have a higher risk of EA failure. Previous epidural catheterization increased the risk of EA failure by 2.6-fold compared to patient with no history of catheterization.

Recent Progress of Spectroscopic Probes for Peroxynitrite and Their Potential Medical Diagnostic Applications.

Peroxynitrite (ONOO-) is a crucial reactive oxygen species that plays a vital role in cellular signal transduction and homeostatic regulation. Determining and visualizing peroxynitrite accurately in biological systems is important for understanding its roles in physiological and pathological activity. Among the various detection methods, fluorescent probe-based spectroscopic detection offers real-time and minimally invasive detection, high sensitivity and selectivity, and easy structural and property modification. This review categorizes fluorescent probes by their fluorophore structures, highlighting their chemical structures, recognition mechanisms, and response behaviors in detail. We hope that this review could help trigger novel ideas for potential medical diagnostic applications of peroxynitrite-related molecular diseases.

Low-Cost, User-Friendly, All-Integrated Smartphone-Based Microplate Reader for Optical-Based Biological and Chemical Analyses.

The quantitative detection of different molecular targets is of utmost importance for a variety of human activities, ranging from healthcare to environmental studies. Bioanalytical methods have been developed to solve this and to achieve the quantification of multiple targets from small volume samples. Generally, they can be divided into two different classes: point of care (PoC) and laboratory-based approaches. The former is rapid, low-cost, and user-friendly; however, the majority of the tests are semiquantitative, lacking in specificity and sensitivity. On the contrary, laboratory-based approaches provide high sensitivity and specificity, but the bulkiness of experimental instruments and complicated protocols hamper their use in resource-limited settings. In response, here we propose a smartphone-based device able to support laboratory-based optical techniques directly at the point of care. Specifically, we designed and fabricated a portable microplate reader that supports colorimetric, fluorescence, luminescence, and turbidity analyses. To demonstrate the potential of the device, we characterized its analytical performance by detecting a variety of relevant molecular targets (ranging from antibodies, toxins, drugs, and classic fluorophore dyes) and we showed how the estimated results are comparable to those obtained from a commercial microplate reader. Thanks to its low cost (<$300), portability (27 cm [length] × 18 cm [width] × 7 cm [height]), commercially available components, and open-source-based system, we believe it represents a valid approach to bring high-precision laboratory-based analysis at the point of care.

Two-Dimensional Modeling of Nano Zero-Valent Iron Transport and Retention before and after Phosphate Adsorption.

The mobility of nano zero-valent iron (nZVI) will greatly affect its practical application as a remediation material for contaminated groundwater. One-dimensional (1D) column tests are commonly used in previous work to study its migration behavior, but the two-dimensional (2D) test is still very limited. This study reports a novel research system to study the 2D transport and retention behavior of colloids and solutes, which includes a 2D model test setup and the corresponding image analysis method. The transport behaviors of methyl orange (MO), nZVI, and phosphate-loaded nZVI (PnZVI) are studied using this system. The results show that the research system can reasonably describe the tempo-spatial concentration distribution of colloids and solutes. After phosphate adsorption, the mobility of nZVI is enhanced due to the increase in negative surface charge, which implies a potential environmental risk of nZVI to facilitate contaminant transport. The migration of PnZVI is not significantly influenced by its density, which is faster than MO in the longitudinal direction. The range of the plume of PnZVI in the longitudinal direction is larger than that of MO, which implies that PnZVI has a stronger longitudinal dispersion than MO.

Investigate the effect of honey on the absorption of seven active ingredients from wu-tou decoction in rats.

Wu-tou decoction has been used as a traditional Chinese medicine prescription for thousands of years. It comprises five herbs, namely Radix Aconiti Preparata, Ephedrae Herba, Astragali Radix, Glycyrrhiza Radix, and Paeoniae Radix Alba. In addition, the original prescription contains honey, but in modern research, the existence of honey is commonly ignored. The aim was to investigate the effect of absorption in rats after oral wu-tou decoction with or without honey. In this research, a rapid and sensitive UPLC-MS/MS method was investigated for the quantitative analysis of ephedrine, pseudoephedrine, paeoniflorin, calycosin-7-glucoside, glycyrrhizic acid, liquiritin, and benzoylmesaconine in rat plasma after single and continuous oral decoctions. The results of the pharmacokinetic parameters showed that Cmax , CL/F, AUC0-t , and AUC0-∞ in the honey group were significantly increased than those in the non-honey group except for ephedrine and pseudoephedrine. The same trend was observed regardless of single or continuous oral administrations. Research studies showed that honey could promote the absorption of some effective components in wu-tou decoction in rats, enhance bioavailability, and provide a theoretical basis for the scientific and rational compatibility of the original prescription.

Rice MutLγ, the MLH1-MLH3 heterodimer, participates in the formation of type I crossovers and regulation of embryo sac fertility.

The development of embryo sacs is crucial for seed production in plants, but the genetic basis regulating the meiotic crossover formation in the macrospore and microspore mother cells remains largely unclear. Here, we report the characterization of a spontaneous rice female sterile variation 1 mutant (fsv1) that showed severe embryo sacs abortion with low seed-setting rate. Through map-based cloning and functional analyses, we isolated the causal gene of fsv1, OsMLH3 encoding a MutL-homolog 3 protein, an ortholog of HvMLH3 in barley and AtMLH3 in Arabidopsis. OsMLH3 and OsMLH1 (MutL-homolog 1) interact to form a heterodimer (MutLγ) to promote crossover formation in the macrospore and microspore mother cells and development of functional megaspore during meiosis, defective OsMLH3 or OsMLH1 in fsv1 and CRISPR/Cas9-based knockout lines results in reduced type I crossover and bivalent frequency. The fsv1 and OsMLH3-knockout lines are valuable germplasms for development of female sterile restorer lines for mechanized seed production of hybrid rice.

Gly-tRF enhances LCSC-like properties and promotes HCC cells migration by targeting NDFIP2.

BACKGROUND: Accumulating evidence demonstrates that tRFs (tRNA-derived small RNA fragments) and tiRNAs (tRNA-derived stress-induced RNA), an emerging category of regulatory RNA molecules derived from transfer RNAs (tRNAs), are dysregulated in in various human cancer types and play crucial roles. However, their roles and mechanisms in hepatocellular carcinoma (HCC) and liver cancer stem cells (LCSCs) are still unknown. METHODS: The expression of glycine tRNA-derived fragment (Gly-tRF) was measured by qRT-PCR. Flow cytometric analysis and sphere formation assays were used to determine the properties of LCSCs. Transwell assays and scratch wound assays were performed to detect HCC cell migration. Western blotting was conducted to evaluate the abundance change of Epithelial-mesenchymal transition (EMT)-related proteins. Dual luciferase reporter assays and signalling pathway analysis were performed to explore the underlying mechanism of Gly-tRF functions. RESULTS: Gly-tRF was highly expressed in HCC cell lines and tumour tissues. Gly-tRF mimic increased the LCSC subpopulation proportion and LCSC-like cell properties. Gly-tRF mimic promoted HCC cell migration and EMT. Loss of Gly-tRF inhibited HCC cell migration and EMT. Mechanistically, Gly-tRF decreased the level of NDFIP2 mRNA by binding to the NDFIP2 mRNA 3' UTR. Importantly, overexpression of NDFIP2 weakened the promotive effects of Gly-tRF on LCSC-like cell sphere formation and HCC cell migration. Signalling pathway analysis showed that Gly-tRF increased the abundance of phosphorylated AKT. CONCLUSIONS: Gly-tRF enhances LCSC-like cell properties and promotes EMT by targeting NDFIP2 and activating the AKT signalling pathway. Gly-tRF plays tumor-promoting role in HCC and may lead to a potential therapeutic target for HCC.

Performance of a fully-automated system on a WHO malaria microscopy evaluation slide set.

BACKGROUND: Manual microscopy remains a widely-used tool for malaria diagnosis and clinical studies, but it has inconsistent quality in the field due to variability in training and field practices. Automated diagnostic systems based on machine learning hold promise to improve quality and reproducibility of field microscopy. The World Health Organization (WHO) has designed a 55-slide set (WHO 55) for their External Competence Assessment of Malaria Microscopists (ECAMM) programme, which can also serve as a valuable benchmark for automated systems. The performance of a fully-automated malaria diagnostic system, EasyScan GO, on a WHO 55 slide set was evaluated. METHODS: The WHO 55 slide set is designed to evaluate microscopist competence in three areas of malaria diagnosis using Giemsa-stained blood films, focused on crucial field needs: malaria parasite detection, malaria parasite species identification (ID), and malaria parasite quantitation. The EasyScan GO is a fully-automated system that combines scanning of Giemsa-stained blood films with assessment algorithms to deliver malaria diagnoses. This system was tested on a WHO 55 slide set. RESULTS: The EasyScan GO achieved 94.3 % detection accuracy, 82.9 % species ID accuracy, and 50 % quantitation accuracy, corresponding to WHO microscopy competence Levels 1, 2, and 1, respectively. This is, to our knowledge, the best performance of a fully-automated system on a WHO 55 set. CONCLUSIONS: EasyScan GO's expert ratings in detection and quantitation on the WHO 55 slide set point towards its potential value in drug efficacy use-cases, as well as in some case management situations with less stringent species ID needs. Improved runtime may enable use in general case management settings.

Design, synthesis and biological evaluation of 2,3-dihydro-[1,4]dioxino[2,3-f]quinazoline derivatives as EGFR inhibitors.

Epidermal growth factor receptor (EGFR) is the most attractive target for drug research in non-small cell lung cancer (NSCLC). The first-generation EGFR tyrosine kinase inhibitors (TKIs) Gefetinib and Elotinib showed good clinical efficacy on lung adenocarcinoma tumors, but almost all patients developed resistance to these inhibitors over time. Quinazoline and quinoline derivatives are common targeted inhibitors of EGFR kinase, and their structural optimization is an important direction for the development of effective targeted anticancer drugs. Based on these facts, a series of heterocyclic 2,3-dihydro-[1,4]dioxino[2,3-f]quinazoline derivatives have been designed and synthesized and their structures were confirmed by spectral analyses. The cytotoxic activity of the newly synthesized compounds was evaluated against the human kidney epithelial T293 cell line, normal lung cell lines WI-38, non-small cell lung cancer A549 and NCI-H157 cell lines using MTT. The tested compounds showed an evident anticancer activity against the tested cell lines, especially compound 13c, which was the most potent anticancer agent with half maximal inhibitory concentrations (IC50) between 8.82 and 10.24 µM. Docking study showed that compound 13b could be nicely bound to the ATP binding pocket of EGFR. In addition, the inhibitory activity of the target compounds against epidermal growth factor receptor tyrosine kinase (EGFR-TK) was evaluated. Results indicated the ability of the target compounds to inhibit EGFR-TK with half maximal inhibitory concentrations (IC50) in the range of 10.29 nM to 652.3 nM. In view of the reported compound activity, the structure deserves further optimization as cancer treatment agents.

An Orthogonal Tyrosyl-tRNA Synthetase/tRNA Pair from a Thermophilic Bacterium for an Expanded Eukaryotic Genetic Code.

The Escherichia coli-derived tyrosyl-tRNA synthetase was the first enzyme engineered for genetic code expansion in a eukaryotic system but can charge only a limited set of structurally simple noncanonical amino acids. In contrast, the thermophilic Methanocaldococcus jannaschii-derived tyrosyl-tRNA synthetase mutants, used in only a prokaryotic system, can charge a surprisingly large set of structurally diverse ncAAs, due to their remarkable structural ability to tolerate mutations. Inspired by this, we characterized a new class of tyrosyl-tRNA synthetase/tRNATyr pairs from thermophilic bacterium Geobacillus stearothermophilus, which is homologous to the E. coli tyrosyl-tRNA synthetase but with better thermostability. This new pair is both orthogonal in mammalian cells and in Saccharomyces cerevisiae for genetic code expansion and can charge a diverse set of ncAAs with a comparable cellular efficiency, better specificity, and lower background, as compared to those of its E. coli homologue. This thermostable enzyme provides an alternative scaffold for synthetase library screening or evolution to genetically encode more structurally complex ncAAs in eukaryotic cells.

Structure-based identification of novel CK2 inhibitors with a linear 2-propenone scaffold as anti-cancer agents.

Protein kinase CK2 has emerged as an attractive cancer therapeutic target. Previous studies have highlighted the challenge of optimizing CK2 ATP-competitive inhibitors that have low druggability due to their polycyclic ring scaffolds. Therefore the development of novel inhibitors with non-polycyclic scaffolds emerges as a promising strategy for drug discovery targeting CK2. In this current study, based on the similar predicted binding poses of the linear 2-propenone scaffold of isoliquiritigenin with that of the polycyclic inhibitor CX-4945, a series of 2-propenone derivatives containing an amine-substituted five-membered heterocycle and a benzoic acid were designed, synthesized and evaluated for their in vitro CK2 inhibition and anti-cancer activity. Compound 8b was found to be the most potent CK2 inhibitor (IC50 = 0.6 µM) with the anti-proliferative activity on HepG2 cancer cells (IC50 = 14 µM), compared to the activity of isoliquiritigenin (IC50 = 17 µM and 51 µM, respectively). Molecular docking was performed to understand the binding modes of the newly designed 2-propenone derivatives with CK2. Compound 8b formed the most favorable network of hydrogen bonds with both the hinge region and positive area. Our results indicate that CK2 derivatives with a linear 2-propenone scaffold are promising candidates for anti-cancer drug discovery.

Synthesis and anti-tumor activity of [1,4] dioxino [2,3-f] quinazoline derivatives as dual inhibitors of c-Met and VEGFR-2.

Both c-Met and VEGFR-2 were important targets for cancer therapies. In order to develop reversible and non-covalent c-Met and VEGFR-2 dual inhibitors, a series of [1,4]dioxino[2,3-f]quinazoline derivatives were designed and synthesized. The enzyme assay demonstrated that most target compounds had inhibition potency on both c-Met and VEGFR-2 with IC50 values in nanomolar range especially compounds 7m and 7k. Based on further cell proliferation assay in vitro, compound 7k showed significantly anti-tumor activity in vivo on a hepatocellular carcinoma (MHCC97H cells) xenograft mouse model. We docked the compound 7m with c-Met and VEGFR-2 kinases, and interpreted the SAR of these analogues. All results indicated that the target compounds were dual inhibitors of c-Met and VEGFR-2 kinases that held promising potential in cancer therapy.

Chemotaxis-Instructed Intracellular Staphylococcus aureus Infection Detection by a Targeting and Self-Assembly Signal-Enhanced Photoacoustic Probe.

Intracellular invasion and the survival of Staphylococcus aureus in phagocytic cells has been regarded as one of the mechanisms that leads to the treatment failure of S. aureus infection and potential antibiotic resistance. The detection of infected phagocytic cells plays an important role in guiding antibiotic treatment and in reducing drug resistance. The development of a sensitive and specific imaging probe to visualize the intracellular bacteria is quite challenging. In this work, we report a photoacoustic agent (MPC) that is able to detect intracellular S. aureus infection through a dynamic process, including (i) active targeting and internalization into macrophage cells, (ii) specific molecular tailoring by caspase-1 in infected macrophage cells, and (iii) enhancement of the photoacoustic (PA) signal owing to molecular self-assembly. The PA signal per area of the "stimuli-induced assembly" agent (MPC) increases more than 2-fold over that of the active targeting control agent (MPSC). Finally, based on this approach, the average PA signal in the infected site is enhanced by approximately 2.6-fold over that of the control site. We envision that this PA contrast agent may provide a new approach for the selective and sensitive diagnosis of an intracellular bacterial infection.

Proteomic Identification of Protein Tyrosine Phosphatase and Substrate Interactions in Living Mammalian Cells by Genetic Encoding of Irreversible Enzyme Inhibitors.

Protein tyrosine phosphatases (PTPs) play critical roles in cell signaling pathways, but identification of unknown PTPs for a given substrate in live cells remain technically challenging. Here, we synthesized a series of tyrosine-based irreversible PTP inhibitors and characterized by site-specific encoding on substrate proteins in cells with an expanded genetic code. By fine-tuning the chemical reactivity, we identified optimal active amino acid probes to covalently cross-link a PTP and its substrate both in vitro and in mammalian cells. Using HER2 as an example, we provide first direct evidence of HER2 Y1023 and SHP2 cross-linking in situ in living human cells. Moreover, proteomic analysis using our approach identified PTP1B as a novel phosphatase for HER2 that specifically dephosphorylated pY1221 position, which may shed light on the puzzle of PTP1B's role in HER2 positive breast cancer. This novel method provides a useful tool for dissecting tyrosine phosphoregulation in living cells.

Ultrasensitive Tyrosinase-Activated Turn-On Near-Infrared Fluorescent Probe with a Rationally Designed Urea Bond for Selective Imaging and Photodamage to Melanoma Cells.

Melanoma is a highly aggressive malignancy and early monitoring and diagnosis are challenging at present. Tyrosinase is overexpressed in melanoma and regarded as an important biological marker for diagnosis and treatment. Thus, the selective and sensitive detection of tyrosinase is of great significance. To date, a few fluorescent probes have been reported for the detection of tyrosinase in vitro or in vivo. However, a highly sensitive near-infrared probe for tyrosinase monitoring is still missing. In this study, the Gibbs free energy change of different urea bonds during spontaneous hydrolysis is analyzed with the aid of chemical thermodynamic computation. On the basis of this analysis, we modified the dye methylene blue with a rationally designed urea bond to specifically create a probe, called MB1, for rapid detection of tyrosinase. Our experimental results demonstrated that MB1 can serve as a highly sensitive near-infrared responsive fluorescent probe for the monitoring and bioimaging of tyrosinase. In addition, the activated MB1 probe can effectively kill melanoma cells by photodynamic therapy. Thus, the near-infrared probe has great potential for monitoring and treating melanoma.