A novel 2-aminophenalenone-based fluorescent probe designed for monitoring H2O2 for in vitro and in vivo bioimaging

A significant compound in living organisms, hydrogen peroxide (H2O2) plays a dual role as a signalling molecule in cellular communication and as a pivotal biomarker in assessing disease and oxidative stress. Thus, the detection of abnormal changes in H2O2 levels is essential to understanding its function and involvement in biological systems. The growing demand to meet the specific needs for applications, particularly in biological systems, has sharpened focus on highly sensitive, highly selective molecular sensors and, in turn, heightened interest in these diagnostic tools with innovative designs. In our study, 2-aminophenalenone (2-AP) was used for the first time as a fluorophore in a fluorescent probe. The 2-APB molecule obtained from the reaction of 2-AP with 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) benzyl chloroformate exhibited a highly selective and sensitive (i.e. 62 nM) detection profile for H2O2 compared with the other reactive oxygen species, anions, and metal cations. Moreover, offering naked-eye detection in aqueous solutions, 2-APB demonstrated excellent sensing performance, detection and real-time monitoring in relation to exogenous H2O2 in cells and endogenous H2O2 in zebrafish embryos.

Surgical Trends in Breast Cancer in Turkey: An Increase in Breast-Conserving Surgery

PURPOSE

Breast cancer is the most frequent cancer in women, and there is a great variability in surgical practice for treating that cancer in different countries. The aims of this study were to analyze the effect of guidelines from the Turkish Federation of Breast Diseases Societies on academic institutions that have breast centers and to evaluate surgical practice in Turkey in 2018.

PATIENTS AND METHODS

Between January and March 2019, a survey was sent to breast surgeons who were working in breast centers in academic institutions. The sampling frame included 24 academic institutions with breast centers in 18 cities in Turkey to evaluate interdisciplinary differences among breast centers and seven regions in Turkey regarding patients’ choices, surgical approaches, and academic institutions.

RESULTS

All surgeons responded to the survey, and all 4,381 patients were included. Most of the surgeons (73.9%) were working in a breast center. Multidisciplinary tumor boards were performed in 87% of the breast centers. The average time between clinical evaluation and initiation of treatment was 29 days; the longest time was in Southeast Anatolia (66 days). Only 6% of patients had ductal carcinoma in situ. Sentinel lymph node biopsy was available in every region across the country and was performed in 64.5% of the patients. In 2018, the overall breast-conserving surgery rate was 57.3% in Turkey, and it varied from 72.2% in the Black Sea region to 33.5% in Central Anatolia (P < .001). Oncoplastic breast surgery options were available at all breast centers. However, 25% of the breast centers from the Black Sea region and half the breast centers from Eastern Anatolia and the Mediterranean region did not perform this type of surgery.

CONCLUSION

Increasing rates of nonpalpable breast cancer and decreasing rates of locoregional recurrences favored breast-conserving surgery, especially in developed countries. Guidelines from the Turkish Federation of Breast Diseases Societies resulted in more comprehensive breast centers and improved breast health in Turkey.

BODIPY-vinyl dibromides as triplet sensitisers for photodynamic therapy and triplet-triplet annihilation upconversion

We devised a new generation of halogen-based triplet sensitisers comprising geminal dibromides at the vinyl backbone of a BODIPY fluorophore. Incorporating geminal dibromides into the π-conjugation of BODIPY enhanced intersystem crossing due to the heavy atom effect, which in turn improved the extent of excited triplet states.

The effect of multifocal and multicentric tumours on local recurrence and survival outcomes in breast cancer

PURPOSE

The purpose of this study was to compare the multifocal (MF)/multicentric (MC) breast cancers with unifocal (UF) breast cancers in terms of tumour characteristics, treatment methods, loco-regional recurrence and survival rates.

METHODS

Patients who were treated with a diagnosis of early-stage breast cancer (stage I,II) and had regular follow-up were included in the study. MF tumours were defined as having more than one tumour focus in the same quadrant, whereas MC tumours refered to the presence of more than one tumour focus in different quadrants.

RESULTS

In total, 1865 patients with invasive breast cancer were evaluated, 1493 (80.1%) of whom had UF cancer, 330 (17.7%) had MF cancer, and 42 (2.3%) had MC cancer. After comparing the groups with each other, it was seen that MF and MC breast cancers occurred more often at early ages and that lymph node invasion (LNI) was greater. No differences were seen between the 3 groups in terms of local recurrence-free survival (RFS) and overall survival (OS) rates . In multivariate analysis, it was found that MF and MC tumours had no impact on local recurrence and OS. In multivariate analysis, it was understood that HER2 positivity and triple-negative breast cancer (TNBC) had an impact on local recurrence, and age, lymphovascular invasion (LVI), T3 tumour, lymph node positivity and TNBC subtype had an impact on OS.

CONCLUSION

Although MC and MF tumours show aggressive features such as high lymph node positivity and LVI, they have similar loco-regional recurrence and survival rates to UF tumours.

Design of Photosensitizing Agents for Targeted Antimicrobial Photodynamic Therapy

Photodynamic inactivation of microorganisms has gained substantial attention due to its unique mode of action, in which pathogens are unable to generate resistance, and due to the fact that it can be applied in a minimally invasive manner. In photodynamic therapy (PDT), a non-toxic photosensitizer (PS) is activated by a specific wavelength of light and generates highly cytotoxic reactive oxygen species (ROS) such as superoxide (O2-, type-I mechanism) or singlet oxygen (1O2*, type-II mechanism). Although it offers many advantages over conventional treatment methods, ROS-mediated microbial killing is often faced with the issues of accessibility, poor selectivity and off-target damage. Thus, several strategies have been employed to develop target-specific antimicrobial PDT (aPDT). This includes conjugation of known PS building-blocks to either non-specific cationic moieties or target-specific antibiotics and antimicrobial peptides, or combining them with targeting nanomaterials. In this review, we summarise these general strategies and related challenges, and highlight recent developments in targeted aPDT.

Time-Resolved Spectroscopy of Fluorescence Quenching in Optical Fibre-Based pH Sensors

Numerous optodes, with fluorophores as the chemical sensing element and optical fibres for light delivery and collection, have been fabricated for minimally invasive endoscopic measurements of key physiological parameters such as pH. These flexible miniaturised optodes have typically attempted to maximize signal-to-noise through the application of high concentrations of fluorophores. We show that high-density attachment of carboxyfluorescein onto silica microspheres, the sensing elements, results in fluorescence energy transfer, manifesting as reduced fluorescence intensity and lifetime in addition to spectral changes. We demonstrate that the change in fluorescence intensity of carboxyfluorescein with pH in this "high-density" regime is opposite to that normally observed, with complex variations in fluorescent lifetime across the emission spectra of coupled fluorophores. Improved understanding of such highly loaded sensor beads is important because it leads to large increases in photostability and will aid the development of compact fibre probes, suitable for clinical applications. The time-resolved spectral measurement techniques presented here can be further applied to similar studies of other optodes.

Molecular detection of Gram-positive bacteria in the human lung through an optical fiber-based endoscope

Purpose

The relentless rise in antimicrobial resistance is a major societal challenge and requires, as part of its solution, a better understanding of bacterial colonization and infection. To facilitate this, we developed a highly efficient no-wash red optical molecular imaging agent that enables the rapid, selective, and specific visualization of Gram-positive bacteria through a bespoke optical fiber–based delivery/imaging endoscopic device.

Methods

We rationally designed a no-wash, red, Gram-positive-specific molecular imaging agent (Merocy-Van) based on vancomycin and an environmental merocyanine dye. We demonstrated the specificity and utility of the imaging agent in escalating in vitro and ex vivo whole human lung models (n = 3), utilizing a bespoke fiber–based delivery and imaging device, coupled to a wide-field, two-color endomicroscopy system.

Results

The imaging agent (Merocy-Van) was specific to Gram-positive bacteria and enabled no-wash imaging of S. aureus within the alveolar space of whole ex vivo human lungs within 60 s of delivery into the field-of-view, using the novel imaging/delivery endomicroscopy device.

Conclusion

This platform enables the rapid and specific detection of Gram-positive bacteria in the human lung.

Electronic supplementary material

The online version of this article (10.1007/s00259-020-05021-4) contains supplementary material, which is available to authorized users.

Polymyxin-based photosensitizer for the potent and selective killing of Gram-negative bacteria

The methylene blue-polymyxin conjugate demonstrated high selectivity, sensitivity and phototoxicity against Gram-negative bacteria, including in early biofilm models.

EPR studies of intermolecular interactions and competitive binding of drugs in a drug-BSA binding model

Understanding intermolecular interactions between drugs and proteins is very important in drug delivery studies. Here, we studied different binding interactions between salicylic acid and bovine serum albumin (BSA) using electron paramagnetic resonance (EPR) spectroscopy. Salicylic acid was labeled with a stable radical (spin label) in order to monitor its mobilized (free) or immobilized (bound to BSA) states. In addition to spin labeled salicylic acid (SL-salicylic acid), its derivatives including SL-benzoic acid, SL-phenol, SL-benzene, SL-cyclohexane and SL-hexane were synthesized to reveal the effects of various drug binding interactions. EPR results of these SL-molecules showed that hydrophobic interaction is the main driving force. Whereas each of the two functional groups (-COOH and -OH) on the benzene ring has a minute but detectable effect on the drug-protein complex formation. In order to investigate the effect of electrostatic interaction on drug binding, cationic BSA (cBSA) was synthesized, altering the negative net charge of BSA to positive. The salicylic acid loading capacity of cBSA is significantly higher compared to that of BSA, indicating the importance of electrostatic interaction in drug binding. Moreover, the competitive binding properties of salicylic acid, ibuprofen and aspirin to BSA were studied. The combined EPR results of SL-salicylic acid/ibuprofen and SL-ibuprofen/salicylic acid showed that ibuprofen is able to replace up to ∼83% of bound SL-salicylic acid, and salicylic acid can replace only ∼14% of the bound SL-ibuprofen. This indicates that ∼97% of all salicylic acid and ibuprofen binding sites are shared. On the other hand, aspirin replaces only ∼23% of bound SL-salicylic acid, and salicylic acid replaces ∼50% of bound SL-aspirin, indicating that ∼73% of all salicylic acid and aspirin binding sites are shared. These results show that EPR spectroscopy in combination with the spin labeling technique is a very powerful method to investigate drug binding dynamics in detail.

Physiological concentrations of albumin favor drug binding

We exploit the direct measurements of spin labeled drugs to study drug binding to/release from protein using EPR spectroscopy.