BODIPY dyes for optical limiting applications on the nanosecond timescale.

Since 2017, the Institute for Nanotechnology Innovation at Rhodes University has studied the optical limiting properties of boron dipyrromethene (BODIPY) dyes with respect to high-intensity nanosecond timescale laser pulses. Concerns over the irresponsible use of laser pointers in the context of aviation safety have provided a need for materials that can readily transmit light under ambient conditions while rapidly attenuating intense incident laser pulses. The structural flexibility of the BODIPY chromophore facilitates the red shift of the main BODIPY spectral band that typically lies at 500 nm to the red end of the visible and the near-infrared through the introduction of vinylene groups at the 3,5-positions or an aza-nitrogen atom.

3D-printed electrochemical cells for multi-point aptamer-based drug measurements.

Electrochemical aptamer-based (E-AB) sensors achieve detection and quantitation of biomedically relevant targets such as small molecule drugs and protein biomarkers in biological samples. E-ABs are usually fabricated on commercially available macroelectrodes which, although functional for rapid sensor prototyping, can be costly and are not compatible with the microliter sample volumes typically available in biorepositories for clinical validation studies. Seeking to develop a multi-point sensing platform for sensor validation in sample volumes characteristic of clinical studies, we report a protocol for in-house assembly of 3D-printed E-ABs.

Blue-Light-Activated Water-Soluble Sn(IV)-Porphyrins for Antibacterial Photodynamic Therapy (aPDT) against Drug-Resistant Bacterial Pathogens.

Antimicrobial resistance has emerged as a global threat to the treatment of infectious diseases. Antibacterial photodynamic therapy (aPDT) is a promising alternative approach and is highly suitable for the treatment of cutaneous bacterial infections through topical applications. aPDT relies on light-responsive compounds called photosensitizer (PS) dyes, which generate reactive oxygen species (ROS) when induced by light, thereby killing bacterial cells.

Selective Generation of V2 Silicon Vacancy Centers in 4H-Silicon Carbide.

The deterministic generation of individual color centers with defined orientations or types in solid-state systems is paramount for advancements in quantum technologies. Silicon vacancies in 4H-silicon carbide (4H-SiC) can be formed in V1 and V2 types. However, silicon vacancies are typically generated randomly between V1 and V2 types with similar probabilities.

Analytical Validation of Aptamer-Based Serum Vancomycin Monitoring Relative to Automated Immunoassays.

The practice of monitoring therapeutic drug concentrations in patient biofluids can significantly improve clinical outcomes while simultaneously minimizing adverse side effects. A model example of this practice is vancomycin dosing in intensive care units. If dosed correctly, vancomycin can effectively treat methicillin-resistant streptococcus aureus (MRSA) infections.

The photodynamic activity properties of a series of structurally analogous tetraarylporphyrin, chlorin and N-confused porphyrin dyes and their Sn(IV) complexes.

A series of tetraarylporphyrin, -chlorin and N-confused porphyrin dyes with 4‑methoxy‑meso-aryl rings (1-Por, 1-Chl and 1-NCP) and their Sn(IV) complexes (1-SnPor, 1-SnChl and 1-SnNCP) have been synthesized and characterized. The heavy atom effect of the Sn(IV) ion results in relatively high singlet oxygen quantum yield values of 0.67, 0.

The Photodynamic Anticancer and Antibacterial Activity Properties of a Series of -Tetraarylchlorin Dyes and Their Sn(IV) Complexes.

A series of tetraarylchlorins with 3-methoxy-, 4-hydroxy- and 3-methoxy-4-hydroxyphenyl -aryl rings (--Chl) and their Sn(IV) complexes (--SnChl) were synthesized and characterized so that their potential utility as photosensitizer dyes for use in photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) can be assessed. The photophysicochemical properties of the dyes were assessed prior to in vitro PDT activity studies against MCF-7 breast cancer cells through irradiation with Thorlabs 625 or 660 nm LED for 20 min (240 or 280 mW·cm). PACT activity studies were performed against both planktonic bacteria and biofilms of Gram-(+) and Gram-(-) upon irradiation with Thorlabs 625 and 660 nm LEDs for 75 min.

Alleviation of thermal nociception depends on heat-sensitive neurons and a TRP channel in the brain.

Acute avoidance of dangerous temperatures is critical for animals to prevent or minimize injury. Therefore, surface receptors have evolved to endow neurons with the capacity to detect noxious heat so that animals can initiate escape behaviors. Animals including humans have evolved intrinsic pain-suppressing systems to attenuate nociception under some circumstances.

Sn(IV)-porphyrinoids for photodynamic anticancer and antimicrobial chemotherapy.

Photodynamic therapy (PDT) is a mode of treatment for different types of cancers, which involves a nontoxic photosensitizer (PS), a light source to activate the PS, and ground-state molecular oxygen (O). Light activation of the PS leads to the generation of reactive oxygen species (ROS), which initiates a toxic effect on the surrounding cellular substrates, thereby destroying the cancerous cells. The commercially used PDT drug Photofrin which is a tetrapyrrolic porphyrin-based photosensitizer has drawbacks such as aggregation in water, prolonged skin photosensitivity, variability in chemical compositions, and minimal absorbance in the red-light region.

Alkaline taste sensation through the alkaliphile chloride channel in Drosophila.

The sense of taste is an important sentinel governing what should or should not be ingested by an animal, with high pH sensation playing a critical role in food selection. Here we explore the molecular identities of taste receptors detecting the basic pH of food using Drosophila melanogaster as a model. We identify a chloride channel named alkaliphile (Alka), which is both necessary and sufficient for aversive taste responses to basic food.

Methylthiophenyl- and Methylthiobiphenyl-Substituted AB Cocorroles: Modulating Electrocatalyzed Hydrogen Evolution Reactions on Surface-Modified Gold Electrodes.

Four AB-type Cocorroles () with electron-donating/withdrawing substituents at the A -aryl substituents and a 4-(methylthio)phenyl ring at the B position have been synthesized and characterized, along with a series of -extended Cocorroles (-) with 4'-(methylthio)biphenyl moieties. The electronic structures and structure-property relationships of the dyes have been analyzed by comparing their redox and optical properties to trends predicted in density functional theory calculations. Au electrodes surface-modified with - and - are highly efficient catalysts for electrocatalyzed hydrogen evolution reactions, and the electrocatalytic properties can be readily modulated by fine-tuning the electronic structure of the Cocorrole and the distance between the "Au-S" bond and Co center.

A hypoxia responsive silicon phthalocyanine containing naphthquinone axial ligands for photodynamic therapy activity.

A liposome loaded‑silicon (IV) phthalocyanine (SiPc) containing naphthoquinone axial ligands as hypoxia-responsive a prodrug-like moieties (Prodrug-SiPc), is herein reported. With the help of computational methods, this study assessed the photophysical, photochemical and electrochemical redox properties of the Prodrug-SiPc to elucidate the relationship between material structure and properties. The attachment of the axial quinoid moieties endowed the Prodrug-SiPc with Type I/II photochemical and prodrug-like properties.

Photophysical and in vitro photoinactivation of Escherichia coli using cationic 5,10,15,20-tetra(pyridin-3-yl) porphyrin and Zn(II) derivative conjugated to graphene quantum dots.

Pathogenic microorganisms may continue causing infection through the transfer of antibiotic resistance genes. As a result, the efficacy of pharmaceuticals in microbial inactivation is deteriorating. The present study was conducted to investigate the antimicrobial activity of neutral and quaternized free base and Zn 5,10,15,20-tetra(pyridin-3-yl) porphyrins on Escherichia coli (E.

Diiodinated Mono- and Dipyridylvinyl BODIPY Dyes: Photophysicochemical Properties, in vitro Antibacterial Studies, Molecular Docking and Theoretical Calculations.

In this study, novel mono- and dipyridylvinyl boron dipyrromethene dyes are prepared to compare their photodynamic antimicrobial chemotherapy (PACT) activities against Staphylococcus aureus to the corresponding core dyes. Pyridylvinyl substitution at the 3- or 3,5-positions of a meso-4-bromophenylBODIPY core dye via a Knoevenagel reaction with an aromatic 2-bromopyridinecarboxaldehyde shifts the major BODIPY spectral band to longer wavelength. The extended π-conjugation red shifts the main spectral band into the 602-618 nm region in CHCl , THF, ethanol and DMSO after monopyridylvinyl substitution and to 685-704 nm after dipyridylvinyl substitution.

Promotion of Catalytic Oxygen Reduction Reactions: The Utility of Proton Management Substituents on Cobalt Porphyrins.

Three ABAB-type cobalt -tetraarylporphyrins with fluorine (), acetic acid (), and cyanoacetic acid () groups at the -positions of phenyl rings at the 10,20-positions are synthesized and evaluated as catalysts for oxygen reduction reactions (ORRs). In density functional theory calculations, the frontier molecular orbitals of these complexes were found to be stabilized relative to model complexes with electron-withdrawing atoms or moieties on the -aryl rings. Electrochemical measurements suggest that electrodes with ( exhibit the most positive ORR potential values and the highest limiting current density in both acidic and alkali electrolytes, while the electrocatalyst exhibits extremely low ORR performance.

Gatriarylcorroles with push-pull substitutions: synthesis, electronic structure and biomedical applications.

Two AB type Hcorroles and two Gatriarylcorroles with carbazole substitutions at 10-positions were synthesized and characterized. An analysis of structure-property relationships of the corroles has been carried out by investigating the optical spectroscopy of the dyes to trends predicted in DFT and TD-DFT calculations. Interestingly, the photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) activity properties of the Gatriarylcorroles were determined against the MCF-7 breast cancer line, and () and (), respectively.

Microneedle Aptamer-Based Sensors for Continuous, Real-Time Therapeutic Drug Monitoring.

The ability to continuously monitor the concentration of specific molecules in the body is a long-sought goal of biomedical research. For this purpose, interstitial fluid (ISF) was proposed as the ideal target biofluid because its composition can rapidly equilibrate with that of systemic blood, allowing the assessment of molecular concentrations that reflect full-body physiology. In the past, continuous monitoring in ISF was enabled by microneedle sensor arrays.

Photodynamic Antitumor and Antimicrobial Activities of Free-Base Tetra(4-methylthiolphenyl)chlorin and Its Tin(IV) Complex.

Meso-tetra(4-methylthiolphenyl)chlorin (3) and its Sn(IV) complex (3-Sn) have been synthesized and characterized. The heavy atom effects of the Sn(IV) ion and sulfur atoms result in relatively high singlet oxygen quantum yield values of 0.40 and 0.

Low-Symmetry Phthalocyanines Bearing Carboxy-Groups: Synthesis, Spectroscopic and Quantum-Chemical Characterization.

The synthesis and characterization of AB-type phthalocyanines, -, bearing bulky 2,6-diisopropylphenoxy-groups or chlorine atoms on isoindoline units "A" and either one or two carboxylic anchors on isoindoline unit "B" are reported. A comparison of molecular modelling with the conventional time dependent-density functional theory (TD-DFT) approach and its simplified sTD-DFT approximation provides further evidence that the latter method accurately reproduces the key trends in the spectral properties, providing colossal savings in computer time for quite large molecules. This demonstrates that it is a valuable tool for guiding the rational design of new phthalocyanines for practical applications.

Quantitative Hg detection via forming three coordination complexes using a lysosome targeting quinoline - Fisher aldehyde fluorophore.

This work describes (Z)-N-((Z)-2-(1,3,3-trimethylindolin-2ylidene)ethylidene)quinoline-8-amine (LYSO-QF), a high-performing and biocompatible dye comprised of quinoline and Fisher aldehyde moieties linked via an imine vinyl backbone with lysosome targeting ability that can be used to quantitatively detect the mercury ion (Hg) in biosystems and the natural environment. This is achieved by forming three different tetrameric, trimeric and dimeric complexes between Hg and LYSO-QF with the limit of detection (LOD) of 11 nm. The complexes formed were analyzed with the aid of time-dependent density functional theory (TD-DFT) calculations.

A simple quinoline-thiophene Schiff base turn-off chemosensor for Hg detection: spectroscopy, sensing properties and applications.

A new Schiff base probe (QT) consisting of 8-aminoquinoline (Q) and thiophene-2-carboxaldehyde (T) moieties has been synthesized. QT undergoes chelation-enhanced fluorescence quenching when exposed to Hg due to coordination by the sulfur and nitrogen atoms of QT thus forming a facile "turn-off" sensor. The formation of the chelation complex was confirmed by UV-visible absorption and emission spectral measurements, H NMR titration and density functional theory calculations.

Cognitive behavioral therapy for depressive disorders: Outcomes from a multi-state, multi-site primary care practice.

Background: Individuals with depressive disorders often present to and seek treatment in primary care. Integrated behavioral health services within this setting can improve access to evidence-based cognitive behavioral therapy (CBT). However, limited information exists on the effectiveness of CBT for depression in primary care.

Molecular and cellular basis of acid taste sensation in Drosophila.

Acid taste, evoked mainly by protons (H), is a core taste modality for many organisms. The hedonic valence of acid taste is bidirectional: animals prefer slightly but avoid highly acidic foods. However, how animals discriminate low from high acidity remains poorly understood.

Positively charged styryl pyridine substituted Zn(II) phthalocyanines for photodynamic therapy and photoantimicrobial chemotherapy: effect of the number of charges.

Cationic Zn phthalocyanine complexes were synthesized using Knoevenagel reaction starting from a Zn(ii) tetrakis(2-formylphenoxy)phthalocyanine (1) to form Zn(ii) tetrakis(1-butyl-4-(4-(tetraphenoxy)styryl)pyridin-1-ium) phthalocyanine (2) and Zn(ii) tetrakis(4-(4-(tetraphenoxy)styryl)-1-(4-(triphenylphosphonio)butyl)pyridin-1-ium)phthalocyanine (3). The photophysicochemical behaviours of the Pc complexes were assessed. The cationic complexes display high water-solubility and gave moderate singlet oxygen quantum yield in water.