Exploring the effect of photobiomodulation and gamma visual stimulation induced by 808 nm and visible LED in Alzheimer's disease mouse model.

Although photobiomodulation (PBM) and gamma visual stimulatqion (GVS) have been overwhelmingly explored in the recent time as a possible light stimulation (LS) means of Alzheimer's disease (AD) therapy, their effects have not been assessed at once. In our research, the AD mouse model was stimulated using light with various parameters [continuous wave (PBM) or 40 Hz pulsed visible LED (GVS) or 40 Hz pulsed 808 nm LED (PBM and GVS treatment)]]. The brain slices collected from the LS treated AD model mice were evaluated using (i) fluorescence microscopy to image thioflavine-S labeled amy-loid-β (Aβ) plaques (the main hallmark of AD), or (ii) two-photon excited fluorescence (TPEF) imaging of unlabeled Aβ plaques, showing that the amount of Aβ plaques was reduced after LS treatment.

Xanthene, cyanine, oxazine and BODIPY: the four pillars of the fluorophore empire for super-resolution bioimaging.

In the realm of biological research, the invention of super-resolution microscopy (SRM) has enabled the visualization of ultrafine sub-cellular structures and their functions in live cells at the nano-scale level, beyond the diffraction limit, which has opened up a new window for advanced biomedical studies to unravel the complex unknown details of physiological disorders at the sub-cellular level with unprecedented resolution and clarity. However, most of the SRM techniques are highly reliant on the personalized special photophysical features of the fluorophores. In recent times, there has been an unprecedented surge in the development of robust new fluorophore systems with personalized features for various super-resolution imaging techniques.

Synergistic photobiomodulation with 808-nm and 1064-nm lasers to reduce the β-amyloid neurotoxicity in the Alzheimer's disease models.

Background: In Alzheimer's disease (AD), the deposition of β-amyloid (Aβ) plaques is closely associated with the neuronal apoptosis and activation of microglia, which may result in the functional impairment of neurons through pro-inflammation and over-pruning of the neurons. Photobiomodulation (PBM) is a non-invasive therapeutic approach without any conspicuous side effect, which has shown promising attributes in the treatment of chronic brain diseases such as AD by reducing the Aβ burden. However, neither the optimal parameters for PBM treatment nor its exact role in modulating the microglial functions/activities has been conclusively established yet.

Recent advances in plasmon-enhanced luminescence for biosensing and bioimaging.

Plasmon-enhanced luminescence (PEL) is a unique photophysical phenomenon in which the interaction between luminescent moieties and metal nanostructures results in a marked luminescence enhancement. PEL offers several advantages and has been extensively used to design robust biosensing platforms for luminescence-based detection and diagnostics applications, as well as for the development of many efficient bioimaging platforms, enabling high-contrast non-invasive real-time optical imaging of biological tissues, cells, and organelles with high spatial and temporal resolution. This review summarizes recent progress in the development of various PEL-based biosensors and bioimaging platforms for diverse biological and biomedical applications.

Long-Term Repeatable In Vivo Monitoring of Amyloid-β Plaques and Vessels in Alzheimer's Disease Mouse Model with Combined TPEF/CARS Microscopy.

Long-term, repeatable monitoring of the appearance and progress of Alzheimer's disease (AD) in real time can be extremely beneficial to acquire highly reliable diagnostic insights, which is crucial for devising apt strategies towards effective AD treatment. Herein, we present an optimized innovative cranial window imaging method for the long-term repeatable imaging of amyloid-β (Aβ) plaques and vessels in an AD mouse model. Basically, two-photon excitation fluorescence (TPEF) microscopy was used to monitor the fluorescently labeled Aβ plaques, whereas the label-free blood vessels were studied using coherent anti-Stokes Raman scattering (CARS) microscopy in the live in vivo AD mouse model.

Improving the performance of rapid lifetime determination for wide-field time-gated imaging in live cells.

In biological research, rapid wide-field fluorescence lifetime imaging has become an important imaging tool. However, the biological samples with weak fluorescence signals and lower sensitivity often suffer from very low precision in lifetime determinations which restricts its widespread utilization in many bioimaging applications. To address this issue, a method is presented in this paper to substantially enhance the precision of rapid lifetime determination (RLD).

Super-resolution Microscopy for Biological Imaging.

Studying the ultra-fine structures and functions of the subcellular organelles and exploring the dynamic biological events in depth are the key issues in contemporary biological research. Fluorescence bio-imaging has been used to study cell biology for decades. However, the structures and functions of the subcellular organelles which fall under the diffraction limit are still not explored fully at a nanoscale level.

AIE-active two-photon fluorescent nanoprobe with NIR-II light excitability for highly efficient deep brain vasculature imaging.

Aggregation induced emission (AIE)-active bright two-photon fluorescent probes with second near-infrared (NIR-II) light excitability can be used for efficient brain bioimaging studies, wherein the fabrication of water-dispersible nanoparticles by encapsulating the hydrophobic probes with amphiphilic polymer holds the key to ensuring biocompatibility and adaptability. However, barely any study has evaluated the structural requirements that can substantially affect the water-dispersible nanoparticle formation ability of an organic AIE-active dye with amphiphilic polymers. The present study systematically assessed the structural dependency of a well-known acrylonitrile based AIE system/fluorogenic core upon the formation of water-dispersible nanoparticles and elucidated how the structural modifications can impact the two-photon imaging.

Solo Smart Fluorogenic Probe for Potential Cancer Diagnosis and Tracking in Vivo Tumorous Lymphatic Systems via Distinct Emission Signals.

A versatile twisted-intramolecular-charge-transfer (TICT)-based near-infrared (NIR) fluorescent probe () has been judiciously designed and synthesized that could be utilized for potential cancer diagnosis and to track lymph node(s) in mice through distinct emission signals. Essentially, the probe rendered the capability to preferentially recognize the cancer cells over the noncancer cells by polarity-guided lipid droplet specific differential bioimaging (in green emission channel) studies. The probe also exhibited selective turn-on fluorescence response toward HSA/BSA in physiological media (aqueous PBS buffer; pH 7.

Redefining the photo-stability of common fluorophores with triplet state quenchers: mechanistic insights and recent updates.

Light microscopy can offer certain advantages over electron microscopy in terms of acquiring detailed insights into the biological/intra-cellular milieu. In recent years, with the development of new fluorescence imaging technologies, it has become extremely important to assess the role of designing appropriate fluorophores in acquiring desired biological information without encountering any untoward hitches. Over the years, external fluorophores have been prevalently used in fluorescence microscopy and single-molecule fluorescence microscopy-based studies.

Exploring the potential of a urea derivative: an AIE-luminogen and its interaction with human serum albumin in aqueous medium.

A urea derivative L1 exhibits Aggregation-Induced Emission (AIE) activity in an acetonitrile-water mixed solvent. The aggregation phenomenon has been corroborated by microscopy and light scattering studies. The ligand (L1) also displays a selective turn-on fluorescence response towards human serum albumin (HSA) in 100% aqueous medium over various other comparable proteins (even bovine serum albumin (BSA)) and enzymes.

Al sensing through different turn-on emission signals vis-à-vis two different excitations: Applications in biological and environmental realms.

A rationally designed Schiff base chemosensor (L) could render specific detection of Al ions with two distinct turn-on emission signals, separated by over 100 nm upon excitation at two different wavelengths. The utility of the probe lies in facilitating sensing in 80% aqueous medium with an emission close to 600 nm via an intramolecular charge transfer (ICT) mechanism. The biocompatible and cell permeable probe could readily sense Al in live HeLa cells as well.

Twisted-Intramolecular-Charge-Transfer-Based Turn-On Fluorogenic Nanoprobe for Real-Time Detection of Serum Albumin in Physiological Conditions.

Two cyanine-based fluorescent probes, ( E)-2-(4-(diethylamino)-2-hydroxystyryl)-3-ethyl-1,1-dimethyl-1 H-benzo[ e]indol-3-ium iodide (L) and ( E)-3-ethyl-1,1-dimethyl-2-(4-nitrostyryl)-1 H-benzo[ e]indol-3-ium iodide (L), have been designed and synthesized. Of these two probes, the twisted-intramolecular-charge-transfer (TICT)-based probe, L, can preferentially self-assemble to form nanoaggregates. L displayed a selective turn-on fluorescence response toward human and bovine serum albumin (HSA and BSA) in ∼100% aqueous PBS medium, which is noticeable with the naked eye, whereas L failed to sense these albumin proteins.

A ratiometric fluorogenic probe for the real-time detection of SO in aqueous medium: application in a cellulose paper based device and potential to sense SO in mitochondria.

A new water soluble and fluorogenic probe (L) that can demonstrate a specific ratiometric detection of a SO derivative (SO) in 100% aqueous medium and live cells has been designed and synthesized. The detection process can be visualized by the naked eye, as the orange-red fluorescence of L turns into a strong blue fluorescence upon interaction with SO. L displayed several beneficial attributes such as detection in complete aqueous medium, extremely fast response time along with high selectivity and sensitivity.

Fixation of atmospheric CO as novel carbonate-(water)-carbonate cluster and entrapment of double sulfate within a linear tetrameric barrel of a neutral bis-urea scaffold.

A meta-phenylenediamine-based disubstituted bis-urea receptor L1 with electron-withdrawing 3-chloro and electron-donating 4-methylphenyl terminals has been established as a potential system to fix and efficiently capture atmospheric CO as air-stable entrapment of an unprecedented {CO-(HO)-CO} cluster (complex 1a) within its tetrameric long straight pillar-like assembly entirely sealed by n-TBA cations via formation of a barrel-type architecture. L1 and its isomeric 4-bromo-3-methyl disubstituted bis-urea receptor L2 have been found to entrap similar kinds of water-free naked sulfate-sulfate double anion (complexes 1b and 2a) by cooperative binding of urea moieties inside the two pairs of the inversion-symmetric linear tetrameric barrel of L1 and L2, respectively. On the other hand, in the presence of excess halides, L1 self-assembles to form hexa-coordinated fluoride complex 1c and tetra-coordinated bromide complex 1d, while L2 self-assembles to form penta-coordinated fluoride complex 2b in the solid state via semicircular receptor architectures and non-cooperative H-bonding interactions of urea moieties.

A solo fluorogenic probe for the real-time sensing of SO3(2-) and SO4(2-)/HSO4(-) in aqueous medium and live cells by distinct turn-on emission signals.

A judiciously designed fluorogenic probe (L) rendered rapid and differential turn-on responses by exhibiting strong blue fluorescence (λem = 442 nm) for SO3(2-) and greenish-yellow fluorescence (λem = 511 nm) for SO4(2-)/HSO4(-) in 100% aqueous medium and live cells.

A multi-responsive turn-on flurogenic probe to sense Zn(2+), Cd(2+) and Pb(2+): left-right-center emission signal swing.

A versatile new fluorogenic Schiff base probe (L) has been synthesized by the reaction of quinoline-2-carbohydrazide (which acts as the chelating site) and 4-dimethylamino cinnamaldehyde (which acts as the signaling unit). L can sense three of the most biologically and environmentally important metal ions, Zn(2+), Cd(2+) and Pb(2+), among various tested metal ions through selective TURN-ON fluorescence responses in physiological pH. Interestingly, L can not only sense Zn(2+), Cd(2+) and Pb(2+) fluorometrically in physiological conditions but can also distinguish one from another by exhibiting individual intrinsic left-right-center TURN-ON emission signal swings.

An aggregation-induced emission (AIE) active probe for multiple targets: a fluorescent sensor for Zn(2+) and Al(3+) & a colorimetric sensor for Cu(2+) and F(-).

A rationally designed probe L, which consists of both cation and anion binding sites, is capable of displaying interesting aggregation induced emission (AIE) properties. L not only can sense Al(3+) and Zn(2+) through selective turn-on fluorescence responses in 9 : 1 methanol-HEPES buffer (5 mM, pH 7.3; 9 : 1, v/v) medium due to metal ion triggered AIE activity, but also can distinguish them through individual emission signals.

A zinc complex of a neutral pyridine-based amphiphile: a highly efficient and potentially therapeutic bactericidal material.

The alarming rise in antibiotic-resistant pathogenic bacteria demands a prudent approach in the generation of therapeutic antibacterials. The present study illustrates the development of a potent amphiphilic bactericidal material tailored to leverage interactions with metal-reactive groups (MRGs) present in the bacterial cell surface envelope. Complexation of Zn(ii) with a neutral pyridine-based synthetic amphiphile (C1) generated the cationic C1-Zn, which exhibited manyfold higher membrane-directed bactericidal activity compared to the neutral C1, or the cationic amphiphile bearing two pyridinium head groups (C2).

Colorimetric and fluorometric discrimination of geometrical isomers (maleic acid vs fumaric acid) with real-time detection of maleic acid in solution and food additives.

Heterobis imine Schiff base probe L is able to discriminate geometrical isomers (maleic acid vs fumaric acid) through sharp colorimetric as well as fluorogenic responses even conspicuous with the naked eye. Colorimetric as well as fluorogenic sensing of maleic acid among various carboxylic acids was also demonstrated in ethanol-buffer medium. Sensing behavior of L was corroborated by (1)H NMR spectra, mass spectrometry, and theoretical calculations.

A single probe to sense Al(III) colorimetrically and Cd(II) by turn-on fluorescence in physiological conditions and live cells, corroborated by X-ray crystallographic and theoretical studies.

A pyridine-2-carbohydrazide functionalized conjugated fluorophoric Schiff base ligand (L₁) specifically senses Al(3+) and Cd(2+) ions through significant changes in its absorption and emission spectral behavior, respectively, in physiological conditions. The spectral changes are in the visible region of the spectrum and thus facilitate naked eye detection. Apart from the visible changes, an in-field device application was demonstrated by sensing these ions in paper strips coated with L₁.

An aggregation-induced emission (AIE) active probe renders Al(III) sensing and tracking of subsequent interaction with DNA.

An aggregation-induced emission (AIE) active probe (L) displayed TURN-ON fluorescence response toward Al(3+) under physiological conditions and in HeLa cells. The L-Al(3+) ensemble could subsequently facilitate tracking of interaction with DNA in solution.

A novel chemosensor with visible light excitability for sensing Zn2+ in physiological medium and in HeLa cells.

In the present study a novel imine-hydrazone based fluorescent chemosensor () for efficient and selective sensing of Zn(2+) over other biologically important metal ions under physiological conditions is reported. An enhancement in fluorescence emission intensity of the developed probe with a red shift of ∼25 nm was observed for Zn(2+), whereas other metal ions failed to reveal any significant change in the emission spectra. Interestingly, the receptor functioned under completely physiological conditions (99.