A triphenylamine-based aggregation-enhanced emission probe for viscosity and polarity analysis of lubricating oils

Lubricating oil offers abundant information about the operating state of machine. In this work, a donor-acceptor aggregation-enhanced emission fluorescent molecule, (Z)-4-(1-cyano-2-(4-(diphenylamino)phenyl)vinyl)benzonitrile (CPA-TPA), was synthesized to investigate its function to sense...

Reaction-based fluorescence probes for “turn on” sensing fluoride ions

Introducing a weak covalent bond into an originally highly fluorescent molecule to create a non-fluorescent probe is able to afford a new way to detect some neucleophilic targets with enhanced...

On the Acoustic Response of Ultrasonically - stimulated microbubbles and Enhanced Intracellular Uptake of a Fluorescent Molecule

Effectiveness of ultrasound-and-microbubble mediated therapy depends on the acoustic response of microbubbles. In this study, the acoustic response of microbubbles in the absence and presence of cells is measured using integrated cavitation dose (ICD) over harmonics/ultraharmonics/broadband, and correlated with intracellular uptake of a fluorescent marker for varying peak-negative-pressures (PNPs). The ICD was independent of presence of cells. A PNP-threshold of 0.64 MPa was observed for microbubble’s inertial cavitation; stable cavitation (PNPs<0.64MPa) and inertial cavitation (PNPs≥0.64MPa) regimes were identified. Within inertial cavitation regime, a stronger correlation (R2>0.9) was observed between the ICD and FITC-positive cells, whereas, a weaker correlation, ranging from R2=0.59 at 3rd ultra-harmonic to R2 = 0.85 at 2nd ultra-harmonic, was observed under stable cavitation regime. The intracellular uptake, ICD and their correlation is dependent on microbubbles cavitation regime, indicating that ICD shows potential to predict bio-effects induced not only by inertial cavitation but also by stable cavitation of MBs.

On the Acoustic Response of Ultrasonically - stimulated microbubbles and Enhanced Intracellular Uptake of a Fluorescent Molecule

Effectiveness of ultrasound-and-microbubble mediated therapy depends on the acoustic response of microbubbles. In this study, the acoustic response of microbubbles in the absence and presence of cells is measured using integrated cavitation dose (ICD) over harmonics/ultraharmonics/broadband, and correlated with intracellular uptake of a fluorescent marker for varying peak-negative-pressures (PNPs). The ICD was independent of presence of cells. A PNP-threshold of 0.64 MPa was observed for microbubble’s inertial cavitation; stable cavitation (PNPs<0.64MPa) and inertial cavitation (PNPs≥0.64MPa) regimes were identified. Within inertial cavitation regime, a stronger correlation (R2>0.9) was observed between the ICD and FITC-positive cells, whereas, a weaker correlation, ranging from R2=0.59 at 3rd ultra-harmonic to R2 = 0.85 at 2nd ultra-harmonic, was observed under stable cavitation regime. The intracellular uptake, ICD and their correlation is dependent on microbubbles cavitation regime, indicating that ICD shows potential to predict bio-effects induced not only by inertial cavitation but also by stable cavitation of MBs.

pH-Responsive Self-Assembly of Designer Aromatic Peptide Amphiphiles and Enzymatic Post-Modification of Assembled Structures

Supramolecular fibrous materials in biological systems play important structural and functional roles, and therefore, there is a growing interest in synthetic materials that mimic such fibrils, especially those bearing enzymatic reactivity. In this study, we investigated the self-assembly and enzymatic post-modification of short aromatic peptide amphiphiles (PAs), Fmoc-LnQG (n = 2 or 3), which contain an LQG recognition unit for microbial transglutaminase (MTG). These aromatic PAs self-assemble into fibrous structures via π-π stacking interactions between the Fmoc groups and hydrogen bonds between the peptides. The intermolecular interactions and morphologies of the assemblies were influenced by the solution pH because of the change in the ionization states of the C-terminal carboxy group of the peptides. Moreover, MTG-catalyzed post-modification of a small fluorescent molecule bearing an amine group also showed pH dependency, where the enzymatic reaction rate was increased at higher pH, which may be because of the higher nucleophilicity of the amine group and the electrostatic interaction between MTG and the self-assembled Fmoc-LnQG. Finally, the accumulation of the fluorescent molecule on these assembled materials was directly observed by confocal fluorescence images. Our study provides a method to accumulate functional molecules on supramolecular structures enzymatically with the morphology control.

Ratiometric Fluorescence Assay for Nitroreductase Activity: Locked-Flavylium Fluorophore as a NTR-Sensitive Molecular Probe

Nitroreductases belong to a member of flavin-containing enzymes that can reduce nitroaromatic compounds to amino derivatives with NADH as an electron donor. NTR activity is known to be elevated in the cancerous environment and is considered an advantageous target in therapeutic prodrugs for the treatment of cancer. Here, we developed a ratiometric fluorescent molecule for observing NTR activity in living cells. This can provide a selective and sensitive response to NTR with a distinct increase in fluorescence ratio (FI530/FI630) as well as color changes. We also found a significant increase in NTR activity in cervical cancer HeLa and lung cancer A549 cells compared to non-cancerous NIH3T3. We proposed that this new ratiometric fluorescent molecule could potentially be used as a NTR-sensitive molecular probe in the field of cancer diagnosis and treatment development related to NTR activity.

Mitochondria-targeting fluorescent sensor for on-off-on response to Cu2+ and ATP in cells and zebrafish

Cupric ion (Cu2+) and adenosine triphosphate (ATP) are functionally important in mitochondria and play essential roles in many important biological processes. In this work, a mitochondria-targeting fluorescent molecule Mito-A was...