Surface embedded enhancement of fluorescence of coumarinyl-azo-imidazolium stabilized gold nanoparticles

316-323<span style="letter-spacing:-.1pt;mso-bidi-font-weight: bold" lang="EN-GB">Coumarinyl-azo-imidazole (CAI-H) undergoes double alkylation to yield 1, 3-dialkyl-2-(coumarinyl-6-azo)imidazolium bromide<span style="mso-bidi-font-weight: bold"> (CAI-(CnH2n+1)2+Br-) of long chain alkyl groups –CnH2n+1 (n = 6, 9, 12, 15, 18) attached to imidazolyl motif. These compounds are characterized by spectroscopic data (FT-IR, UV-vis and 1H NMR). The size of the gold nanoparticles stabilized with tetraoctylammonium bromide (avg size 20.5 nm) is reduced to 2–10 nm upon surface implantation of CAI-(CnH2n+1)2+; these have been characterized by FESEM/TEM. The spectroscopic investigation has established the stability of gold nanoparticles. The fluorescence emissivity of these nanoparticles is enhanced 10–25 folds as compared to free CAI-(CnH2n+1)2+Br–, which may be due to coupling of plasmonic band with emission of fluorescent dye molecules and the reduction of PET (Coumarin*→ Imidazolium) and vibrational relaxation of imidazolium coating on the gold nanoparticles surface. <span style="letter-spacing: -.1pt;mso-bidi-font-weight:bold" lang="EN-GB"> </span

Characterization of domain-specific interaction of synthesized dye with serum proteins by spectroscopic and docking approaches along with determination of in vitro cytotoxicity and antiviral activity

<p>The interaction between a synthesized dye with proteins, bovine, and human serum albumin (BSA, HSA, respectively) under physiological conditions has been characterized in detail, by means of steady-state and time-resolved fluorescence, UV–vis absorption, and circular dichroism (CD) techniques. An extensive time-resolved fluorescence spectroscopic characterization of the quenching process has been undertaken in conjugation with temperature-dependent fluorescence quenching studies to divulge the actual quenching mechanism. From the thermodynamic observations, it is clear that the binding process is a spontaneous molecular interaction, in which van der Waals and hydrogen bonding interactions play the major roles. The UV–vis absorption and CD results confirm that the dye can induce conformational and micro-environmental changes of both the proteins. In addition, the dye binding provokes the functionality of the native proteins in terms of esterase-like activity. The average binding distance (<i>r</i>) between proteins and dye has been calculated using FRET. Cytotoxicity and antiviral effects of the dye have been found using Vero cell and <b>HSV-1F</b> virus by performing MTT assay. The AutoDock-based docking simulation reveals the probable binding location of dye within the sub-domain IIA of HSA and IB of BSA.</p

Characterization of domain-specific interaction of synthesized dye with serum proteins by spectroscopic and docking approaches along with determination of in vitro cytotoxicity and antiviral activity

<p>The interaction between a synthesized dye with proteins, bovine, and human serum albumin (BSA, HSA, respectively) under physiological conditions has been characterized in detail, by means of steady-state and time-resolved fluorescence, UV–vis absorption, and circular dichroism (CD) techniques. An extensive time-resolved fluorescence spectroscopic characterization of the quenching process has been undertaken in conjugation with temperature-dependent fluorescence quenching studies to divulge the actual quenching mechanism. From the thermodynamic observations, it is clear that the binding process is a spontaneous molecular interaction, in which van der Waals and hydrogen bonding interactions play the major roles. The UV–vis absorption and CD results confirm that the dye can induce conformational and micro-environmental changes of both the proteins. In addition, the dye binding provokes the functionality of the native proteins in terms of esterase-like activity. The average binding distance (<i>r</i>) between proteins and dye has been calculated using FRET. Cytotoxicity and antiviral effects of the dye have been found using Vero cell and <b>HSV-1F</b> virus by performing MTT assay. The AutoDock-based docking simulation reveals the probable binding location of dye within the sub-domain IIA of HSA and IB of BSA.</p

Gold nanorod embedded reduction responsive block copolymer micelle-triggered drug delivery combined with photothermal ablation for targeted cancer therapy

Background: Gold nanorods, by virtue of surface plasmon resonance, convert incident light energy (NIR) into heat energy which induces hyperthermia. We designed unique, multifunctional, gold nanorod embedded block copolymer micelle loaded with GW627368X for targeted drug delivery and photothermal therapy. Methods: Glutathione responsive diblock co-polymer was synthesized by RAFT process forming self-assembled micelle on gold nanorods prepared by seed mediated method and GW627368X was loaded on to the reduction responsive gold nanorod embedded micelle. Photothermal therapy was administered using cwNIR laser (808 nm; 4 W/cm²). Efficacy of nanoformulated GW627368X, photothermal therapy and combination of both were evaluated in vitro and in vivo. Results: In response to photothermal treatment, cells undergo regulated, patterned cell death by necroptosis. Combining GW627368X with photothermal treatment using single nanoparticle enhanced therapeutic outcome. In addition, these nanoparticles are effective X-ray CT contrast agents, thus, can help in monitoring treatment. Conclusion: Reduction responsive nanorod embedded micelle containing folic acid and lipoic acid when treated on cervical cancer cells or tumour bearing mice, aggregate in and around cancer cells. Due to high glutathione concentration, micelles degrade releasing drug which binds surface receptors inducing apoptosis. When incident with 808 nm cwNIR lasers, gold nanorods bring about photothermal effect leading to hyperthermic cell death by necroptosis. Combination of the two modalities enhances therapeutic efficacy by inducing both forms of cell death. General significance: Our proposed treatment strategy achieves photothermal therapy and targeted drug delivery simultaneously. It can prove useful in overcoming general toxicities associated with chemotherapeutics and intrinsic/acquired resistance to chemo and radiotherapy. Graphical abstract: Glutathione responsive diblock copolymer containing folic acid and lipoic acid forms self-assembled micelle around gold nanorods (AuNRs). GW627368X loaded AuNR embedded block copolymer micelles served dual purpose of targeted drug delivery and an effective photothermal agent. On reaching tumour vicinity, GSH triggered disassembly of micelles takes place releasing the drug which then binds EP4 receptors bringing about downstream effects. AuNRs start accumulating in and around the tumour/cancerous cells rendering it susceptible to hyperthermal demise. On irradiation with 808 nm NIR lasers, light energy is efficiently converted into heat energy owing to surface plasmon resonance of AuNRs leading to hyperthermal cell death

EPR interpretation, magnetism and biological study of a Cu(II) dinuclear complex assisted by a schiff base precursor

A new Cu(II) dinuclear complex, Cu2L2 (1) was afforded employing the potentially pentatentate Schiff base precursor H2L, a refluxed product of o-vanillin and diethylenetriamine in methanol. Complex 1 was systematically characterized by FTIR, UV-Vis, emission and EPR spectrometry. The single crystal X-ray diffraction analysis of 1 reveals that the copper atom exhibits a distorted square planar geometry, comprising two pairs of phenolato-O and imine-N donors from two different H2L ligands. The temperature dependent magnetic interpretation agrees with the existence of weak antiferromagnetic interactions between the bridging dinuclear Cu(II) ions. A considerable body of experimental evidence has been accumulated to elucidate the magneto-structural relationship in this dinuclear Cu(II) complex by DFT computation. Both the ligand and complex 1 exhibit anti-mycobacterial activity and considerable efficacy on M. tuberculosis H37Ra (ATCC 25177) and M. tuberculosis H(37)Rv (ATCC 25618) strains. The practical applicability of the ligand and complex 1 has been examined in living cells (African Monkey Vero Cells). The MTT assay proves the non-toxicity of the probe up to 100 mg mL(-1). A new homometallic dinuclear Cu(II) complex is afforded with a tetradentate Schiff base precursor. EPR interpretation and temperature dependent magnetic studies show that complex 1 has weak antiferromagnetic coupling and DFT computation is governed to explain the magneto-structural correlation