Influence of Luminol Doping of Poly(o-phenylenediamine) on the Spectral, Morphological, and Fluorescent properties: A Potential Fluorescent Marker for Early detection and Diagnosis of Leishmania donovani

Synthesis and characterization of pH-responsive conducting polymer/Na-alginate/gelatin based composite hydrogels for sustained release of amoxicillin drug

Composite hydrogels of Na-Alginate (Na-ALG) and Gelatin (GEL) with conducting polymers (CPs) were synthesised using poly(o-phenylenediamine) (POPD), polyaniline (PANI), poly(1-naphthylamine (PNA) and poly(vinylenedine fluoride) (PVDF). The synthesised hydrogels were characterized using FTIR, scanning electron microscopy (SEM) rheology, swelling ability and in-vitro drug release characteristics. The purpose of this investigation was to determine whether these hydrogels could be used to deliver antibiotics for extended drug release. The composite hydrogels were loaded with antibiotic drug: amoxicillin in three different concentrations and the release was studied at intestinal fluid (pH 7.4) and gastric fluid (pH 1.2). Release kinetics was found to show best fit in zero order models at both pH values and showed prolonged release characteristics. The POPD-Na-ALG/GEL showed highest release at intestinal pH of 7.4, while PVDF-Na-ALG/GEL showed highest release at gastric pH at 1.2.

Dye Modified Phenylenediamine Oligomers: Theoretical Studies on Drug Binding for Their Potential Application in Drug Sensors

The present work reports, for the first time, synthesis of dye incorporated o-phenylenediamine (OBB) with a view to obtain a conjugated oligomer with enhanced functionality. The structure was confirmed by IR studies, while the electronic transitions were confirmed by UV visible studies. The dye modified oligomer showed one order higher fluorescence intensity than the pristine Bismarck Brown (BB) dye. Confocal imaging showed red emission which could be utilized in near infra-red imaging. Density functional theory (DFT) studies were carried out to predict the theoretical properties of the oligomers. The energies of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital orbital were computed to explore how the HOMO energies of the reactants initiated the electronic interactions between them. The interaction energies were correlated to conjugation/hyper conjugation stabilization energies of the natural bond orbitals (NBO) via the DFT method using the B3LYP functional with the 6-311G(d) basis set on Gaussian 09 software. Drug binding was evaluated through simulation of interaction energy, (ΔEA-x) with drugs such as captopril, propranolol, thiazide, and fentanyl. The results predicted that the oligomer could be developed into a fentanyl drug sensor.

Theoretical Studies of Conducting Polymers: A Mini Review

The present short review discusses the computational studies carried out on polyacetylene (PAc), polyaniline (PANI), polypyrrole (PPy), and other conducting polymers for predicting their electronic, optoelectronic and structural properties. Studies...

Conducting polymers/zinc oxide-based photocatalysts for environmental remediation: a review

The accessibility to clean water is essential for humans, yet nearly 250 million people die yearly due to contamination by cholera, dysentery, arsenicosis, hepatitis A, polio, typhoid fever, schistosomiasis, malaria, and lead poisoning, according to the World Health Organization. Therefore, advanced materials and techniques are needed to remove contaminants. Here, we review nanohybrids combining conducting polymers and zinc oxide for the photocatalytic purification of waters, with focus on in situ polymerization, template synthesis, sol-gel method, and mixing of semiconductors. Advantages include less corrosion of zinc oxide, less charge recombination and more visible light absorption, up to 53%.

A new diagnostic strategy which uses a luminol-H2O2 system to detect helminth eggs in fecal sediments processed by the Helmintex method

Schistosomiasis remains a serious public health problem in tropical regions, affecting more than 250 million people. Sensitive diagnostic methods represent key tools for disease elimination, in particular in areas with low endemicity. Advances in the use of luminol-based chemiluminescent techniques have enabled greater sensitivity and speed in obtaining results in different diagnostic settings. In this study, we developed a luminol-H₂O₂ chemiluminescence (CL) method to detect Schistosoma mansoni eggs in human fecal sediments processed by the Helmintex (HTX) method. After S. mansoni eggs were incubated with a solution of luminol-H₂O₂ the light emission was detected and measured by spectrophotometry at 431 nm for 5 min, using detection and counts of eggs by bright field optical microscopy as a reference. CL intensity was found to correlate with different sources and numbers of eggs. Furthermore, our results showed that the CL method can distinguish positive from negative samples with 100% sensitivity and 71% specificity. To our knowledge, this is the first study to report the use of CL for the diagnosis of helminths from fecal samples. The combination of the HTX method with CL represents an important advance in providing a reference method with the highest standards of sensitivity.

Schistosomiasis, the infection caused by parasites of the genus Schistosoma, is still a significant health problem in many countries, despite some successful control efforts. In areas where parasite load is low and few eggs are released in feces, most diagnostic tests fail to detect the infections. Helmintex is a very sensitive, but time consuming, egg-detection method, with most time being consumed in observations of samples at the microscope. Here we report standardization of an innovative luminol-H₂O₂ chemiluminescence reaction triggered by Schistosoma mansoni eggs that may improve their detection in feces. Improved diagnostic tests are urgently required as part of the schistosomiasis elimination efforts.

Experimental and Theoretical Studies of Novel Azo Benzene Functionalized Conjugated Polymers: In-vitro Antileishmanial Activity and Bioimaging

To study the effect of insertion of azobenzene moiety on the spectral, morphological and fluorescence properties of conventional conducting polymers, the present work reports ultrasound-assisted polymerization of azobenzene with aniline, 1-naphthylamine, luminol and o-phenylenediamine. The chemical structure and polymerization was established via Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (1H-NMR) spectroscopy, while the electronic properties were explored via ultraviolet-visible (UV-vis) spectroscopy. Theoretical IR and UV spectra were computed using DFT/B3LYP method with 6-311G basis set while theoretical 1H-NMR spectra was obtained by gauge independent atomic orbital (GIAO) method. The theoretically computed spectra were found to be in close agreement with the experimental findings confirming the chemical as well as electronic structure of the synthesized polymers. Morphology was investigated by X-ray diffraction and transmission electron microscopy studies. Fluorescence studies revealed emission ranging between 530-570 nm. The polymers also revealed high singlet oxygen (1O2) generation characteristics. In-vitro antileishmanial efficacy as well as live cell imaging investigations reflected the potential application of these polymers in the treatment of leishmaniasis and its diagnosis.

Sensible graphene oxide differentiates macrophages and Leishmania: a bio-nano interplay in attenuating intracellular parasite

AGO-AmB nanocomposites as a potential therapeutic anti-leishmanial agents.

Development of a near infrared novel bioimaging agent via co-oligomerization of Congo red with aniline and o-phenylenediamine: experimental and theoretical studies

With a view to study the effect of insertion of a multifunctional dye moiety on the photo physical properties of conducting polymers, the present paper reports for the first time the homopolymerization and co-oligomerization of Congo red (CR) dye with aniline and o-phenylenediamine. The co-oligomerization was established by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹H-NMR), and ultraviolet-visible (UV-vis) spectroscopy while the morphology was examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The theoretical as well as experimental data of ¹H-NMR as well as IR studies confirmed the co-oligomer formation while ultraviolet-visible spectroscopy studies revealed a dynamic change in the optical properties upon variation of co-oligomer composition. X-ray diffraction studies established a crystalline morphology of oligomers. Live cell confocal imaging studies revealed that the co-oligomers could be effectively used in NIR imaging.

To study the effect of insertion of a multifunctional dye moiety on the photophysical properties of conducting polymers, the present paper reports for the first time the homopolymerization and co-oligomerization of Congo red (CR) dye with aniline and o-phenylenediamine.

Spectroscopic and Biophysical Interaction Studies of Water-soluble Dye modified poly(o-phenylenediamine) for its Potential Application in BSA Detection and Bioimaging

Ultrasound-assisted synthesis of water soluble poly(o-phenylenediamine) (POPD) and its doping with Acid Orange (AO), Fluorescein (Fluo) and Rhodamine-6G (R6G) dyes was carried out with a view to enhance the photophysical properties of POPD. XPS studies confirmed that doping of POPD occured through hydrogen bonding between NH group of POPD and C=O/SO-, S=O groups of the dyes. The presence of strong hydrogen bonding was also confirmed via UV-vis studies by the addition of urea and sodium chloride to the dye modified POPD adducts. Molar extinction coefficient of these adducts was found to bear a close relationship with the molecular structure. Fluorescence life time, (τf,) was found to be lowest (1.8 ns) for AO-POPD and highest (3.2 ns) for Fluo-POPD. The structure of AO-POPD was more strained, while that of Fluo-POPD was least strained. Intrinsic fluorescence decay constant, (k0f) showed increasing values for POPD, AO-POPD, Fluo-POPD, R6G-POPD as 0.071, 0.072, 0.153, and 0.172 (108 s-1), which could be correlated to the increasing strain-free molecular structure of the adducts. Circular dichroism spectra (CD) of BSA in presence of POPD and R6G- POPD revealed that it partially broke its helical structure, while Fluo-POPD and AO-POPD showed enhancement in the helical content. The 3-D fluorescence studies confirmed enhancement in hydrophobicity of POPD and R6G- POPD and increase in hydrophylicity of AO-POP and Fluo-POPD in the microenvironment of tryptophan residue-213 of BSA. Fluo-POPD and R6G-POPD adducts were chosen to find out the lowest detection limit (LOD) of BSA by differential pulse voltammetry (DPV) which was found to be 1.35 nM, and 1.65 nM using Fluo-POPD and R6G -POPD respectively. The binding constant of BSA with Fluo-POPD- and R6G-POPD was obtained as 3.98 × 106 Lmol-1 and 5.27 × 102 Lmol-1. These polymers could therefore, be used for the detection of BSA. Live cell imaging revealed that POPD nanoparticles were bound to the outer membrane of E. coli, while R6G-POPD, showed penetration into the cytoplasm and excellent labeling of E. coli. This facile technique could be used to design tunable biomarkers by tailoring the conjugated polymer with a desired dye molecule.

Microwave-assisted facile synthesis of poly(luminol-co-phenylenediamine) copolymers and their potential application in biomedical imaging

Conjugated copolymers have attracted much attention because of their outstanding photo-physical properties. The present work reports for the first time, microwave-assisted copolymerization of o-phenylenediamine with luminol using different weight ratios of the two monomers. The composition of the copolymers was confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (¹H-NMR) while monomer reactivity ratios were determined using the Fineman–Ross method. Ultraviolet-visible spectroscopy revealed the variation in polaronic states upon copolymerization while X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showed the morphology of the copolymers to be intermediate between that of the homopolymers. Confocal analysis and fluorescence studies revealed that the copolymers showed composition based blue as well as red emission which could be utilized for in vivo imaging of cancer cells.

Development of bioimaging agents based on poly(o-phenylendiamine and luminol).

Tuning the optical properties of poly(o-phenylenediamine-co-pyrrole) via template mediated copolymerization

Tailoring of conjugated monomers via copolymerization is a facile method to obtain tunable spectral, morphological and optical properties. To investigate the effect of copolymerization of pyrrole with o-phenylenediamine on the optoelectronic properties of the synthesized copolymers, the present work reports the synthesis of copolymers of o-phenylenediamine with pyrrole with varying mol ratios via chemical polymerization in methylene blue (MB) medium. Copolymerization was confirmed by Fourier transform infrared spectroscopy and ultraviolet-visible studies. Ultraviolet-visible spectroscopy revealed variation in the optical properties with the change in the monomer ratio. Fluorescence studies showed that the copolymer containing 80% poly(o-phenylenediamine) revealed highest quantum yield among all the copolymers. The emission color could therefore be tuned by careful selection of narrow band co-monomers, which could help in designing tunable fluorescence emitting materials for potential application in OLED devices.

Simultaneous near-infrared and green fluorescence from single conjugated polymer dots with aggregation-induced emission fluorogen for cell imaging

Highly fluorescent conjugated polymer dots with aggregation-induced emission fluorogen were applied in in vitro and in vivo cell imaging.