Adhimoorthy Prasannan

Formation of gold decorated porphyrin nanoparticles and evaluation of their photothermal and photodynamic activity.

A core-shell gold (Au) nanoparticle with improved photosensitization have been successfully fabricated using Au nanoparticles and 5,10,15,20 tetrakis pentafluorophenyl)-21H,23H-porphine (PF6) dye, forming a dyad through molecular self-assembly. Au nanoparticles were decorated on the shell and PF6 was placed in the core of the nanoparticles. Highly stable Au nanoparticles were achieved using PF6 with poly(N-vinylcaprolactam-co-N-vinylimidazole)-g-poly(D,L-lactide) graft copolymer hybridization. This was compared with hybridization using cetyltrimethylammonium bromide and polyethylene glycol-b-poly(D,L-lactide) for shell formation with PF6-Au. The resulting PF6-poly(N-vinylcaprolactam-co-N-vinylimidazole)-g-poly(D,L-lactide)-Au core-shell nanoparticle were utilized for photothermal and photodynamic activities. The spectroscopic analysis and zeta potential values of micelles revealed the presence of a thin Au layer coated on the PF6 nanoparticle surface, which generally enhanced the thermal stability of the gold nanoparticles and the photothermal effect of the shell. The core-shell PF6-Au nanoparticles were avidly taken up by cells and demonstrated cellular phototoxicity upon irradiation with 300W halogen lamps. The structural arrangement of PF6 dyes in the core-shell particles assures the effectiveness of singlet oxygen production. The study verifies that PF6 particles when companied with Au nanoparticles as PF6-Au have possible combinational applications in photodynamic and photothermal therapies for cancer cells because of their high production of singlet oxygen and heat.

Effect of aromatic and aliphatic amines as curing agents in sulfone epoxy monomer curing process

The kinetics of the curing of sulfone epoxy (SEP) monomers using aromatic and aliphatic amine curing agents was studied via differential scanning calorimetry (DSC). SEP curing is a two-stage process involving SEP/electron donation and electron donation to either aliphatic or aromatic curing agents. The SEP/electron donation curing process occurred readily since semi-electron-withdrawing curing agents are induced by nucleophilic substitution in the first stage. In the second stage, SEP is cured by the semi-electron-withdrawing curing agents. The kinetic parameters of the curing process were determined using a conversional method derived from Ozawa’s and Kissinger’s methods, which are typically used for kinetic analysis of data for thermal treatments. The higher melting points and steric bulk of the aromatic curing agents resulted in higher curing activation energies than for the aliphatic curing agents. The aliphatic curing agents also increased the activation energy of the curing process due to their electron-withdrawing and cross-linking properties as well as the viscosity of the epoxy/amine curing system. Cured SEP/aromatic curing agent materials possessed higher glass transition temperatures than cured SEP/aliphatic curing agent materials.

Synthesis and evaluation of the targeted binding of RGD-containing PEGylated-PEI/DNA polyplex micelles as radiotracers for a tumor-targeting imaging probe

Site-specific labeling of molecular imaging probes necessitates the topical administration of medications during the development of homogeneous tracers. Hence, receptor-mediated gene transfer is believed to be of enormous significance in the clinical translation of a promising gene delivery technique. Plasmid DNA (pEGFP) and polycations produce polyplexes, which can be proficient probes for molecular imaging when accompanied by a gamma emitter. Therefore, this study describes the physico-biological characterization of a radiotracer for tumor imaging in a HeLa tumor-bearing mouse model. Polyplex micelles were formed with pEGFP and Arg-Gly-Asp (RGD) peptide-modified poly(ethylene glycol)-grafted polyethylenimine (E[c(RGDyK)]2-PEG-g-PEI) and were labeled with 99mTc for the in vivo study. The various PEG-g-PEIs prepared by controlling the PEG-to-PEI ratios were confirmed by 1H-NMR. The sizes and zeta potentials of the PEG-g-PEI/DNA polyplexes were 90–135 nm and 40–50 mV, respectively. The biophysical characterization of pEGFP in polyplexes was evaluated via various methods, including determination of the condensation efficiency of the polymers and the biodistribution, in vitro stability, in vivo application, and kinetics of the radiolabeled polyplexes. These characteristics were studied as a function of time using 3D-SPECT/CT images and by end-point scintillation counting. The polyplex of PEG-g-PEI/DNA fabricated with a PEG/PEI ratio of 10 : 1 and N/P = 1, i.e., PP10/D, exhibited the lowest cytotoxicity and the highest transfection efficiency. The cyclic-RGD peptide-modified polyplex PEG-g-PEI/DNA (RPP10/D) had significantly higher binding affinity and transfection efficiency than the non-targeting PP10/D did. 99mTc radio-labeled PP10/D and RPP10/D were prepared with high radiolabeling efficiency of greater than 95% and radiochemical stability above 80%, both in saline and in rat plasma, when stored for 24 h and were evaluated for their tumor-targeting capability and biodistribution. Through in vivo SPECT/CT images, it was determined that RPP10/D-99mTc presented higher uptake in the tumor than PP10/D-99mTc at all of the post-injection times studied. We found that the two tracers of radioactive complexes mainly accumulated in the liver, spleen and kidneys at 24 h after intravenous injection in female BALB/c nude mice bearing subcutaneous HeLa tumors. The accumulation of the site-specifically labeled RPP10/D-99mTc was lower in liver, kidney and spleen compared with non-targeting PP10/D-99mTc.

Natural Biowaste-Cocoon-Derived Granular Activated Carbon-Coated ZnO Nanorods: A Simple Route To Synthesizing a Core–Shell Structure and Its Highly Enhanced UV and Hydrogen Sensing Properties

Granular activated carbon (GAC) materials were prepared via simple gas activation of silkworm cocoons and were coated on ZnO nanorods (ZNRs) by the facile hydrothermal method. The present combination of GAC and ZNRs shows a core-shell structure (where the GAC is coated on the surface of ZNRs) and is exposed by systematic material analysis. The as-prepared samples were then fabricated as dual-functional sensors and, most fascinatingly, the as-fabricated core-shell structure exhibits better UV and H2 sensing properties than those of as-fabricated ZNRs and GAC. Thus, the present core-shell structure-based H2 sensor exhibits fast responses of 11% (10 ppm) and 23.2% (200 ppm) with ultrafast response and recovery. However, the UV sensor offers an ultrahigh photoresponsivity of 57.9 A W-1, which is superior to that of as-grown ZNRs (0.6 A W-1). Besides this, switching photoresponse of GAC/ZNR core-shell structures exhibits a higher switching ratio (between dark and photocurrent) of 1585, with ultrafast response and recovery, than that of as-grown ZNRs (40). Because of the fast adsorption ability of GAC, it was observed that the finest distribution of GAC on ZNRs results in rapid electron transportation between the conduction bands of GAC and ZNRs while sensing H2 and UV. Furthermore, the present core-shell structure-based UV and H2 sensors also well-retained excellent sensitivity, repeatability, and long-term stability. Thus, the salient feature of this combination is that it provides a dual-functional sensor with biowaste cocoon and ZnO, which is ecological and inexpensive.

Evaluation of the bacterial anti-adhesive properties of polyacrylic acid, chitosan and heparin-modified medical grade Silicone rubber substrate

In this study, we aimed to develop polyelectrolyte multilayered films that could be absorbed onto a silicone rubber substrate; this composite material was then tested for its ability to inhibit bacterial adhesion. Polyacrylic acid (PAA) grafting onto the silicone rubber substrate was confirmed by attenuated total reflectance-infrared spectroscopy and the surface roughness of multilayered films was measured using an atomic force microscope and scanning electron microscopy. Immobilization of PAA, chitosan (CS) and heparin (HEP) films conferred antibacterial activity against Escherichia coli and Staphylococcus Aureus. The adhesion of both E. coli and S. aureus on PAA-CS-HEP multilayer film was reduced when compared to pristine, PAA, and PAA–CS films; this was due to effective complex formation between polyelectrolytes and cell adhesion proteins. Moreover, immobilization of HEP on the PAA-CS composite was efficiently reduced cell adhesion.

Nucleation effects of α-cyclodextrin inclusion complexes on the crystallization behavior of biodegradable poly(1,4-butylene adipate)

This study examined the polymorphic crystallization behavior of poly(1,4-butylene adipate) (PBA) with the addition of nucleation agents such as the α-cyclodextrin (α-CD) inclusion complex (IC) of PBA (PBAIC) and the IC of poly(e-caprolactone) (PCLIC). The formation of PBAIC and PCLIC was characterized by 1H NMR, Fourier-transform infrared (FT-IR) spectroscopy and wide-angle X-ray diffraction (WAXD). The differential scanning calorimetry (DSC) and WAXD results suggest that some of the PBA segments remained outside the α-CD cavities even after the formation of ICs with α-CD. WAXD investigation also confirmed that the ICs had a channel structure. The DSC and polarized optical microscopy (POM) results showed the ICs to exhibit nucleation effects on the crystallization and polymorphic behavior of the PBA. The cooling rate played a significant role in the polymorphic crystallization behavior of the pure PBA. Thus, when the cooling rate was decreased, the crystal structures changed from β to α-form and vice versa. The blending of a nucleating agent with the PBA led to higher crystallization temperatures, thus favoring the nucleation of the α-form crystal of PBA rather than pure PBA. The nucleating activity of the PCLIC during the crystallization of the PBA was higher than that of PBAIC.

Facile synthesis of the structural hierarchy in chrysanthemum–snowball-like self-organized polyaniline

A facile synthesis of the “chrysanthemum–snowball”-shaped polyaniline (PAni) has been prepared by using self-assembly polymerization of the host–guest monomeric inclusion complex of β-cyclodextrin (β-CD) with aniline. The amount of the monomer complex plays a role as a structural regulator during fabrication of the inclusion polymer as chrysanthemum–snowball structure/nanorods via intermolecular interactions such as: hydrogen bonding between β-CD and PAni, π–π interactions and cooperative interaction between PAni with FeCl3 in an aqueous medium. The microstructure and morphology of the resulting materials were investigated by using various analytical techniques such as Fourier transform infrared, wide-angle X-ray diffraction, small-angle X-ray scattering, field emission scanning electron microscopy and transmission electron microscopy. After observing the growth process, a tentative mechanism is proposed to elucidate the formation of the PAni hierarchical structures.

Silk-sericin degummed wastewater solution-derived and nitrogen enriched porous carbon nanosheets for robust biological imaging of stem cells

Appreciated raw materials like silk-sericin can be recovered from silk-textile industrial waste for the production of novel functional nanomaterials. In this study, highly fluorescent sericin based carbon nanosheets (SCN) were produced from industrial wastewater containing silk-sericin as a precursor, and was applied as bio-imaging application for oral fat stem cells. A simple one-pot, hydrothermal carbonization method was used to produce SCN at a 180°C. The obtained hydrothermal carbons exhibited strong fluorescence properties due to the presence of strong polar groups, such as carboxyl, amino and amide groups in the surface. Heteroatom functionalization of the SCN leads to the property of fluorescence due to enriched nitrogen and was confirmed by X-ray photoelectron and Fourier transform infrared spectroscopy. The plate-like morphology of SCN about 35nm in size was evaluated by transmission electron microscopy. The carbon 13 nuclear magnetic resonance results revealed that nano-sized fluorescent SCN formed during carbonization and functionalization occurred through dehydration of the sericin protein. Moreover, the prepared SCNs demonstrated low toxicity and their suitability for bio-imaging applications was demonstrated to the oral fat stem cells. Overall, sericin degumming wastewater from the silk textile industry can be utilized for the production of SCNs for stem cells bio-imaging applications.

Fabrication of self-assembled vesicle nanoparticles of poly(l-lysine)–arachidic acid conjugates for a vascular endothelial growth factor carrier

Numerous growth factors account for tissue and organ development and therapeutic efficiency. Hence, the delivery of growth factors is crucial in regenerative medical practice. However, the delivery of a single factor to regenerate tissues lacks clinical utility in many current approaches. We reported the delivery of the bioactive vascular endothelial growth factor (VEGF) from novel polymeric vesicles. Polymeric vesicles were prepared from the poly(l-lysine)-g-polylysine(AA) amphiphilic graft copolymer through the conjugation of arachidic acid (AA) with poly(l-lysine) for obtaining a VEGF carrier. The prepared copolymer can form a polymersome and effectively condense with VEGF without affecting its size and surface charges. The Gaussian curve fit (GCF) of amide I band were revealed that VEGF efficiently interact through the α-helix of the amphiphilic graft copolymer rather than β-sheet dominated poly(l-lysine). The polymersome-VEGF complex showed a considerably higher binding affinity, transfection efficiency, and less toxicity because of the peptide-based polymer backbone. Compared with the poly(l-lysine)-VEGF complex, polymersome-VEGF revealed a high secretion of VEGF and low toxicity. These polymersomes can deliver angiogenic factors in a controlled manner in tissue regeneration and biomedical engineering.

Structural formation of inclusion complex nanoparticles from α–cyclodextrin and polysebacic acid

Inclusion complexes (IC) of α–cyclodextrin (α–CD) and biodegradable polysebacic acid (PSA) are prepared by using two different conditions of pH values. Interestingly, IC prepared at neutral pH (pH 7) shows turbidity and then into white precipitate, while IC prepared at alkaline pH (pH 10) forms into a clear solution, indicating the pH dependent behaviour of the IC and its formation of supramolecular assembly varies significantly by changing the pH. Moreover, it is found that by changing the pH, the affinity of the guest molecules with the CD cavity differs from strong intermolecular hydrogen bonding to weakly electrostatic interaction between PSA and α–CD. All experimental results suggest that the PSA chains are included into the α–CD cavity and the nanostructure of IC possesses a channel structure. PSA self–assembled into nanostructures in alkaline solution upon the addition of α–CD. The nanostructures produced were vesicular in shape as observed by TEM and hydrodynamic radius (Rh) obtained from DLS was ca.128 nm.