Gargi Mishra

PEGylated Carbon Nanocapsule: A Universal Reactor and Carrier for In Vivo Delivery of Hydrophobic and Hydrophilic Nanoparticles

We have developed PEGylated mesoporous carbon nanocapsule as a universal nanoreactor and carrier for the delivery of highly crystalline hydrophobic/hydrophilic nanoparticles (NPs) which shows superior biocompatibility, dispersion in body fluids, good biodistribution and NPs independent cellular uptake mechanism. The hydrophobic/hydrophilic NPs without surface modification were synthesized in situ inside the cavities of mesoporous carbon capsules (200-850 nm). Stable and inert nature of carbon capsules in a wide range of reaction conditions like high temperature and harsh solvents, make it suitable for being used as nano/microreactors for the syntheses of a variety of NPs for bioimaging applications, such as NaYF4:Eu(3+)(5%), LaVO4:Eu(3+)(10%), GdVO4:Eu(3+)(10%), Y2O3:Eu(3+)(5%), GdF3:Tb(3+)(10%), Mo, Pt, Pd, Au, and Ag. Multiple types of NPs (Y2O3:Eu(3+)(5%) (hydrophobic) and GdF3:Tb(3+)(10%) (hydrophilic)) were coloaded inside the carbon capsules to create a multimodal agent for magneto-fluorescence imaging. Our in vivo study clearly suggests that carbon capsules have biodistribution in many organs including liver, heart, spleen, lungs, blood pool, and muscles.

Multifunctional Mesoporous Carbon Capsules and their Robust Coatings for Encapsulation of Actives: Antimicrobial and Anti-bioadhesion Functions

We present the synthesis and applications of multifunctional hollow porous carbon spheres with well-ordered pore architecture and ability to encapsulate functional nanoparticles. In the present work, the applications of hollow mesoporous carbon capsules (HMCCs) are illustrated in two different contexts. In the first approach, the hollow capsule core is used to encapsulate silver nanoparticles to impart antimicrobial characteristics. It is shown that silver-loaded HMCCs (concentration ∼100 μg/mL) inhibit the growth and multiplication of bacterial colonies of Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) up to 96% and 83%, respectively. In the second part, the fabrication of hierarchical micro- and nanostructured superhydrophobic coatings of HMCCs (without encapsulation with silver nanoparticles) is evaluated for anti-bioadhesion properties. Studies of protein adsorption and microorganism and platelet adhesion have shown a significant reduction (up to 100%) for the HMCC-based superhydrophobic surfaces compared with the control surfaces. Therefore, this unique architecture of HMCCs and their coatings with the ability to encapsulate functional materials make them a promising candidate for a variety of applications.

Direct Intranuclear Anticancer Drug Delivery via Polydimethylsiloxane Nanoparticles: in Vitro and in Vivo Xenograft Studies

Direct delivery of anticancer drugs to nuclei of tumor cells is required to enhance the therapeutic activity, which can be achieved by a nuclear localization signal (NLS) or peptide-decorated nanovehicles. However, NLS/peptide-based approaches may create certain undesirable immunological responses and the utilized synthesis processes are generally labor intensive. To this end, we report ligand-free, enhanced intranuclear delivery of Doxorubicin (Dox) to different cancer cells via porous polydimethylsiloxane (PDMS) nanoparticles (NPs). PDMS NPs were prepared by sacrificial silica template-based approach and Dox was loaded into the pores of PDMS NPs. These Dox-loaded PDMS NPs show enhanced cytotoxicity and reduce the IC50 values by 84 and 54% for HeLa and PC-3, respectively, compared to free Dox. Further, DNA damage in HeLa cells was estimated using comet assay suggesting enhanced DNA damage (72%) with Dox-loaded PDMS NPs as compared to free Dox (12%). The therapeutic efficiency of PDMS-Dox drug delivery system was tested in prostate cancer (PC-3) xenografts in NOD/SCID mice which showed enhanced tumor reduction (∼66%) as compared to free Dox. Taken together, our PDMS-Dox delivery system shows efficient and enhanced transportation of Dox to tumor cells which can be harnessed to develop advanced chemotherapy-based approaches to treat prostate and other cancers.

A polyaniline wrapped aminated graphene composite on nickel foam as three-dimensional electrodes for enzymatic microfuel cells

Three dimensional flow-through electrodes made of Ni foam coated with aminated graphene and polyaniline composites are studied for enzymatic glucose based microfuel cells. The composites of aminated graphene and polyaniline were prepared by in situ aniline polymerization with aminated graphene in different ratios. The prepared composites were characterized using XRD, FTIR and SEM. Pristine aminated graphene, polyaniline and various ratios of both were dip-coated on Ni foam and tested as a three-dimensional electrode in enzymatic microfuel cells. The enzyme was physically adsorbed and covalently bonded using a cross-linker on the electrode surface and in some cases; the electrode surface was functionalized before covalent attachment of enzyme and tested for an anode half-cell. The electrochemical studies demonstrated that the composite performed better than the pristine and was more promising when it was functionalized and enzymes where covalently bonded to the electrode surface. The maximum power density was observed as 118 μW cm−2 for the composite.

Poisson effect driven anomalous lattice expansion in metal nanoshells

Surface stress can have profound effects on nanoscale materials and can lead to a contraction of the lattice in nanoparticles to compensate for the under-coordination of the surface atoms. The effect of elastic properties like Poissons ratio can be accentuated in lower dimensional systems. The current study focuses on hollow metal nanoshells (MNSs), wherein there is interplay between the surface stresses existing in the inner and outer surfaces. Using a two scale computational method and transmission electron microscopy, we not only show a lattice expansion (in the radial direction) due to purely surface stress effects in a metallic system but also discover anomalous lattice expansion in the case of very thin walled MNSs. We argue that this effect, wherein the stress in the outer surface causes expansion in the radial lattice parameter (instead of compression), is a Poisson effect driven phenomenon. Although Ni nanoshells are used as an illustrative system for the studies, we generalize this effect for a...