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Magnetic analogue of an isolated free electric charge, i.e., a magnet with a single north or south pole, is a long sought-after particle which remains elusive so far. In magnetically frustrated pyrochlore solids, a classical analogue of monopole was observed as a result of excitation of spin ice vertices. Direct visualization of such excitations were proposed and later confirmed in analogous artificial spin ice (ASI) systems of square as well as Kagome geometries. However, such magnetically charged vertices are randomly created as they are thermally driven and are always associated with corresponding equal and opposite emergent charges, often termed as monopole–antimonopole pairs, connected by observable strings. Here, we demonstrate a controlled stabilisation of a robust isolated emergent monopole-like magnetically charged vertices in individual square ASI systems by application of an external magnetic field. The excitation conserves the magnetic charge without the involvement of a corresponding excitation of opposite charge. Well supported by Monte Carlo simulations our experimental results enable, in absence of a true elemental magnetic monopole, creation of electron vortices and studying electrodynamics in presence of a monopole-like field in a solid state environment.

Gold nanocages (AuNcgs) are well-studied, hollow, metallic nanostructures that have fascinated researchers in the fields of nanotechnology, materials science, photoelectronics, biotechnology, and medical science for the last decade. However, the time-consuming synthesis of AuNcgs has limited their widespread use in materials science and nano-biotechnology. A novel, ultra-fast, simple, and highly convenient method for the production of AuNcgs using microwave heating is demonstrated herein. This quick method of AuNcg synthesis requires mild laboratory conditions for large-scale production of AuNcgs. The microwave heating technique offers the advantage of precise mechanical control over the temperature and heating power, even for the shortest reaction period (i.e., seconds). Microwave-synthesized AuNcgs were compared with conventionally synthesized AuNcgs. Structural maneuver studies employing the conventionally produced AuNcgs revealed the formation of screw dislocations and a shift in the lattice plane. Detailed characterization of the microwave-generated AuNcgs was performed using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and spectroscopic techniques.

Nanoarchitectures of titania (TiO2) have been widely investigated for a number of medical applications including implants and drug delivery. Although titania is extensively used in the food, drug and cosmetic industries, biocompatibility of nanoscale titania is still under careful scrutiny due to the conflicting reports on its interaction with cellular matter. For an accurate insight, we performed in vitro studies on the response of human dermal fibroblast cells toward pristine titania nanotubes fabricated by anodic oxidation. The nanotubes at low concentrations were seen to induce toxicity to the cells, whereas at higher concentrations the cell vitality remained on par with controls. Further investigations revealed an increase in the G0 phase cell population depicting that majority of cells were in the resting rather than active phase. Though the mitochondrial set-up did not exhibit any signs of stress, significantly enhanced reactive oxygen species production in the nuclear compartment was noted. The TiO2 nanotubes were believed to have gained access to the nuclear machinery and caused increased stress leading to genotoxicity. This interesting property of the nanotubes could be utilized to kill cancer cells, especially if the nanotubes are functionalized for a specific target, thus eliminating the need for any chemotherapeutic agents.

Alzheimer’s disease is becoming a serious concern in the medical field due to its severity and prevalence. This multifactorial disease manifested by various genetic and nongenetic factors makes its treatment very difficult. Due to the inefficacy of the currently available drugs, newer therapeutic strategies are increasingly in demand. Most of the current drug discovery initiatives are pivoted around amyloid pathology which is considered to be central to the disease progression. In this work, we propose the use of amyloid-binding aptamer conjugated to poly(lactic-co-glycolic acid) (PLGA)-coated curcumin nanoparticles to bind to the amyloid plaques. Curcumin is a plant-derived compound with reported anti-amyloid activity. Recent reports reveal the importance of plasma amyloid in Alzheimer development. We propose that the amyloid-binding aptamer attached curcumin–PLGA nanoparticles can be used as a potential tool in targeting the plasma amyloid and thus helps in Alzheimer therapy.

Target-specific drug delivery system that can transport an effective dosage of anti-cancer drugs to the targeted tumor cells can significantly reduce drug toxicity to the normal cells and increase the therapeutic effect of the drug. In our work, we have evaluated the cytotoxic potential of paclitaxel-loaded silica nanoparticles (Si-PTX NPs) prepared by template-directed stober synthesis technique. The particles were characterized using transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. We have modified the surface of the drug-loaded particles chemically and conjugated a tumor-specific aptamer (Apt-Si-PTX NPs) to facilitate targeted drug delivery to the cancer cells. In vitro studies carried out demonstrated that the aptamer-conjugated paclitaxel-loaded silica nanoparticles could target the cancer cells with high specificity and destroy them effectively, while sparing the normal cells. This work concludes that the aptamer-tagged paclitaxel-loaded silica nanoparticles are excellent targeting moieties for targeted drug delivery to tumor cells.

The use of fluorescent nanomaterials has gained great importance in the field of medical imaging. Many traditional imaging technologies have been reported utilizing dyes in the past. These methods face drawbacks due to non-specific accumulation and photobleaching of dyes. We studied the uptake and internalization of two different sized (30 nm and 100 nm) FITC labeled silica nanoparticles in Human umbilical vein endothelial cell line. These nanomaterials show high biocompatability and are highly photostable inside live cells for increased period of time in comparison to the dye alone. To our knowledge, we report for the first time the use of 30 nm fluorescent silica nanoparticles as efficient endothelial tags along with the well studied 100 nm particles. We also have emphasized the good photostability of these materials in live cells.

Zinc aluminate nanoparticles with average particle size of 40 nm were synthesized using a sol–gel combustion method. X-ray diffractometry result was analysed by Rietveld refinement method to establish the phase purity of the material. Different stages of phase formation of the material during the synthesis were investigated using differential scanning calorimetry and differential thermogravimetric analysis. Particle size was determined with transmission electron microscopy and the optical bandgap of the nanoparticles was determined by absorption spectroscopy in the ultraviolet-visible range. Dielectric permittivity and a.c. conductivity of the material were measured for frequencies from 100 kHz to 8 MHz in the temperature range of 30–120°C. The presence of Maxwell–Wagner type interfacial polarization was found to exist in the material and hopping of electron by means of quantum mechanical tunneling is attributed as the reason for the observed a.c. conductivity.

The magnetocaloric properties of cobalt ferrite nanoparticles were investigated to evaluate the potential of these materials as magnetic refrigerants. Nanosized cobalt ferrites were synthesized by the method of sol–gel combustion. The nanoparticles were found to be spherical with an average crystallite size of 14 nm. The magnetic entropy change (ΔSm) calculated indirectly from magnetization isotherms in the temperature region 170–320 K was found to be negative, signifying an inverse magnetocaloric effect in the nanoparticles. The magnitudes of the ΔSm values were found to be larger when compared to the reported values in the literature for the corresponding ferrite materials in the nanoregime.

Nano magnetic oxides are promising candidates for high density magnetic storage and other applications. Nonspherical mesoscopic iron oxide particles are also candidate materials for studying the shape, size and strain induced modifications of various physical properties viz. optical, magnetic and structural. Spherical and nonspherical iron oxides having an aspect ratio, ∼2, are synthesized by employing starch and ethylene glycol and starch and water, respectively by a novel technique. Their optical, structural, thermal and magnetic properties are evaluated. A red shift of 0·24 eV is observed in the case of nonspherical particles when compared to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the elongated iron oxide particles. Pressure induced effects are due to the increased overlap of wave functions. Magnetic measurements reveal that particles are superparamagnetic. The marked increase in coercivity in the case of elongated particles is a clear evidence for shape induced anisotropy. The decreased specific saturation magnetization of the samples is explained on the basis of weight percentage of starch, a nonmagnetic component and is verified by TGA and FTIR studies. This technique can be modified for tailoring the aspect ratio and these particles are promising candidates for drug delivery and contrast enhancement agents in magnetic resonance imaging.

Curcin, a type 1 ribosome inactivating protein (RIP) is investigated here for its cellular competence on six mammalian cell lines. Cells exposed to curcin (100 μg/ml) for 72 h exhibited significant cellular metabolic arrest, with the cancer cell lines being more sensitive. The viability assessment of the cancer cells in a 3D cell culture based assay revealed highly restricted sprouting and proliferation with near to complete dead cell population. Prominent mitochondrial dysfunction, elevated reactive oxygen species levels, nuclear degeneration, structural/mechanical destabilization and suppression of defense mechanisms were imminent with the RIP treated cells. Expression levels of nuclear factor κB (NF-κB), cytoskeletal focal adhesion kinases (FAK) and vinculin were significantly diminished. Vital cellular organelles as nucleus, mitochondria and actin were severely incapacitated on RIP exposure resulting in multimodal apoptosis and necrosis. The ability of curcin to impart comprehensive shutdown of the cells, especially cancer cells, complemented with its hemocompatibility, opens up possibilities of utilizing this ribotoxin as a prospective therapeutic candidate against cancers of diverse origins.

Dark conduction in radio frequency plasma polymerized Furan thin film is reported. A contact limited Schottky mechanism is found to predominate. A comparison of the value from different experimental studies and the value from theoretical studies confirm the Schottky type mechanism in Furan thin film.

Nanocrystals (NCs) with anisotropic dimensions display polarized emission compared to nano dots. Triangular prisms are good candidates for polarized optical properties and monodisperse trian- gular NCs are ideal for developing building blocks for novel three-dimensional superlattices due to its aniso- tropic dimension. Among triangular nanocrystals, CdS nanocrystals are less discussed for the past one decade of research due to the difficulty in its processing method. Though well studied very few methods for developing CdS triangular nanocrystals have been reported, and most are having drawbacks either due to the time consuming process or the products are combination of triangular as well as many other shaped NC or with trap emissions due to defects which are comparable to band emissions limits its applica- tions in full scale. Here, we are presenting a novel method to develop 7 nm CdS triangular NCs that can solve the above mentioned problems, which would augment the usage of CdS triangular crystals for many applications, based on its anisotropic properties.