Microwave-Induced Chemotoxicity of Polydopamine-Coated Magnetic Nanocubes

Polydopamine-coated FeCo nanocubes (PDFCs) were successfully synthesized and tested under microwave irradiation of 2.45 GHz frequency and 0.86 W/cm2 power. These particles were found to be non-toxic in the absence of irradiation, but gained significant toxicity upon irradiation. Interestingly, no increase in relative heating rate was observed when the PDFCs were irradiated in solution, eliminating nanoparticle (NP)-induced thermal ablation as the source of toxicity. Based on these studies, we propose that microwave-induced redox processes generate the observed toxicity

Non-Resonant Large Format Surface Enhanced Raman Scattering Substrates for Selective Detection and Quantification of Xylene Isomers

Non-Resonant Large Format Surface Enhanced Raman Scattering Substrates for Selective Detection and Quantification of Xylene Isomer

Magnetotactic bacterial cages as safe and smart gene delivery vehicles

In spite of the huge advances in the area of synthetic carriers, their efficiency still poorly compares to natural vectors. Herein, we report the use of unmodified magnetotactic bacteria as a guidable delivery vehicle for DNA functionalized gold nanoparticles (AuNPs). High cargo loading is established under anaerobic conditions (bacteria is alive) through endocytosis where AuNPs are employed as transmembrane proteins mimics (facilitate endocytosis) as well as imaging agents to verify and quantify loading and release. The naturally bio-mineralized magnetosomes, within the bacteria, induce heat generation inside bacteria through magnetic hyperthermia. Most importantly after exposing the system to air (bacteria is dead) the cell wall stays intact providing an efficient bacterial vessel. Upon incubation with THP-1 cells, the magnetotactic bacterial cages (MBCs) adhere to the cell wall and are directly engulfed through the phagocytic activity of these cells. Applying magnetic hyperthermia leads to the dissociation of the bacterial microcarrier and eventual release of cargo

pH Responsive Self-Assembly of Cucurbit[7]urils and Polystyrene-Block-Polyvinylpyridine Micelles for Hydrophobic Drug Delivery

Polystyrene-block-polyvinylpyridine (PS-b-P4VP) polypseudorotaxanes with cucurbit[7]urils (CB[7]) were prepared from water soluble PS-b-P4VPH+ polymer and CB[7] in aqueous solution at room temperature. At acidic and neutral pH, the pyridinium block of PS-b-P4VP is protonated (PS-b-P4VPH+) pushing CB[7] to preferably host the P4VP block. At basic pH (pH 8), P4VP is not charged and thus is not able to strongly complex CB[7]. This phenomenon was verified further by monitoring the release of pyrene, a hydrophobic cargo model, from a PS-b-P4VPH+/CB[7] micellar membrane. Release study of UV active pyrene from the membrane at different pH values revealed that the system is only operational under basic conditions and that the host-guest interaction of CB[7] with P4VPH+ significantly slows down cargo release

Experimental and theoretical evaluation of nanodiamonds as pH triggered drug carriers

Nanodiamond (ND) and its derivatives have been widely used for drug, protein and gene delivery. Herein, experimental and theoretical methods have been combined to investigate the effect of pH on the delivery of doxorubicin (DOX) from fluorescein labeled NDs (Fc-NDs). In the endosomal recycling process, the nanoparticle will pass from mildly acidic vesicle to pH approximate to 4.8; thus, it is important to investigate DOX release from NDs at different pH values. Fc-NDs released DOX dramatically under acidic conditions, while an increase in the DOX loading efficiency (up to 6.4 wt%) was observed under basic conditions. Further theoretical calculations suggest that H+ weakens the electrostatistic interaction between ND surface carboxyl groups and DOX amino groups, and the interaction energies at pH 7 are 10.4 kcal mol(-1), 25.0 kcal mol(-1) and 27.0 kcal mol(-1) respectively. Cellular imaging experiments show that Fc-NDs are readily ingested by breast adenocarcinoma (BA) cells and cell viability tests prove that they can be utilized as a safe drug delivery vehicle. Furthermore, pH triggered DOX release has been tested in vitro (pH 7.4 and pH 4.83) in breast adenocarcinoma (BA) cells

Investigating Unexpected Magnetism of Mesoporous Silica-Supported Pd and PdO Nanoparticles

The synthesis and magnetic behavior of matrix-supported Pd and PdO nanoparticles (NPs) are described. Mesoporous silica with hexagonal columnal packing is selected as a template, and the impregnation method with thermal annealing is used to obtain supported Pd and PdO NPs. The heating rate and the annealing conditions determine the particle size and the phase of the NPs, with a fast heating rate of 30 °C/min producing the largest supported Pd NPs. Unusual magnetic behaviors are observed. (1) Contrary to the general belief that smaller Pd NPs or cluster size particles have higher magnetization, matrix-supported Pd NPs in this study maintain the highest magnetization with room temperature ferromagnetism when the size is the largest. (2) Twin boundaries along with stacking faults are more pronounced in these large Pd NPs and are believed to be the reason for this high magnetization. Similarly, supported PdO NPs were prepared under air conditions with different heating rates. Their phase is tetragonal (P4₂/mmc) with cell parameters of <i>a</i> = 3.050 Å and <i>c</i> = 5.344 Å, which are slightly larger than in the bulk phase (<i>a</i> = 3.03 Å, <i>c</i> = 5.33 Å). Faster heating rate of 30 °C/min also produces larger particles and larger magnetic hysteresis loop, although magnetization is smaller and few twin boundaries are observed compared to the supported metallic Pd NPs

Selective Magnetic Evolution of Mn_<i>x</i>Fe_1–<i>x</i>O Nanoplates

Iron–manganese oxide (Mn_<i>x</i>Fe_1–<i>x</i>O) nanoplates were prepared by the thermal decomposition method. Irregular development of crystalline phases was observed with the increase of annealing temperature. Magnetic properties are in accordance with their respective crystalline phases, and the selective magnetic evolution from their rich magnetism of Mn_<i>x</i>Fe_1–<i>x</i>O and MnFe₂O₄ is achieved by controlling the annealing conditions. Rock-salt structure of Mn_<i>x</i>Fe_1–<i>x</i>O (space group <i>Fm</i>3̅<i>m</i>) is observed in as-synthesized nanoplates, while MnFe₂O₄ and Mn_<i>x</i>Fe_1–<i>x</i>O with significant magnetic interactions between them are observed at 380 °C. In nanoplates annealed at 450 °C, soft ferrites of Mn_0.48Fe_2.52O₄ with Mn_<i>x</i>Fe_1–<i>x</i>O are observed. It is assumed that the differential and early development of crystalline phase of Mn_<i>x</i>Fe_1–<i>x</i>O and the inhomogeneous cation mixing between Mn and Fe cause this rather extraordinary magnetic development. In particular, the prone nature of divalent metal oxides to cation vacancy and the prolonged annealing time of 15 h which enables ordering are also thought to contribute to these irregularities

Histidine–dialkoxyanthracene dyad for selective and sensitive detection of mercury ions

<p>Histidine-dialkoxyanthracene (HDA) was synthesised as a turn off type fluorescent sensor for fast and sensitive detection of mercury ions (Hg²⁺) in aqueous media. The two histidine moieties act as ‘claws’ to selectively complex Hg²⁺. The binding ratio of HDA to Hg²⁺ was 1:1 (metal-to-ligand ratio). The association constant for Hg²⁺ towards the receptor HDA obtained from Benesi–Hildebrand plot was found to be 3.22 × 10⁴ M⁻¹ with detection limit as low as 4.7 nM (0.94 μg/L).</p