Nanostructured Gold Hollow Microspheres Prepared on Dissolvable Ceramic Hollow Sphere Templates

Gold nanoparticles decorated FOLFIRINOX loaded liposomes for synergistic therapy of pancreatic cancer

Pancreatic cancer is predicted to be the second highest cause of cancer deaths by 2030, with a mortality rate of 98 % and a 5-year survival rate of only 4-8 %. FOLFIRINOX which consists of four main ingredients has shown superior efficacy in treating patients with pancreatic cancer compared to other agents and combinations. However, toxicities have prevented full-dose use of FOLFIRINOX. In this study, we present the design of a liposome nanosystem that enables the sequential release of a drug combination that is called FOLFIRINOX using lipid-based nanosystem synergistic chemo/photothermal therapy approaches. The co-eccentric liposome allowed us to locate the drug molecules in different locations giving us the flexibility to release them in a selected order. Core liposome (L2) has a melting temperature of 53.63 °C, it was decorated by gold nanoparticle (L2@AuNP) to bring photothermal responsiveness. The outer liposome structure had a lower melting temperature, which facilitated the sequential release process. The efficacy of photothermal therapy for nanosystem was calculated. The results indicate that coating L2@AuNP nanostructure with L1 liposomes improves efficacy by stabilizing gold nanoparticles. FOLFIRINOX components are encapsulated in a concentric liposome structure according to the order of administration into the body. The concentric liposome structure enables the sequential release of multiple drugs due to the varying phase transition temperatures of the liposomes. The cytotoxic effect of these formulations was evaluated on Panc-1 pancreatic cancer cells; the lowest cell viability was obtained in 4 Liposome(L) under 5 min NIR irradiation. Combination therapy has a higher therapeutic efficacy (70.45 %) when compared to chemotherapy and photothermal therapy used separately. The study's results show the potential of combination therapies to improve therapeutic outcomes, providing a promising path for future research and clinical application.

Nano-Delivery Materials: Review of Development and Application in Drug/Gene Transport

As the nanotechnology rapidly develops, the combination of nanotechnology and biotechnology to build nanoparticles with biological functionalization has brought new opportunities for the development and application of biomedical diagnosis. Many new non-viral drug/gene vectors were constructed by using nanoparticles as drug/gene carriers, especially by making conventional inorganic materials into nanoparticles and performing functional modifications. In this paper, the physical and chemical properties, preparation methods and application in drug/gene transport of several nanomaterials including mesoporous silica nanoparticles, gold nanoparticles, dendrimers, graphene oxide and carbon nanotubes are reviewed respectively. At the same time, the merit and dismerit of different nanocarriers and their application scenarios are compared. It has been found that the excellent biocompatibility and large specific surface area of inorganic nanomaterials have great potential for drug/gene delivery. Although there are many bottlenecks and challenges for nanomaterials to settle during drug delivery development and industrial production, the improvement of inorganic nanomaterials and the development of new nanocarriers can promote the wider progress of nanocarriers in drug/gene transport.

PHOTOCHEMICAL FABRICATION OF TRANSITION METAL NANOPARTICLES USING CdS TEMPLATE AND THEIR CO-CATALYSIS EFFECTS FOR TiO2 PHOTOCATALYSIS

Transition metal nanoparticles were prepared by chemical dissolution of CdS template from metal photodeposited CdS nanorod (length = 70–85 nm and width = 5–6 nm) heterocomposites. Size (9–10 nm) of metal nanoparticles obtained after CdS removal was larger than the size (4–6 nm) of metal nanodeposits over CdS template. The obtained Au nanoparticles displayed a broad red shifted absorption band at 660 nm, whereas Pt , Pd and Rh nanoparticles exhibit featureless absorption spectra. Elemental analysis confirms the complete removal of CdS template from Au – CdS ( Au — 2.65 at.%) and Ag – CdS ( Ag — 2.06 at.%) composites showing no Cd peak. These metal nanoparticles imparted dissimilar co-catalytic activity of TiO 2 for photocatalytic degradation of salicylic acid in the order Au > Pt > Pd > Ag > Rh as a function of their nature, electronegativity, redox potential and work function.

Preparation of various metal-silicate micro-balloons using W/O/W emulsion

Micron-sized inorganic microparticles with hollow insides were prepared by interfacial reaction method, in which an ion exchange reaction between Na(+) and metal cations in internal and external aqueous phases, respectively, proceeded through the oil phase involving a cation carrier. The diameter of microballoons was approximately 10 microm and shell thickness was below 2 microm. The effects of preparation conditions against the formation of microballoons were examined. The factors examined were metal species in the external aqueous phase and the concentrations of metal chloride and cation carrier. The cross-section of microparticles formed was inspected by scanning electron microscope (SEM) and the inner space of some metal silicates was not hollow but filled-up. The increase of internal and external aqueous solution concentrations caused the increase of diameter and shell thickness of microballoons. Since the penetration of metal cation through the oil phase was promoted by the increase of carrier concentration, the formation of microballoons was completed in a short time of less than 30 min.

Nanoparticle-assembled capsule synthesis: formation of colloidal polyamine-salt intermediates

There is current interest in developing new synthesis strategies for multifunctional hollow spheres with tunable structural properties that would be useful in encapsulation and controlled release applications. A new route was reported recently, in which the sequential reaction of polyamines, multivalent anions, and charged nanoparticles leads to the formation of polymer-filled and water-filled organic/inorganic micron-sized structures known as nanoparticle-assembled capsules. This technique is unique among other capsule preparation routes, as it allows the rapid and scalable formation of robust shells at room temperature, in near-neutral water, and with readily available precursors. This nanoparticle assembly synthesis route involves two steps: the formation of polymer aggregates and the subsequent deposition of particles around the aggregates. The purpose of this paper is to understand in greater detail the noncovalent chemistry of the polymer-salt aggregation step. With poly(allylamine hydrochloride) (PAH) as the model polymer, aggregate formation was investigated as a function of charge ratio, pH, and time through dynamic light scattering, electrophoretic mobility measurements, chloride ion measurements, and optical microscopy. PAH formed aggregates by the cross-linking action of divalent and higher-valent anions above a critical charge ratio and in a pH range defined by the pKa values of PAH and the anion. The aggregates grew in size through coalescence and with growth rates that depended on their surface charge. Controlling polymer aggregate growth provided a direct and simple means to adjust the size of the resultant capsule materials.

Latex and hollow particles of reactive polypyrrole: preparation, properties, and decoration by gold nanospheres

Polypyrrole-coated polystyrene latex particles bearing reactive N-amino functional groups (PS-PPyNH2) were prepared by the in-situ copolymerization of pyrrole (Py) and the active amino-functionalized pyrrole (PyNH2) in the presence of 1.33 microm-diameter polystyrene (PS) latex particles. These particles were prepared by dispersion polymerization of styrene using poly(N-vinylpyrrolidone), PNVP, as a steric stabilizer. The functionalized polypyrrole-coated PS particles (PS-PPyNH2) were characterized in terms of their particle size and surface morphology using transmission electron microscopy (TEM). Infrared and X-ray photoelectron spectroscopy (XPS) detected pyrrole-NH2 repeat units at the surface of the latex particles, indicating that this monomer had indeed copolymerized with pyrrole. The core-shell structure of the PS-PPyNH2 particles was confirmed by etching the polystyrene core in THF, leading to the formation of hollow conducting polymer capsules. The PS-PPyNH2 particles were then decorated with citrate-stabilized gold nanoparticles via electrostatic interactions. Furthermore, etching of the polystyrene core resulted in the formation of gold-decorated PPyNH2 hollow capsules.

Synthesis of silica-gold nanocomposites and their porous nanoparticles by an in-situ approach

We demonstrate the one-step synthesis of a silica-gold nanocomposite by simultaneous hydrolysis and reduction of gold chloride. The aminophenyl group was used as a reducing agent, and the trimethoxy silane group acts a precursor for the formation of silica. The porous gold nanoparticles were formed by etching out the silica-gold nanocomposite by hydrofluoric acid. The electron diffraction of porous gold nanoparticles showed that the particle are polycrystalline with FCC structure. The silica-gold nanocomposite exhibited nonlinear current-voltage behavior, and the porous gold nanoparticles displayed linear current-voltage behavior.

Reversible pH-Driven Conformational Switching of Tethered Superoxide Dismutase with Gold Nanoparticle Enhanced Surface Plasmon Resonance Spectroscopy

A new class of surface-immobilized protein nanomachines can be reversibly actuated by cycling the solution pH between 2.5 and 12.3, which induces a conformational change, thereby modulating the thickness of superoxide dismutase (SOD1) tethered to the Au thin film. By placing Au nanoparticles (AuNP) atop the immobilized SOD1 by means of a gold-thiol assembly, the nanoscale motion of SOD1 at the interface produces mechanical work to lift and then lower the AuNP from the Au substrate by a distance of ca. 3 nm and transduces this motion into an easily measurable reflectivity change in the surface plasmon resonance (SPR) spectrum. As-made supported conjugate consisting of SOD1 and AuNP is quite robust and stable, and its operation in response to pH variations, which mirrors the conformational changes of responsive SOD1 at the interface, is found to be highly reversible and reproducible. This is the first demonstration of the development of novel solid-state sensors and/or switching devices based on substrate-bound protein conformational changes and AuNP enhanced SPR spectroscopy.

Templated Assembly of Gold Nanoparticles into Microscale Tubules and Their Application in Surface-Enhanced Raman Scattering

We report a simple procedure to assemble gold nanoparticles into hollow tubular morphology with micrometer scale, wherein the citrate molecule is used not only as a reducing and capping agent, but also as an assembling template. The nanostructure and growth mechanism of microtubes are explored via SEM, TEM, FTIR spectra, and UV-vis spectra studies. The incorporation of larger gold nanoparticles by electroless plating results in an increase in the diameter of microtubes from 900 nm to about 1.2 microm. The application of the microtubes before and after electroless plating in surface-enhanced Raman scattering (SERS) is investigated by using 4-aminothiophenol (4-ATP) as probe molecules. The results indicate that the microtubes both before and after electroless plating can be used as SERS substrates. The microtubes after electroless plating exhibit excellent enhancement ability.

Gold Nanoparticles as a Colorimetric Sensor for Protein Conformational Changes

Spherical gold nanoparticles and flat gold films are prepared in which yeast iso-1-cytochrome c (Cyt c) is covalently bound to the gold surface by a thiol group in the cystein 102 residue. Upon exposure to solutions of different pH, bound Cyt c unfolds at low pH and refolds at high pH. This conformational change causes measurable shifts in the color of the coated nanoparticle solutions detected by UV-VIS absorption spectroscopy and in the refractive index (RI) of the flat gold films detected by surface plasmon resonance (SPR) spectroscopy. Both experiments demonstrate the same trend with pH, suggesting the use of protein-covered gold nanoparticles as a simple colorimetric sensor for conformational change.

Preparation and characterization of silver/TiO2 composite hollow spheres

Silver-coated poly(methyl acrylic acid) (PSA) core-shell colloid particles were prepared by an in situ chemical reduction method. Crystalline silver/titania composite hollow spheres were obtained by coating the as-prepared PSA/silver particles with an amorphous titania layer and subsequently calcining in Ar atmosphere. SEM and TEM investigation indicated that the size of the as-prepared PSA/silver and PSA/silver/TiO(2) core-shell particles and silver/titania composite hollow particles was fairly uniform and the wall thickness of the hollow spheres was in the range of 40-80 nm. UV-vis absorption spectra were recorded to investigate their optical properties.