One-step synthesis of positively charged bifunctional carbon dot/silver composite nanoparticles for killing and fluorescence imaging of Gram-negative bacteria.

Positively charged C-dot/Ag composite nanoparticles were synthesized via the facile one-step hydrothermal reaction of L-arginine and silver nitrate. L-arginine was used not only as the carbon and nitrogen sources of N-doped C-dots but also as the reducing agent of silver ions. It was noteworthy that the resulting C-dots were negatively charged but the simultaneous reduction of silver ions made the resulting C-dot/Ag composite nanoparticles become positively charged. Furthermore, as compared to C-dots, the presence of Ag nanoparticles and the higher nitrogen content led to the redshift of excitation and emission intervals. Also, the enlarged excitation wavelength range in the visible light region made the resulting C-dot/Ag nanocomposite more useful in fluorescence imaging. In addition, the C-dot/Ag composite nanoparticles exhibited more excellent bacteria-killing capability than C-dots and were successfully used for the fluorescence imaging of E. coli because they could attach and release silver ions on the surface of E. coli. In conclusion, a facile one-step hydrothermal process has been successfully developed for the synthesis of C-dot/Ag composite nanoparticles, and the resulting C-dot/Ag composite nanoparticles are expected to have great potential in the killing and fluorescence imaging of Gram-negative bacteria.

Electrochemical fabrication of nickel phosphide/reduced graphene oxide/nickel oxide composite on nickel foam as a high performance electrode for supercapacitors.

Three-dimensional (3D) nickel phosphide/reduced graphene oxide (rGO)/nickel oxide composite on nickel foam (Ni2P/rGO/NiO/NF) is fabricated as a supercapacitor (SC) electrode material via the two-step electrochemical deposition of graphene oxide (GO) and nickel phosphide on the nickel foam. Typically, rGO/NiO/NF is fabricated at first by the electrochemical treatment of nickel foam at 10 V in 0.1 M sulfuric acid with GO for 10 min. The result reveals that NiO nanosheets are vertically grown on the surface of nickel foam and rGO is deposited on the surface of NiO/NF, leading to the enhancement of capacity. Secondly, nickel phosphide is electrochemically deposited on the surface of rGO/NiO/NF in the sodium hypophosphite-based aqueous solution at 10 mA cm-2 to yield the Ni2P/rGO/NiO/NF. The deposition of Ni2P leads to a much higher capacity. The optimal areal and mass specific capacities are obtained as 3.59 C cm-2 and 742 C g-1 at the electrochemical deposition time of 30 and 10 min, respectively. The high capacity reveals that the proposed two-step electrochemical fabrication process is facile and effective. In addition, the Ni2P/rGO/NiO/NF electrode-based all-solid-state asymmetric SC was fabricated and could successfully turn on a light-emitting diode light. This revealed its feasibility in practical application and confirmed that the resulting 3D Ni2P/rGO/NiO/NF has a great potential as the SC electrode material.

One-step hydrothermal synthesis of three-dimensional porous Ni-Co sulfide/reduced graphene oxide composite with optimal incorporation of carbon nanotubes for high performance supercapacitors.

Three-dimensional (3D) porous Ni-Co sulfide/reduced graphene oxide composite with the appropriate incorporation of carbon nanotubes (NCS/rGO/CNT) was fabricated as a promising material for supercapacitor electrodes. It combined the high pseudo-capacitance of Ni-Co sulfide as well as the large specific surface area and electrical double layer capacitance of reduced graphene oxide (rGO). Carbon nanotubes (CNTs) were incorporated to act as the spacer for hindering the restacking of rGO and to construct a conductive network for enhancing the electron transport. The 3D porous NCS/rGO/CNT composite was fabricated by a facile one-step hydrothermal process in which Ni-Co sulfide nanosheets were synthesized and graphene oxide was reduced simultaneously. It was shown that the capacitance and cyclic performance indeed could be effectively improved via the appropriate addition of CNTs. In addition, a flexible all-solid-state asymmetric supercapacitor based on the NCS/rGO/CNT electrode was fabricated and exhibited the same capacitive electrochemical performance under bending. Also, it could successfully turn on a light-emitting diode light, revealing its feasibility in practical application. All results demonstrated that the developed NCS/rGO/CNT composite has potential application in supercapacitors.

Near-infrared light-responsive composite microneedles for on-demand transdermal drug delivery.

This study presents near-infrared (NIR) light-responsive polymer-nanostructure composite microneedles used for on-demand transdermal drug delivery. Silica-coated lanthanum hexaboride (LaB6@SiO2) nanostructures were incorporated into polycaprolactone microneedles, serving as an NIR absorber. When the microneedles were irradiated with NIR light, light-to-heat transduction mediated by the LaB6@SiO2 nanostructures caused the microneedle melting at 50 °C. This increased the mobility of the polymer chains, enabling drug release from the matrix. Drug release from the microneedles was evaluated for four laser on/off cycles. In each cycle, the samples were irradiated until the temperature reached 50 °C for 3 min (laser on); the laser was then turned off for 30 min (laser off). The results showed that light-induced phase transition in the polymer triggered drug release from the melted microneedles. A stepwise drug-release behavior was observed after multiple cycles of NIR light exposure. No notable drug leakage was found in the off state. This NIR-light-triggerable device exhibits excellent reproducibility, low off-state leakage, and noninvasive triggerability and, thus, represents an advance in transdermal delivery technology.

Cancer-cell-specific cytotoxicity of non-oxidized iron elements in iron core-gold shell NPs.

Gold-coated iron nanoparticles (NPs) selectively and significantly (P <0.0001) inhibit proliferation of oral- and colorectal-cancer cells in vitro at doses as low as 5 µg/mL, but have little adverse effect on normal healthy control cells. The particle treatment caused delay in cell-cycle progression, especially in the S-phase. There was no significant difference in the NP uptake between cancer and control cells, and cytotoxicity resulted primarily from the iron core, before oxidation, rather than from the Fe ions released from the core. In contrast with magnetic NPs that usually serve as drug carriers, diagnostic probes or hyperthermia media, the iron, before oxidation, in the NPs selectively suppressed cancer cell growth and left healthy control cells unaffected in vitro and in vivo. This novel nanomaterial holds great promise as a therapeutic tool in nanomedicine. FROM THE CLINICAL EDITOR: Gold-coated iron nanoparticles (NPs) selectively suppressed squamous cell carcinoma (SCC) and colorectal cancer (CRC) cell growth, but left healthy control cells unaffected both in vitro and in vivo. The particles were equally uptaken by all cells, but delayed cell progression only for cancer cells. The origin is related to the iron core: neither iron ions nor the oxidized NPs have the same outcome.

Synthesis and conductivity enhancement of Al-doped ZnO nanorod array thin films.

Al-doped ZnO (AZO) nanorod array thin films with various Al/Zn molar ratios were synthesized by chemical bath deposition. The resultant AZO nanorods were well-aligned at the glass substrate, growing vertically along the c-axis [001] direction. In addition, they had an average diameter of 64.7 +/- 16.8 nm and an average length of about 1.0 microm with the structure of wurtzite-type ZnO. Analyses of energy dispersive x-ray spectra and x-ray photoelectron spectra indicated that Al atoms had been doped into the ZnO crystal lattice. The doping of Al atoms did not result in significant changes in the structure and crystal orientation, but the electrical resistivity was found to increase first and then decrease with increasing Al content owing to the increase of carrier concentration and the decrease of mobility. In addition, the transmission in the visible region increased but the increase was reduced at higher Al doping levels. After hydrogen treatment, the morphology of the AZO nanorod array thin films remained unchanged. However, the electrical resistivity decreased significantly due to the formation of oxygen vacancies and interstitial hydrogen atoms. When the real Al/Zn molar ratio was about 3.7%, the conductivity was enhanced about 1000 times and a minimum electrical resistivity of 6.4 x 10( - 4) Omega cm was obtained. In addition, the transmission of the ZnO nanorod array thin film in the visible region was significantly increased but the increase was less significant for the AZO nanorod array thin film, particularly at higher Al doping levels. In addition, the current-voltage curves of the thin film devices with ZnO or AZO nanorod arrays revealed that AZO had a higher current response than ZnO and hydrogen treatment led to a more significant enhancement of current responses (about 100-fold).

Fabrication and temperature-dependent photoluminescence of silicon-silicon oxide core-shell nanoparticle thin film.

A novel Si nanocrystals embedded SiO2 thin film has been fabricated by the synthesis of Si-SiO2 core-shell (Si@SiO2) nanoparticles via the surface SiO2 coating of Si nanocrystals and the followed drop-coating on a silicon wafer. The resultant Si@SiO2 nanoparticles had a mean diameter of 30.43 +/- 2.63 nm and a mean shell thickness of 13.16 nm. They exhibited a stronger peak around 360 nm and a weaker green-yellow emission around 530 nm. The 360 nm peak could be attributed to the electron-hole recombination in the Si cores and that via the oxide-related defects originally present on the surface of oxide-passivated Si cores, while the green-yellow emission might be attributed to the transfer of the electron-hole pairs generated in the Si cores across the core-shell interface and the followed recombination in the SiO2 shells. The resultant Si@SiO2 nanoparticle thin film had a mean grain size of about 100 nm. It showed not only blue emission and green-yellow emission but also red emission which might be due to the transfer of the electron-hole pairs generated in the Si cores across the core-shell interface and the followed recombination via the Si==O double bonds at the particle surface. Because blue emission was significant relatively, both the Si@SiO2 nanoparticles and Si@SiO2 nanoparticle thin film still exhibited bright blue fluorescence under UV excitation. In addition, by investigating the temperature dependence of photoluminescence in the temperature range of 77 to 297 K, the nature of photoluminescence from the Si@SiO2 nanoparticle thin film was also clarified.

Structural characterization and self-assembly into superlattices of iron oxide-gold core-shell nanoparticles synthesized via a high-temperature organometallic route.

Iron oxide-gold core-shell nanocrystals have been synthesized by the thermal decomposition of iron pentacarbonyl and the subsequent reduction of gold acetate by 1,2-hexadecanediol with oleic acid and oleylamine as stabilizers. Their size, structure, composition, and optical and magnetic properties were characterized. The resultant nanoparticles were nearly monodisperse with a complete core-shell structure, and the shell thickness could be tuned via the seed-mediated growth. Also, they exhibited an absorption band at 520 nm owing to the surface plasmon resonance of Au shells and were nearly superparamagnetic due to the presence of the iron cores. By analyzing the x-ray adsorption near-edge structure (XANES) spectrum and the x-ray photoelectron spectroscopy (XPS) spectra of the fast etching mode, the iron cores were shown to be oxidized but the oxidation was incomplete in the inner region. Noteworthily, the iron oxide-Au nanoparticles could self-assemble into 2D and 3D superlattices. The packing density increased while approaching the center of assembly, leading to the variation of superstructures from a 2D nearly hcp monolayer to a 3D hcp superlattice and a 3D hexagonal superlattice. Moreover, hydrophilic iron oxide-Au core-shell nanoparticles were also obtained by surface modification with mercaptoacetic acid via a phase transfer route.

Fabrication and photocatalytic activities in visible and UV light regions of Ag@TiO2 and NiAg@TiO2 nanoparticles.

Completely discrete Ag@TiO2 and NiAg@TiO2 nanoparticles were prepared by the hydrazine reduction of Ag(+)/Ni(2+) ions and the subsequent sol-gel coating of TiO2 in an aqueous solution of CTAB. TEM analysis revealed that their core diameters were 6.55 +/- 1.20 and 7.57 +/- 1.33 nm, respectively, and their shell thicknesses were 2.59 and 2.80 nm, respectively. By the analyses of EDX, UV-vis absorption spectra, FTIR spectra, and zeta potential, their core-shell structure, crystal structure, optical properties, and surface state were demonstrated. In addition to exhibiting significant absorption in the visible light region, it was noted that they had lower zeta potentials than TiO2 nanoparticles, which favored the adsorption of positively charged organic compounds on the particle surface and thereby increased the photocatalytic reaction rate. By measuring the photocatalytic degradation rate of rhodamine B, Ag@TiO2 and NiAg@TiO2 nanoparticles were demonstrated to possess significantly higher photocatalytic activities than TiO2 nanoparticles in the visible light region because of the formation of Schottky barrier banding at the core-shell interface as well as the excitation of photogenerated electrons from the surface of Ag or NiAg cores to the conduction band of TiO2 shells. Although NiAg@TiO2 nanoparticles had lower photocatalytic activity than Ag@TiO2 nanoparticles owing to weaker surface plasmon resonance, they could be recovered magnetically from the treated solutions. Under UV light illumination, the photocatalytic activities of Ag@TiO2 and NiAg@TiO2 nanoparticles were lower than that of TiO2 nanoparticles because of the lower TiO2 content and the transfer of photogenerated electrons from TiO2 shells to Ag or NiAg cores, which also acted as the new recombination centers of photoinduced electrons and holes and hence led to a decrease in the photocatalytic activity.

A multifunctional magnetic nanocarrier bearing fluorescent dye for targeted drug delivery by enhanced two-photon triggered release.

We report a novel nanoformulation for targeted drug delivery which utilizes nanophotonics through the fusion of nanotechnology with biomedical application. The approach involves an energy-transferring magnetic nanoscopic co-assembly fabricated of rhodamine B (RDB) fluorescent dye grafted gum arabic modified Fe(3)O(4) magnetic nanoparticle and photosensitive linker by which dexamethasone drug is conjugated to the magnetic nano-assembly. The advantage offered by this nanoformulation is the indirect photo-triggered-on-demand drug release by efficient up-converting energy of the near-IR (NIR) light to higher energy and intraparticle energy transfer from the dye grafted magnetic nanoparticle to the linker for drug release by cleavage. The synthesized nanoparticles were found to be of ultra-small size (13.33 nm) and are monodispersed in an aqueous suspension. Dexamethasone (Dexa) drug conjugated to RDB-GAMNP by photosensitive linker showed appreciable release of Dexa by photo-triggered response on exposure to radiation having a wavelength in the NIR region whereas no detectable release was observed in the dark. Photo-triggered response for the nanoformulation not bearing the rhodamine B dye was drastically less as less Dexa was released on exposure to NIR radiation which suggest that the photo-cleavage of linker and release of Dexa mainly originated from the indirect excitation through the uphill energy conversions based on donor-acceptor model FRET. The promising pathway of nanophotonics for the on-demand release of the drug makes this nanocarrier very promising for applications in nanomedicine.

Rapid removal of heavy metal cations and anions from aqueous solutions by an amino-functionalized magnetic nano-adsorbent.

A novel magnetic nano-adsorbent has been developed by the covalent binding of polyacrylic acid (PAA) on the surface of Fe(3)O(4) nanoparticles and the followed amino-functionalization using diethylenetriamine (DETA) via carbodiimide activation. Transmission electron microscopy image showed that the amino-functionalized Fe(3)O(4) nanoparticles were quite fine with a mean diameter of 11.2+/-2.8 nm. X-ray diffraction analysis indicated that the binding process did not result in the phase change of Fe(3)O(4). Magnetic measurement revealed they were nearly superparamagnetic with a saturation magnetization of 63.2 emu/g Fe(3)O(4). The binding of DETA on the PAA-coated Fe(3)O(4) nanoparticles was demonstrated by the analyses of Fourier transform infrared (FTIR) spectroscopy and zeta potential. After amino-functionalization, the isoelectric point of PAA-coated Fe(3)O(4) nanoparticles shifted from 2.64 to 4.59. The amino-functionalized magnetic nano-adsorbent shows a quite good capability for the rapid and efficient adsorption of metal cations and anions from aqueous solutions via the chelation or ion exchange mechanisms. The studies on the adsorption of Cu(II) and Cr(VI) ions revealed that both obeyed the Langmuir isotherm equation. The maximum adsorption capacities and Langmuir adsorption constants were 12.43 mg/g and 0.06 L/mg for Cu(II) ions and 11.24 mg/g and 0.0165 L/mg for Cr(VI) ions, respectively.

Multifunctional pH-sensitive magnetic nanoparticles for simultaneous imaging, sensing and targeted intracellular anticancer drug delivery.

A novel multifunctional magnetic nanocarrier was fabricated for synchronous cancer therapy and sensing. The nanocarrier, programed to display a response to environmental stimuli (pH value), was synthesized by coupling doxorubicin (DOX) to adipic dihydrazide-grafted gum arabic modified magnetic nanoparticles (ADH-GAMNP) via the hydrolytically degradable pH-sensitive hydrazone bond. The resultant nanocarrier, DOX-ADH-GAMNP, had a mean diameter of 13.8 nm and the amount of DOX coupled was about 6.52 mg g(-1). Also, it exhibited pH triggered release of DOX in an acidic environment (pH 5.0) but was relatively stable at physiological pH (pH 7.4). Furthermore, both GAMNP and DOX were found to possess fluorescence properties when excited in the near-infrared region due to the two-photon absorption mechanism. The coupling of DOX to GAMNP resulted in a reversible self-quenching of fluorescence through the fluorescence resonant energy transfer (FRET) between the donor GAMNP and acceptor DOX. The release of DOX from DOX-ADH-GAMNP when exposed to acidic media indicated the recovery of fluorescence from both GAMNP and DOX. The change in the fluorescence intensity of DOX-ADH-GAMNP on the release of DOX can act as a potential sensor to sense the delivery of the drug. The analysis of zeta potential and plasmon absorbance in different pH conditions also confirmed the pH sensitivity of the product. This multifunctional nanocarrier is a significant breakthrough in developing a drug delivery vehicle that combines drug targeting as well as sensing and therapy at the same time.

Characterization of Iron Core⁻Gold Shell Nanoparticles for Anti-Cancer Treatments: Chemical and Structural Transformations During Storage and Use.

Finding a cancer-selective drug that avoids damaging healthy cells and organs is a holy grail in medical research. In our previous studies, gold-coated iron (Fe@Au) nanoparticles showed cancer selective anti-cancer properties in vitro and in vivo but were found to gradually lose that activity with storage or "ageing." To determine the reasons for this diminished anti-cancer activity, we examined Fe@Au nanoparticles at different preparation and storage stages by means of transmission electron microscopy combined with and energy-dispersive X-ray spectroscopy, along with X-ray diffraction analysis and cell viability tests. We found that dried and reconstituted Fe@Au nanoparticles, or Fe@Au nanoparticles within cells, decompose into irregular fragments of γ-F2O3 and agglomerated gold clumps. These changes cause the loss of the particles' anti-cancer effects. However, we identified that the anti-cancer properties of Fe@Au nanoparticles can be well preserved under argon or, better still, liquid nitrogen storage for six months and at least one year, respectively.

Fast removal of copper ions by gum arabic modified magnetic nano-adsorbent.

A novel magnetic nano-adsorbent was developed by treating Fe(3)O(4) nanoparticles with gum arabic to remove copper ions from aqueous solutions. Gum arabic was attached to Fe(3)O(4) via the interaction between the carboxylic groups of gum arabic and the surface hydroxyl groups of Fe(3)O(4). The surface modification did not result in the phase change of Fe(3)O(4), while led to the formation of secondary particles with diameter in the range of 13-67nm and the shift of isoelectric point from 6.78 to 3.6. The amount of gum arabic in the final product was about 5.1wt%. Both the naked magnetic nanoparticles (MNP) and gum arabic modified magnetic nanoparticles (GA-MNP) could be used for the adsorption of copper ions via the complexation with the surface hydroxyl groups of Fe(3)O(4) and the complexation with the amine groups of gum arabic, respectively. The adsorption rate was so fast that the equilibrium was achieved within 2min due to the absence of internal diffusion resistance and the adsorption capacities for both MNP and GA-MNP increased with increasing the solution pH. However, the latter was significantly higher than the former. Also, both the adsorption data obeyed the Langmuir isotherm equation. The maximum adsorption capacities were 17.6 and 38.5mg/g for MNP and GA-MNP, respectively, and the Langmuir adsorption constants were 0.013 and 0.012L/mg for MNP and GA-MNP, respectively. Furthermore, both the adsorption processes were endothermic due to the dehydration of hydrated metal ions. The enthalpy changes were 11.5 and 9.1kJ/mol for MNP and GA-MNP, respectively. In addition, the copper ions could desorb from GA-MNP by using acid solution and the GA-MNP exhibited good reusability.

Aqueous dispersions of magnetite nanoparticles with NH3+ surfaces for magnetic manipulations of biomolecules and MRI contrast agents.

In the current study, amine surface modified iron-oxide nanoparticles of 6 nm diameter without polymer coating were fabricated in an aqueous solution by organic acid modification as an adherent following chemical coprecipitation. Structure and the superparamagnetic property of magnetite nanoparticles were characterized by selected area electron diffraction (SAED) and superconducting quantum interference measurement device (SQUID). X-ray photoelectron spectrometer (XPS) and zeta potential measurements revealed cationic surface mostly decorated with terminal -NH(3)(+). This feature enables them to function as a magnetic carrier for nucleotides via electrostatic interaction. In addition, Fe(3)O(4)/trypsin conjugates with well-preserved functional activity was demonstrated. The nanoparticles displayed excellent in vitro biocompatibility. The NMR and the in vitro MRI measurements showed significantly reduced water proton relaxation times of both T(1) and T(2). Significantly reduced T(2) and T(2)*-weighted signal intensity were observed in a 1.5 T clinical MR imager. In vivo imaging contrast effect showed a fast and prolonged inverse contrast effect in the liver that lasted for more than 1 week. In addition, it was found that the spherical Fe(3)O(4) assembled as rod-like configuration through an aging process in aqueous solution at room temperature. Interestingly, TEM observation of the liver tissue revealed the rod-like shape but not the spherical-type nanoparticles being taken up by the Kupffer cells 120 h after tail vein infusion. Combining these results, we have demonstrated the potential applications of the newly synthesized magnetite nanoparticles in a broad spectrum of biomedical applications.

Adsorption kinetics and thermodynamics of acid dyes on a carboxymethylated chitosan-conjugated magnetic nano-adsorbent.

The monodisperse chitosan-conjugated Fe(3)O(4) nanoparticles with a mean diameter of 13.5 nm were fabricated by the carboxymethylation of chitosan and its covalent binding onto Fe(3)O(4) nanoparticles via carbodiimide activation. The carboxymethylated chitosan (CMCH)-conjugated Fe(3)O(4) nanoparticles with about 4.92 wt.-% of CMCH had an isoelectric point of 5.95 and were shown to be quite efficient as anionic magnetic nano-adsorbent for the removal of acid dyes. Both the adsorption capacities of crocein orange G (AO12) and acid green 25 (AG25), as the model compounds, decreased with increasing pH, and the decreasing effect was more significant for AO12. On the contrary, the increase in the ionic strength decreased the adsorption capacity of AG25 but did not affect, obviously, the adsorption capacity of AO12. By the addition of NaCl and NaOH, both AO12 and AG25 could desorb and their different desorption behavior could be attributed to the combined effect of pH and ionic strength. From the adsorption kinetics and thermodynamics studies, it was found that both the adsorption processes of AO12 and AG25 obeyed the pseudo-second-order kinetic model, Langmuir isotherm, and might be surface reaction-controlled. Furthermore, the time required to reach the equilibrium for each one was significantly shorter than those using the micro-sized adsorbents due to the large available surface area. Also, based on the weight of chitosan, the maximum adsorption capacities were 1 883 and 1 471 mg x g(-1) for AO12 and AG25, respectively, much higher than the reported data. Thus, the anionic magnetic nano-adsorbent could not only be magnetically manipulated but also possessed the advantages of fast adsorption rate and high adsorption capacity. This could be useful in the fields of separation and magnetic carriers. [formula in text].

Preparation and adsorption properties of monodisperse chitosan-bound Fe3O4 magnetic nanoparticles for removal of Cu(II) ions.

Monodisperse chitosan-bound Fe(3)O(4) nanoparticles were developed as a novel magnetic nano-adsorbent for the removal of heavy metal ions. Chitosan was first carboxymethylated and then covalently bound on the surface of Fe(3)O(4) nanoparticles via carbodiimide activation. Transmission electron microscopy micrographs showed that the chitosan-bound Fe(3)O(4) nanoparticles were monodisperse and had a mean diameter of 13.5 nm. X-ray diffraction patterns indicated that the magnetic nanoparticles were pure Fe(3)O(4) with a spinel structure, and the binding of chitosan did not result in a phase change. The binding of chitosan was also demonstrated by the measurement of zeta potential, and the weight percentage of chitosan bound to Fe(3)O(4) nanoparticles was estimated to be about 4.92 wt%. The chitosan-bound Fe(3)O(4) nanoparticles were shown to be quite efficient for the removal of Cu(II) ions at pH>2. In particular, the adsorption rate was so fast that the equilibrium was achieved within 1 min due to the absence of internal diffusion resistance. The adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 21.5 mg g(-1) and a Langmuir adsorption equilibrium constant of 0.0165 L mg(-1). The pH and temperature effects revealed that the adsorption capacity increased significantly with increasing pH at pH 2-5, and the adsorption process was exothermic in nature with an enthalpy change of -6.14 kJ mol(-1) at 300-330 K.

Highly Sensitive, Uniform, and Reusable Surface-Enhanced Raman Scattering Substrate with TiO2 Interlayer between Ag Nanoparticles and Reduced Graphene Oxide.

TiO2 nanoparticles and Ag nanoparticles were successively deposited on reduced graphene oxide (rGO) by a two-step solvothermal process to develop a reusable surface-enhanced Raman scattering (SERS) substrate with high sensitivity and uniformity owing to the 2-dimensional planar structure of rGO, the photocatalytic activity of TiO2, and the SERS function of Ag nanoparticles. The presence of TiO2 interlayer efficiently diminished the interference from the Raman intensities of D-band and G-band of rGO and hence enhanced the sensitivity significantly. As compared to Ag/rGO nanocomposite, the detection limit of 4-aminothiophenol (4-ATP) for Ag/TiO2/rGO nanocomposite could be lowered from 10(-10) to 10(-14) M, and its enhancement factor could be raised from 1.27 × 10(10) to 3.46 × 10(12). Meanwhile, good uniformity remained, the relative standard deviation (RSD) value was about 10%. Furthermore, by UV irradiation in water, the photocatalytic property of TiO2 could eliminate the Raman signal of 4-ATP efficiently and made this substrate reusable. After being reused five times, its excellent SERS performance was still retained. Thus, the Ag/TiO2/rGO nanocomposite developed in this work was a promising SERS substrate with good reusability and high sensitivity and uniformity.

Remotely triggered release of small molecules from LaB6@SiO2-loaded polycaprolactone microneedles.

We established near-infrared (NIR)-light-triggered transdermal delivery systems by encapsulating NIR absorbers, silica-coated lanthanum hexaboride (LaB6@SiO2) nanostructures and the cargo molecule to be released in biodegradable polycaprolactone (PCL) microneedles. Acting as a local heat source when exposed to an NIR laser, these nanostructures cause a phase transition of the microneedles, thereby increasing the mobility of the polymer chains and triggering drug release from the microneedles. On IR thermal images, the light-triggered melting behavior of the LaB6@SiO2-loaded microneedles was observed. By adjusting the irradiation time and the laser on/off cycles, the amount of molecules released was controlled accurately. Drug release was switched on and off for at least three cycles, and a consistent dose was delivered in each cycle with high reproducibility. The designed microneedles were remotely triggered by laser irradiation for the controlled release of a chemotherapeutic drug, doxorubicin hydrochloride, in vivo. This system would enable dosages to be adjusted accurately to achieve a desired effect, feature a low off-state drug leakage to minimize basal effects and can increase the flexibility of pharmacotherapy performed to treat various medical conditions.