One-step shell polymerization of inorganic nanoparticles and their applications in SERS/nonlinear optical imaging, drug delivery, and catalysis

Fabrication of an Au-doped Cu/Fe oxide-polymer core-shell nanoreactor with chemodynamic and photodynamic dual effects as potential cancer therapeutic agents

Nanoparticles are widely used in biomedical applications and cancer treatments due to their minute scale, multi-function, and long retention time. Among the various nanoparticles, the unique optical property derived from the localized surface plasmon resonance effect of metallic nanoparticles is a primary reason that metallic nanoparticles are researched and applied. Copper and Iron nanoparticles have the potential to generate hydroxyl radicals in excess H₂O₂ via Fenton or Fenton-like reactions. On the other hand, gold nanoparticles equipped with a photosensitizer can transfer the energy of photons to chemical energy and enhance the production of singlet oxygen, which is suitable for cancer treatment. With the actions of these two reactive oxygen species in the tumor microenvironment, cell apoptosis can further be induced. In this work, we first synthesized dual metal nanoparticles with poly[styrene-alt-(maleic acid, sodium salt)(Cu ferrite oxide-polymer) by a simple one-step hydrothermal reduction reaction. Then, gold(III) was reduced and doped into the structure, which formed a triple metal structure, Au-doped Cu ferrite nanoparticles (Au/Cu ferrite oxide-polymer NPs). The metal ratio of the product could be controlled by manipulating the Fe/Cu ratio of reactants and the sequence of addition of reactants. The core-shell structure was verified by transmission electron microscopy. Moreover, the hydroxyl radical and singlet oxygen generation ability of Au/Cu ferrite oxide-polymer was proved. The chemodynamic and photodynamic effect was measured, and the in vitro ROS generation was observed. Furthermore, the behavior of endocytosis by cancer cells could be controlled by the magnetic field. The result indicated that Au/Cu ferrite oxide-polymer core-shell nanoreactor is a potential agent for chemodynamic/photodynamic synergetic therapy.

A universal strategy for the fabrication of single-photon and multiphoton NIR nanoparticles by loading organic dyes into water-soluble polymer nanosponges

The development of optical organic nanoparticles (NPs) is desirable and widely studied. However, most organic dyes are water-insoluble such that the derivatization and modification of these dyes are difficult. Herein, we demonstrated a simple platform for the fabrication of organic NPs designed with emissive properties by loading ten different organic dyes (molar masses of 479.1–1081.7 g/mol) into water-soluble polymer nanosponges composed of poly(styrene-alt-maleic acid) (PSMA). The result showed a substantial improvement over the loading of commercial dyes (3.7–50% loading) while preventing their spontaneous aggregation in aqueous solutions. This packaging strategy includes our newly synthesized organic dyes (> 85% loading) designed for OPVs (242), DSSCs (YI-1, YI-3, YI-8), and OLEDs (ADF-1–3, and DTDPTID) applications. These low-cytotoxicity organic NPs exhibited tunable fluorescence from visible to near-infrared (NIR) emission for cellular imaging and biological tracking in vivo. Moreover, PSMA NPs loaded with designed NIR-dyes were fabricated, and photodynamic therapy with these dye-loaded PSMA NPs for the photolysis of cancer cells was achieved when coupled with 808 nm laser excitation. Indeed, our work demonstrates a facile approach for increasing the biocompatibility and stability of organic dyes by loading them into water-soluble polymer-based carriers, providing a new perspective of organic optoelectronic materials in biomedical theranostic applications.

Polyaniline-Based Glyco-Condensation on Au Nanoparticles Enhances Immunotherapy in Lung Cancer

Lung cancer is considered among the deadliest cancers with a poor prognosis. Au@PG nanoparticles (NPs) are gold (Au)-based NPs featuring a polyaniline-based glyco structure (PG) generated from the polymerization of ortho-nitrophenyl-β-d-galactopyranoside (ONPG) with promising M1 macrophage polarization activity, resulting in tumor remodeling and from a cold to a hot microenvironment, which promotes the cytotoxic T cell response and tumor inhibition. The combination of Au@PG NPs and anti-programmed cell death protein 1 (PD-1) therapy improved tumor inhibition and immunosuppression, accompanied by the secretion of immunogenic cytokines. A one-pot synthetic method was developed to achieve glyco-condensation during the formation of Au@PG NPs, which induced macrophage polarization more efficiently than Au@glucose, Au@mannose, and Au@galactose NPs. The switch from M2 to M1 macrophages was dependent on NP size, with smaller Au@PG NPs performing better than larger ones, with effectiveness ranked as follows: 32.2 nm ≈ 29.8 nm < 26.4 nm < 18.3 nm. Cellular uptake by endocytosis induced size-dependent endoplasmic reticulum (ER) stress, which resulted in the activation of spleen tyrosine kinase (SYK), leading to immune modulations and macrophage polarization. Our results suggested the promising potential of Au@PG NPs in lung cancer immunotherapy.

Hybrid Inorganic-Organic Core-Shell Nanodrug Systems in Targeted Photodynamic Therapy of Cancer

Hybrid inorganic-organic core-shell nanoparticles (CSNPs) are an emerging paradigm of nanodrug carriers in the targeted photodynamic therapy (TPDT) of cancer. Typically, metallic cores and organic polymer shells are used due to their submicron sizes and high surface to volume ratio of the metallic nanoparticles (NPs), combined with enhances solubility, stability, and absorption sites of the organic polymer shell. As such, the high loading capacity of therapeutic agents such as cancer specific ligands and photosensitizer (PS) agents is achieved with desired colloidal stability, drug circulation, and subcellular localization of the PS agents at the cancer site. This review highlights the synthesis methods, characterization techniques, and applications of hybrid inorganic-organic CSNPs as loading platforms of therapeutic agents for use in TPDT. In addition, cell death pathways and the mechanisms of action that hybrid inorganic-organic core-shell nanodrug systems follow in TPDT are also reviewed. Nanodrug systems with cancer specific properties are able to localize within the solid tumor through the enhanced permeability effect (EPR) and bind with affinity to receptors on the cancer cell surfaces, thus improving the efficacy of short-lived cytotoxic singlet oxygen. This ability by nanodrug systems together with their mechanism of action during cell death forms the core basis of this review and will be discussed with an overview of successful strategies that have been reported in the literature.

Effect of ROS generation on highly dispersed 4-layer O-Ti7O13 nanosheets toward tumor synergistic therapy

Ultra-thin two-dimensional nanosheets have attracted increasing attention due to their great application prospects in nanomaterial science and biomedicine. Herein, we report the preparation of exfoliated raw and oxidized 4-layer Ti₇O₁₃ (O-Ti₇O₁₃) and their ability to produce reactive oxygen species (ROS). The results show that O-Ti₇O₁₃ nanosheets can effectively produce ROS induced by X-ray irradiation. The 4-layer nanosheets can quickly load doxorubicin (DOX) within 5 min with a high loading rate to obtain a novel nanodrug system through their electrostatic adsorption capacity, and they exhibit a sustained release behavior. In this way, chemotherapy, radiation therapy and photodynamic therapy effectively combine for cancer synergistic treatment. We evaluated the cytotoxicity, cellular uptake and intracellular location of the O-Ti₇O₁₃ nanosheet-based drug delivery system in A549 lung cancer cells. Our results show that the O-Ti₇O₁₃/DOX complex is more cytotoxic to A549 cells than free DOX since a low concentration of loaded DOX (10 μg/mL) with a low dose of X-rays can cause the complete apoptosis of tumor cells. This work reveals that the therapeutic effect of DOX-loaded O-Ti₇O₁₃ nanosheets is strongly dependent on their loading mode, and the effects of chemotherapy and photodynamic therapy are enhanced under X-ray irradiation, which allows O-Ti₇O₁₃ nanosheet use as a photo-activated drug carrier. This work provides a new strategy for preparing 2D metal oxide nanosheets toward biomedical applications.

Fabrication of Anisotropic Cu Ferrite-Polymer Core-Shell Nanoparticles for Photodynamic Ablation of Cervical Cancer Cells

In this work we developed methylene blue-immobilized copper-iron nanoparticles (MB-CuFe NPs) through a facile one-step hydrothermal reaction to achieve a better phototherapeutic effect. The Fe/Cu ratio of the CuFe NPs was controllable by merely changing the loading amount of iron precursor concentration. The CuFe NPs could serve as a Fenton catalyst to convert hydrogen peroxide (H2O2) into reactive oxygen species (ROS), while the superparamagnetic properties also suggest magnetic resonance imaging (MRI) potential. Furthermore, the Food and Drug Administration (FDA)-approved MB photosensitizer could strongly adsorb onto the surface of CuFe NPs to facilitate the drug delivery into cells and improve the photodynamic therapy at 660 nm via significant generation of singlet oxygen species, leading to enhanced cancer cell-damaging efficacy. An MTT (thiazolyl blue tetrazolium bromide) assay proved the low cytotoxicity of the CuFe NPs to cervical cancer cells (HeLa cells), namely above 80% at 25 ppm of the sample dose. A slight dissolution of Cu and Fe ions from the CuFe NPs in an acidic environment was obtained, providing direct evidence for CuFe NPs being degradable without the risk of long-term retention in the body. Moreover, the tremendous photo-to-thermal conversion of CuFe NPs was examined, which might be combined with photodynamic therapy (PDT) for promising development in the depletion of cancer cells after a single pulse of deep-red light irradiation at high laser power.

Silver-chitosan nanocomposite as a plasmonic platform for SERS sensing of polyaromatic sulfur heterocycles in oil fuel

Herein, a silver-chitosan nanocomposite for application in surface enhanced Raman spectroscopy (SERS) sensing was proposed. It was shown that optically transparent chitosan coatings with 0.8 μm thickness allow penetration of target analytes to silver nanoparticles and the analysis in both polar and nonpolar solvents. Under the chosen conditions, chitosan formed continuously smooth films and coatings stabilizing rough nanostructured metallic surfaces and served as a suitable matrix for immobilization, uniform spreading, and preconcentration of the analytes. Polycyclic aromatic sulfur heterocycles were chosen as target analytes being one of the most important fuel quality markers, hazardous components, and the hardest-to-remove impurities. For the most effective immobilization and even distribution of the analytes onto a nanostructured metallic surface, an additional polymer layer of chitosan was found to be needed. The presence of thin films of chitosan resulted in higher reproducibility of SERS spectra as compared to bare nanostructured silver substrates. Additionally, the developed nanocomposite SERS sensors provided the rapid determination of dibenzothiophene and its derivatives in isooctane with the threshold of detection better than 0.1 μM. This approach was successfully applied in the analysis of real fuel samples and the results agreed well with independently measured FTIR and GC-MS data.

One-step synthesis of phyto-polymer coated gold nanospheres as a delivery system to enhance resveratrol cytotoxicity

This study introduces a simple method for one-step synthesis of highly stable nontoxic polymer-coated gold nanospheres for use in drug delivery, focuses on the ability of chloroauric acid (HAu Cl4 ) to induce polyphenols polymerization, puts up an easy procedure for loading hydrophobic drugs onto gold nanoparticles with ultra-high loading efficiency and studies the cytotoxicity of free and gold nanoparticles-loaded resveratrol. Gold nanospheres were synthesized simply by direct reaction between resveratrol itself and HAu Cl4 in aqueous medium. Synthesized gold nanospheres exhibited high stability in both aqueous and ethanolic solutions. UV-visible spectrum showed that the synthesized gold nanospheres have maximum absorption at 532 nm. TEM imaging, mass and FT-IR spectrometry revealed the presence of a distinct polymeric shell around each nanoparticle. Resveratrol, as a chemopreventive agent, was loaded onto the synthesized gold nanospheres with an ultra-high loading capacity (11.6% w/w). Free resveratrol, free gold nanospheres, and resveratrol-loaded gold nanospheres were examined for cytotoxicity on HepG2 cell line where cytotoxicity of loaded resveratrol was dramatically enhanced to reach about nine folds as that of free resveratrol at the same concentration.

Detection of Histamine Dihydrochloride at Low Concentrations Using Raman Spectroscopy Enhanced by Gold Nanostars Colloids

In this paper, we report a fast and easy method to detect histamine dihydrochloride using gold nanostars in colloidal aqueous solution as a highly active SERS platform with potential applications in biomedicine and food science. This colloid was characterized with SEM and UV⁻Vis spectroscopy. Also, numerical calculations were performed to estimate the plasmonic resonance and electric field amplification of the gold nanoparticles to compare the difference between nanospheres and nanostars. Finally, aqueous solutions of histamine dihydrochloride were prepared in a wide range of concentrations and the colloid was added to carry out SERS. We found SERS amplified the Raman signal of histamine by an enhancement factor of 1 . 0 × 10 7 , demonstrating the capability of the method to detect low concentrations of this amine molecule.

Syringeable Self-Organizing Gels that Trigger Gold Nanoparticle Formation for Localized Thermal Ablation

Block copolymer dispersions that form gels at body temperature and that additionally are able to reduce a gold salt to nanoparticles (AuNPs) directly in the final formulation under mild conditions were designed as hybrid depots for photothermal therapy. The in situ gelling systems may retain AuNPs in the application zone for a long time so that localized elevations of temperature can be achieved each time the zone is irradiated. To carry out the work, dispersions were prepared covering a wide range of poloxamine Tetronic 1307:gold salt molar ratios in NaCl media (also varying from pure water to hypertonic solution). Even at copolymer concentrations well above the critical micelle concentration, the reducing power of the copolymer was maintained, and AuNPs were formed in few hours without extra additives. Varying the copolymer and NaCl concentrations allowed a fine tuning of nanoparticles' shape from spherical to triangular nanoplates, which determined that the surface plasmon resonance showed a maximum intensity at 540 nm or at 1000 nm, respectively. The information gathered on the effects of (i) the poloxamine concentration on AuNPs' size and shape under isotonic conditions, (ii) the AuNPs on the temperature-induced gelling transition, and (iii) the gel properties on the photothermal responsiveness of the AuNPs during successive irradiation cycles may help the rational design of one-pot gels with built-in temperature and light responsiveness.

The effect of low- and high-penetration light on localized cancer therapy

The design of a delivery system allowing targeted and controlled drug release has been considered one of the main strategies used to provide individualized cancer therapy, to improve survival statistics, and to enhance quality-of-life. External stimuli including low- and high-penetration light have been shown to have the ability to turn drug delivery on and off in a non-invasive remotely-controlled fashion. The success of this approach has been closely related to the development of a variety of drug delivery systems - from photosensitive liposomes to gold nanocages - and relies on multiple mechanisms of drug release activation. In this review, we make reference to the two extremes of the light spectrum and their potential as triggers for the delivery of antitumor drugs, along with the most recent achievements in preclinical trials and the challenges to an efficient translation of this technology to the clinical setting.

Methylene-Blue-Encapsulated Liposomes as Photodynamic Therapy Nano Agents for Breast Cancer Cells

Methylene blue (MB) is a widely used dye and photodynamic therapy (PDT) agent that can produce reactive oxygen species (ROS) after light exposure, triggering apoptosis. However, it is hard for the dye to penetrate through the cell membrane, leading to poor cellular uptake; thus, drug carriers, which could enhance the cellular uptake, are a suitable solution. In addition, the defective vessels resulting from fast vessel outgrowth leads to an enhanced permeability and retention (EPR) effect, which gives nanoscale drug carriers a promising potential. In this study, we applied poly(12-(methacryloyloxy)dodecyl phosphorylcholine), a zwitterionic polymer-lipid, to self-assemble into liposomes and encapsulate MB (MB-liposome). Its properties of high stability and fast intracellular uptake were confirmed, and the higher in vitro ROS generation ability of MB-liposomes than that of free MB was also verified. For in vivo tests, we examined the toxicity in mice via tail vein injection. With the features found, MB-liposome has the potential of being an effective PDT nano agent for cancer therapy.

Facing Challenges in Real-Life Application of Surface-Enhanced Raman Scattering: Design and Nanofabrication of Surface-Enhanced Raman Scattering Substrates for Rapid Field Test of Food Contaminants

Surface-enhanced Raman scattering (SERS) is capable of detecting a single molecule with high specificity and has become a promising technique for rapid chemical analysis of agricultural products and foods. With a deeper understanding of the SERS effect and advances in nanofabrication technology, SERS is now on the edge of going out of the laboratory and becoming a sophisticated analytical tool to fulfill various real-world tasks. This review focuses on the challenges that SERS has met in this progress, such as how to obtain a reliable SERS signal, improve the sensitivity and specificity in a complex sample matrix, develop simple and user-friendly practical sensing approach, reduce the running cost, etc. This review highlights the new thoughts on design and nanofabrication of SERS-active substrates for solving these challenges and introduces the recent advances of SERS applications in this area. We hope that our discussion will encourage more researches to address these challenges and eventually help to bring SERS technology out of the laboratory.

Degradable NIR-PTT Nanoagents with a Potential Cu@Cu2O@Polymer Structure

Cu@Cu₂O@PSMA polymer nanoparticles (Cu@Cu₂O@polymer NPs) with near-infrared (NIR) absorption were successfully synthesized in a single-step oxidation reaction of Cu@PSMA polymer NPs at 100 °C for 20 min. The shape, structure, and optical properties of the Cu@Cu₂O@polymer NPs were tailorable by controlling the reaction parameters, for example, using the initial Cu@PSMA polymer NP as a template and varying the halide ion content, heating temperature, and reaction time. The Cu@Cu₂O@polymer NPs exhibited robust NIR absorption between 650 and 710 nm and possessed superior oxidation resistance in water and culture media. In vitro assays demonstrated the low cytotoxicity of the Cu@Cu₂O@PSMA polymer NPs to HeLa cells through an improved cell viability, high IC₅₀, low injury incidence from the supernatant of the partly dissociated Cu@Cu₂O@PSMA polymer NPs, and minor generation of reactive oxygen species. More importantly, we demonstrated that the inorganic Cu-based nanocomposite [+0.34 V vs normal hydrogen electrode (NHE)] was degradable in an endogenous H₂O₂ (+1.78 V vs NHE) environment. Cu ions were detected in the urine of mice, which illustrates the possibility of extraction after the degradation of the Cu-based particles. 'After an treatment of the HeLa cells with the Cu@Cu₂O@polymer NPs and a 660 nm light-emitting diode, the photoablation of 50 and 90% cells was observed at NP doses of 20 and 50 ppm, respectively. These results demonstrate that NIR-functional and moderate redox-active Cu@Cu₂O@polymer NPs are potential next-generation photothermal therapy (PTT) nanoagents because of combined features of degradation resistance in the physiological environment, enabling the delivery of efficient PTT, a possibly improved ability to selectively harm cancer cells by releasing Cu ions under high-H₂O₂ and/or low-pH conditions, and ability to be extracted from the body after biodegradation.

Plasmonic Near-Field Localization of Silver Core-Shell Nanoparticle Assemblies via Wet Chemistry Nanogap Engineering

Silver nanoparticles are widely used in the field of plasmonics because of their unique optical properties. The wavelength-dependent surface plasmon resonance gives rise to a strongly enhanced electromagnetic field, especially at so-called hot spots located in the nanogap in-between metal nanoparticle assemblies. Therefore, the interparticle distance is a decisive factor in plasmonic applications, such as surface-enhanced Raman spectroscopy (SERS). In this study, the aim is to engineer this interparticle distance for silver nanospheres using a convenient wet-chemical approach and to predict and quantify the corresponding enhancement factor using both theoretical and experimental tools. This was done by building a tunable ultrathin polymer shell around the nanoparticles using the layer-by-layer method, in which the polymer shell acts as the separating interparticle spacer layer. Comparison of different theoretical approaches and corroborating the results with SERS analytical experiments using silver and silver-polymer core-shell nanoparticle clusters as SERS substrates was also done. Herewith, an approach is provided to estimate the extent of plasmonic near-field enhancement both theoretically as well as experimentally.

Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications

Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

Nanostructure-based surface-enhanced Raman scattering biosensors for nucleic acids and proteins

Detection of nucleic acid and protein targets related to human health and safety has attracted widespread attention. Surface-enhanced Raman scattering (SERS) is a powerful tool for biomarker detection because of its ultrahigh detection sensitivity and unique fingerprinting spectra. In this review, we first introduce the development of nanostructure-based SERS-active substrates and SERS nanotags, which greatly influence the performance of SERS biosensors. We then focus on recent advances in SERS biosensors for DNA, microRNA and protein determination, including label-free, labeled and multiplex analyses as well as in vivo imaging. Finally, the prospects and challenges of such nanostructure-based SERS biosensors are discussed.

OFF/ON galvanic replacement reaction for preparing divergent AuAg nano-hollows as a SERS-visualized drug delivery system in targeted photodynamic therapy

3-D AuAg nano-hollows were fabricated by an anti-galvanic replacement reaction (off), followed by a proton exchange reaction (on). They exhibited superior Raman detection sensitivity for potentially imaging-guided and folic acid-targeted photodynamic therapy of cancer cells.

Controlled Au-Polymer Nanostructures for Multiphoton Imaging, Prodrug Delivery, and Chemo-Photothermal Therapy Platforms

We have successfully introduced a proton-induced controlled reaction of HAuCl4 and poly(styrene-alt-maleic acid) (PSMA) sodium salt to prepare triangular and multicore Au@polymer nanoparticles (NPs). The interparticle interactions in the core gave rise to an absorption band at the near-infrared wavelength. The near-infrared optical properties of the resulting Au-polymer nanostructures are highly stable in a physiological environment, which offered strong photo-to-thermal conversion by a moderate continuous-wave 808 nm laser and exhibited multiphoton fluorescence for imaging using a 1230 nm light excitation (femtosecond laser). Exposure of the carboxylate groups at the polymer shell made the surface structure of the Au multicore @polymer NPs directly conjugate Pt(II)-/Pt(IV)-based drugs, which possessed the elimination of the immediate toxicity over the short time and resulted in an anticancer effect after 3 days. A synergistic effect of the chemo-photothermal therapy showed a moderate hyperthermia assistance (<1 W/cm(2)) and better anticancer performance over time compared with the individual treatments. We demonstrated that such PSMA-based methodology not only enables a broad range of chemical material synthesis in the kinetic control to form Au nano-octahedrons and nanotriangles using Br(-)/I(-) ions additives but also could be extended to form Au/Fe3O4@polymer nanocomposites via proton-assisted PSMA self-assembly.

Potential Health Impact of Environmentally Released Micro- and Nanoplastics in the Human Food Production Chain: Experiences from Nanotoxicology

High concentrations of plastic debris have been observed in the oceans. Much of the recent concern has focused on microplastics in the marine environment. Recent studies of the size distribution of the plastic debris suggested that continued fragmenting of microplastics into nanosized particles may occur. In this review we assess the current literature on the occurrence of environmentally released micro- and nanoplastics in the human food production chain and their potential health impact. The currently used analytical techniques introduce a great bias in the knowledge, since they are only able to detect plastic particles well above the nanorange. We discuss the potential use of the very sensitive analytical techniques that have been developed for the detection and quantification of engineered nanoparticles. We recognize three possible toxic effects of plastic particles: first due to the plastic particles themselves, second to the release of persistent organic pollutant adsorbed to the plastics, and third to the leaching of additives of the plastics. The limited data on microplastics in foods do not predict adverse effect of these pollutants or additives. Potential toxic effects of microplastic particles will be confined to the gut. The potential human toxicity of nanoplastics is poorly studied. Based on our experiences in nanotoxicology we prioritized future research questions.

Unexpected in-situ Free Radical Generation and Catalysis to Ag/Polymer Nanocomposite

In this study, we discover unexpectedly that simple reaction of AgNO₃ with oleic acid (OA) without solvent and surfactant could generate alkyl free radical which can catalyze double-bond polymerization of OA to form 1D polymeric oleic acid (POA) chain. In certain conditions, these POA chains circumvolute tightly each other to form microspheres and micro-plates in which monodisperse 4-5 nm Ag nanoparticles (NPs) were absorbed. It has been revealed that alkyl free radical generated during the redox reaction of carboxyl group of OA with Ag⁺ at relative low temperature. Then, the alkyl free radical catalyzed the double-bond polymerization of OA when the reaction temperature was further increased. Different from commonly-seen hydrophobic nanoparticles prepared in oleic acid-based microemulsion system, the nanocomposites cannot dispersed in n-hexane and could dispersed in ethanol and THF. The unusual dispersion behavior has been explained in terms of their structure and polarity of POA chain. The method combines the nucleation of Ag nanoparticles and the polymerization of monomer in a facile one-pot reaction, which provides a novel way for metal-polymer microsphere nanocomposite with low-cost, easy-operation and high-yield.

Enhanced Raman sensitivity and magnetic separation for urolithiasis detection using phosphonic acid-terminated Fe3O4 nanoclusters

Surface-functionalized Fe₃O₄ nanoparticles are emerging as promising agents for the selective and magnetic separation of various biological molecules. In principle, by engineering the surface of Fe₃O₄ nanoparticles, they can be applied as tracers to seek and recognize metabolites and secretions of specific diseases. In this report, we developed Fe₃O₄ nanoclusters with high magnetization and an amino-functionalized surface via the reaction between FeCl₂, a hydrazine reductant, and a gelatin polymer to demonstrate magnetically separated prevalent urinary crystals. The surface of the gelatin-coated Fe₃O₄ nanoclusters was modified by using aminopropylphosphonic acid by amine coupling using EDC and NHS, which led to the exposure of their phosphonic acid groups and improved their affinity for fine Ca-based urinary crystals in the patient's urine. By subjecting the Fe₃O₄ nanoclusters that were bound to urinary crystals to Raman spectroscopy analysis, the crystalline types of the pre-concentrated urinary components were easily identified. The assignment of the vibration peaks of the crystals is promising for eliminating the false positives that occur when using a microscopic analysis method for urine crystal diagnosis. Sample preparation and identification required less than 10 min. Finally, we demonstrated that this non-invasive analytic platform exhibits a rapid and efficient detection rate of single- and multi-component urinary crystals from urine metabolites. A good correlation (86%) was observed between this non-invasive analytic platform and the diagnostic reports from 35 urolithiasis patients. We expect that this Fe₃O₄ nanocluster integrated Raman spectrum method will provide crystal information that could help early management for urolithiasis patients.

Development of therapeutic Au-methylene blue nanoparticles for targeted photodynamic therapy of cervical cancer cells

Photodynamic therapy (PDT) involves the cellular uptake of a photosensitizer (PS) combined with oxygen molecules and light at a specific wavelength to be able to trigger cancer cell death via the apoptosis pathway, which is less harmful and has less inflammatory side effect than necrosis. However, the traditional PDT treatment has two main deficiencies: the dark toxicity of the PS and the poor selectivity of the cellular uptake of PS between the target cells and normal tissues. In this work, methylene blue (MB), a known effective PS, combined with Au nanoparticles (NPs) was prepared using an intermolecular interaction between a polystyrene-alt-maleic acid (PSMA) layer on the Au NPs and MB. The Au@polymer/MB NPs produced a high quantum yield of singlet oxygen molecules, over 50% as much as that of free MB, when they were excited by a dark red light source at 660 nm, but without significant dark toxicity. Furthermore, transferrin (Tf) was conjugated on the Au@polymer/MB NPs via an EDC/NHS reaction to enhance the selectivity to HeLa cells compared to 3T3 fibroblasts. With a hand-held single laser treatment (32 mW/cm) for 4 min, the new Au@polymer/MB-Tf NPs showed a 2-fold enhancement of PDT efficiency toward HeLa cells over the use of free MB at 4 times dosage. Cellular staining examinations showed that the HeLa cells reacted with Au@polymer/MB-Tf NPs and the 660 nm light excitation triggered PDT, which caused the cells to undergo apoptosis ("programmed" cell death). We propose that applying this therapeutic Au@polymer/MB-Tf nanoagent is facile and safe for delivery and cancer cell targeting to simultaneously minimize side effects and accomplish a significant enhancement in photodynamic therapeutic efficiency toward next-generation nanomedicine development.