The optical, photothermal, and facile surface chemical properties of gold and silver nanoparticles in biodiagnostics, therapy, and drug delivery

Silver Nanoparticle-Based Fluorescence-Quenching Lateral Flow Immunoassay for Sensitive Detection of Ochratoxin A in Grape Juice and Wine

A silver nanoparticle (AgNP)-based fluorescence-quenching lateral flow immunoassay with competitive format (cLFIA) was developed for sensitive detection of ochratoxin A (OTA) in grape juice and wine samples in the present study. The Ru(phen)32+-doped silica nanoparticles (RuNPs) were sprayed on the test and control line zones as background fluorescence signals. The AgNPs were designed as the fluorescence quenchers of RuNPs because they can block the exciting light transferring to the RuNP molecules. The proposed method exhibited high sensitivity for OTA detection, with a detection limit of 0.06 µg/L under optimized conditions. The method also exhibited a good linear range for OTA quantitative analysis from 0.08 µg/L to 5.0 µg/L. The reliability of the fluorescence-quenching cLFIA method was evaluated through analysis of the OTA-spiked red grape wine and juice samples. The average recoveries ranged from 88.0% to 110.0% in red grape wine and from 92.0% to 110.0% in grape juice. Meanwhile, less than a 10% coefficient variation indicated an acceptable precision of the cLFIA method. In summary, the new AgNP-based fluorescence-quenching cLFIA is a simple, rapid, sensitive, and accurate method for quantitative detection of OTA in grape juice and wine or other foodstuffs.

Silver nanoparticles induce hormesis in A549 human epithelial cells

Despite the gaps in our knowledge on the toxicity of silver nanoparticles (AgNPs), the application of these materials is fast expanding, from medicine, to food as well as the use in consumer products. It has been reported that prolonged exposure might make cells more resistant to AgNPs. This prompted us to investigate if AgNPs may give rise to a hormetic response. Two types of AgNPs were used, i.e. colloidal AgNPs and an AgNP powder. For both types of nanosilver it was found that a low dose pretreatment of A549 human epithelial cells with AgNPs induced protection against a toxic dose of AgNPs and acrolein. This protection was more pronounced after pretreatment with the colloidal AgNPs. Interestingly, the mechanism of the hormetic response appeared to differ from that of acrolein. Adaptation to acrolein is related to Nrf2 translocation, increased mRNA expression of γGCS, HO-1 and increased GSH levels and the increased GSH levels can explain the hormetic effect. The adaptive response to AgNPs was not related to an increase in mRNA expression of γGCS and GSH levels. Yet, HO-1 mRNA expression and Nrf2 immunoreactivity were enhanced, indicating that these processes might be involved. So, AgNPs induce adaptation, but in contrast to acrolein GSH plays no role.

Optical nanoprobes for biomedical applications: shining a light on upconverting and near-infrared emitting nanoparticles for imaging, thermal sensing, and photodynamic therapy

Shining a light on spectrally converting lanthanide (Ln³⁺)-doped nanoparticles: progress, trends, and challenges in Ln³⁺-nanoprobes for near-infrared bioimaging, nanothermometry, and photodynamic therapy.

Antimicrobial Nanostructures for Neurodegenerative Infections

Nanostructures have been widely involved in changes in the drug delivery system. Nanoparticles have unique physicochemical properties, e.g., ultrasmall size, large surface area, and the ability to target specific actions. Various nanomaterials, like Ag, ZnO, Cu/CuO, and Al₂O₃, have antimicrobial activity. Basically, six mechanisms are involved in the production of antimicrobial activity, i.e., (1) destruction of the peptidoglycan layer, (2) release of toxic metal ions, (3) alteration of cellular pH via proton efflux pumps, (4) generation of reactive oxygen species, (5) damage of nuclear materials, and (6) loss of ATP production. Nanomedicine contributes to various pharmaceutical applications, like diagnosis and treatment of various ailments including microbial diseases. Furthermore, nanostructured antimicrobial agents are also involved in the treatment of the neuroinfections associated with neurodegenerative disorders. This chapter focuses on the nanostructure and nanomedicine of antimicrobial agents and their prospects for the possible management of infections associated with neurodegenerative disorders.

Fluctuation Spectroscopy Analysis of Glucose Capped Gold Nanoparticles

In this work, we report the synthesis and biophysical studies carried out on a new kind of biocompatible and very stable gold nanoparticle (GNP) stabilized with glucose through a PEG linker (AuNP-PEG-Glu). The synthetic path was optimized to obtain nanoparticles of controlled sizes. ζ-potential and dynamic light scattering measurements allowed assessment of the nanodimension, dispersity, surface charge, and stability of our GNPs. Confocal microscopy demonstrated qualitatively that glucose molecules are successfully bonded to GNP surfaces. For our study, we selected nanoparticles with diameter in a range that maximizes the internalization efficiency in cells (40 nm). A detailed investigation about the biophysical proprieties of AuNP-PEG-Glu was carried out by means of fluorescence correlation spectroscopy (FCS) and orbital tracking techniques. This work gives new insights about the uptake mechanism of gold nanoparticles capped with glucose molecules.

Biosynthesis, Antibacterial Activity and Anticancer Effects Against Prostate Cancer (PC-3) Cells of Silver Nanoparticles Using Dimocarpus Longan Lour. Peel Extract

Metal nanoparticles, particularly silver nanoparticles (AgNPs), are developing more important roles as diagnostic and therapeutic agents for cancers with the improvement of eco-friendly synthesis methods. This study demonstrates the biosynthesis, antibacterial activity, and anticancer effects of silver nanoparticles using Dimocarpus Longan Lour. peel aqueous extract. The AgNPs were characterized by UV-vis absorption spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscope (FTIR). The bactericidal properties of the synthesized AgNPs were observed via the agar dilution method and the growth inhibition test. The cytotoxicity effect was explored on human prostate cancer PC-3 cells in vitro by trypan blue assay. The expressions of phosphorylated stat 3, bcl-2, survivin, and caspase-3 were examined by Western blot analysis. The longan peel extract acted as a strong reducing and stabilizing agent during the synthesis. Water-soluble AgNPs of size 9-32 nm was gathered with a face-centered cubic structure. The AgNPs had potent bactericidal activities against gram-positive and gram-negative bacteria with a dose-related effect. AgNPs also showed dose-dependent cytotoxicity against PC-3 cells through a decrease of stat 3, bcl-2, and survivin, as well as an increase in caspase-3. These findings confirm the bactericidal properties and explored a potential anticancer application of AgNPs for prostate cancer therapy. Further research should be focused on the comprehensive study of molecular mechanism and in vivo effects on the prostate cancer.

Engineering nanolayered particles for modular drug delivery

Layer-by-layer (LbL) based self-assembly of nanoparticles is an emerging and powerful method to develop multifunctional and tissue responsive nanomedicines for a broad range of diseases. This unique assembly technique is able to confer a high degree of modularity, versatility, and compositional heterogeneity to nanoparticles via the sequential deposition of alternately charged polyelectrolytes onto a colloidal template. LbL assembly can provide added functionality by directly incorporating a range of functional materials within the multilayers including nucleic acids, synthetic polymers, polypeptides, polysaccharides, and functional proteins. These materials can be used to generate hierarchically complex, heterogeneous thin films on an extensive range of both traditional and novel nanoscale colloidal templates, providing the opportunity to engineer highly precise systems capable of performing the numerous tasks required for systemic drug delivery. In this review, we will discuss the recent advancements towards the development of LbL nanoparticles for drug delivery and diagnostic applications, with a special emphasis on the incorporation of biostability, active targeting, desirable drug release kinetics, and combination therapies into LbL nanomaterials. In addition to these topics, we will touch upon the next steps for the translation of these systems towards the clinic.

Biosynthesis of nanoparticles of metals and metalloids by basidiomycetes. Preparation of gold nanoparticles by using purified fungal phenol oxidases

The work shows the ability of cultured Basidiomycetes of different taxonomic groups-Lentinus edodes, Pleurotus ostreatus, Ganoderma lucidum, and Grifola frondosa-to recover gold, silver, selenium, and silicon, to elemental state with nanoparticles formation. It examines the effect of these metal and metalloid compounds on the parameters of growth and accumulation of biomass; the optimal cultivation conditions and concentrations of the studied ion-containing compounds for recovery of nanoparticles have been identified. Using the techniques of transmission electron microscopy, dynamic light scattering, X-ray fluorescence and X-ray phase analysis, the degrees of oxidation of the bioreduced elements, the ζ-potential of colloidal solutions uniformity, size, shape, and location of the nanoparticles in the culture fluid, as well as on the surface and the inside of filamentous hyphae have been determined. The study has found the part played by homogeneous chromatographically pure fungal phenol-oxidizing enzymes (laccases, tyrosinases, and Mn-peroxidases) in the recovery mechanism with formation of electrostatically stabilized colloidal solutions. A hypothetical mechanism of gold(III) reduction from HAuCl₄ to gold(0) by phenol oxidases with gold nanoparticles formation of different shapes and sizes has been introduced.

Colorimetric determination of Timolol concentration based on localized surface plasmon resonance of silver nanoparticles

In this work, a rapid and simple colorimetric method based on the surface plasmon resonance of silver nanoparticles (AgNPs) was developed for the detection of the drug Timolol. The method used is based on the interaction of Timolol with the surface of the as-synthesized AgNPs, which promotes aggregation of the nanoparticles. This aggregation exploits the surface plasmon resonance through the electric dipole-dipole interaction and coupling among the agglomerated particles, hence bringing forth distinctive changes in the spectra as well as the color of colloidal silver. UV-vis spectrophotometery was used to monitor the changes of the localized surface plasmon resonance of AgNPs at wavelengths of 400 and 550 nm. The developed colorimetric sensor has a wide dynamic range of 1.0 × 10(-7) M-1.0 × 10(-3) M for detection of Timolol with a low detection limit of 1.2 × 10(-6) M. The proposed method was successfully applied for the determination of Timolol concentration in ophthalmic eye-drop solution with a response time lower than 40 s.

Persistent Luminescent Nanocarrier as an Accurate Tracker in Vivo for Near Infrared-Remote Selectively Triggered Photothermal Therapy

Optical imaging-guidance of indocyanine green (ICG) for photothermal therapy (PTT) has great latent capacity in cancer therapy. However, the conventional optical image-guidance mode has caused strong tissue autofluorescence of the living tissue, which leads to the accurate infrared light irradiation cannot be conducted. In this article, ICG and persistent luminescence phosphors (PLPs) coloaded mesoporous silica nanocarriers ((ICG+PLPs)@mSiO2) were first designed and prepared for persistent luminescent imaging-guided PTT. The (ICG+PLPs)@mSiO2 nanocarriers could significantly improve signal-to-noise ratio during luminescence imaging-guided PTT, making the PLP promising for improving the accuracy of the tumor site for photothermal therapy in vivo. This paper is likely to develop a new way for accurately regulating cancer cell death based on luminescence imaging-guided PTT selectively triggered by near-infrared (NIR)-remote.

Selection and Identification of Molecular Gold Clusters at the Nano(gram) Scale: Reversed Phase HPLC-ESI-MS of a Mixture of Au-Peth MPCs

Recent advances in cluster synthesis make it possible to produce an enormous variety molecule-like MPCs of size, composition, shape, and surface-chemical combinations. In contrast to the significant growth in the synthetic capability to generate these materials, progress in establishing the physicochemical basis for their observed properties has remained limited. The main reason for this has been the lack of the analytical capability to generate and measure samples of suitably high (molecular) purity; such capability is also essential to support therapeutic and diagnostic MPC development. In order for MPC products to get to market, especially those products that are medical-field related, characterization is required to identify and quantify all components present in a material mixture. Here, we show results from analysis of several synthetic mixtures of gold MPCs by nonaqueous reversed-phase chromatography coupled with mass spectrometry detection. The additional or hidden components, revealed to be present in these mixtures, provide novel insights into their comparative stability and interactions.

In vitro biomechanical properties, fluorescence imaging, surface-enhanced Raman spectroscopy, and photothermal therapy evaluation of luminescent functionalized CaMoO4:Eu@Au hybrid nanorods on human lung adenocarcinoma epithelial cells

Highly dispersible Eu3+-doped CaMoO4@Au-nanorod hybrid nanoparticles (HNPs) exhibit optical properties, such as plasmon resonances in the near-infrared region at 790 nm and luminescence at 615 nm, offering multimodal capabilities: fluorescence imaging, surface-enhanced Raman spectroscopy (SERS) detection and photothermal therapy (PTT). HNPs were conjugated with a Raman reporter (4-mercaptobenzoic acid), showing a desired SERS signal (enhancement factor 5.0 × 105). The HNPs have a heat conversion efficiency of 25.6%, and a hyperthermia temperature of 42°C could be achieved by adjusting either concentration of HNPs, or laser power, or irradiation time. HNPs were modified with antibody specific to cancer biomarker epidermal growth factor receptor, then applied to human lung cancer (A549) and mouse hepatocyte cells (AML12), and in vitro PTT effect was studied. In addition, the biomechanical properties of A549 cells were quantified using atomic force microscopy. This study shows the potential applications of these HNPs in fluorescence imaging, SERS detection, and PTT with good photostability and biocompatibility.

Polyvinyl pyrrolidone-coated silver nanoparticles in a human lung cancer cells: time- and dose-dependent influence over p53 and caspase-3 protein expression and epigenetic effects

The present study was aimed at providing a better understanding of the influence of silver nanoparticles (AgNPs) on the p53 tumor suppressor protein. Cell line A549 was exposed to a range of concentrations of AgNPs, and a time course (up to 72 h) of cell viability was determined. We also determined the time course of gene and protein expression of p53, p21, murine double minute 2 (MDM2) and caspase-3. The expression of all of these proteins was also determined after daily exposure of the cells to 10 µg/mL of AgNPs for 7 days, or after discontinuous exposure by treating the cells every 3 days, for 15 or 30 days. Moreover, epigenetic changes in the acetylation of the histone H3 protein and in global DNA methylation patterns were determined after 72 h of exposure. Results showed that daily exposure to low doses of AgNPs, or a single exposure to high concentrations for 72 h, decreased gene and protein expression of p53, p21, MDM2 and caspase-3 in A549 cells. In contrast, a discontinuous exposure to low doses or a single exposure to low concentrations for 72 h increased the levels of the active forms of p53 and caspase-3, as well as the p21 and MDM2 protein levels. In addition, exposure to high concentrations of AgNPs for 72 h induced higher levels of global DNA methylation and global histone H3 deacetylation in A549 cells. These results provide new information on the toxic action of AgNPs.

Effects of green-synthesized silver nanoparticles on lung cancer cells in vitro and grown as xenograft tumors in vivo

Silver nanoparticles (AgNPs) have now been recognized as promising therapeutic molecules and are extending their use in cancer diagnosis and therapy. This study demonstrates for the first time the antitumor activity of green-synthesized AgNPs against lung cancer in vitro and in vivo. Cytotoxicity effect was explored on human lung cancer H1299 cells in vitro by MTT and trypan blue assays. Apoptosis was measured by morphological assessment, and nuclear factor-κB (NF-κB) transcriptional activity was determined by a luciferase reporter gene assay. The expressions of phosphorylated stat3, bcl-2, survivin, and caspase-3 were examined by Western blot analysis. AgNPs showed dose-dependent cytotoxicity and stimulation of apoptosis in H1299 cells. The effects on H1299 cells correlated well with the inhibition of NF-κB activity, a decrease in bcl-2, and an increase in caspase-3 and survivin expression. AgNPs significantly suppressed the H1299 tumor growth in a xenograft severe combined immunodeficient (SCID) mouse model. The results demonstrate the anticancer activities of AgNPs, suggesting that they may act as potential beneficial molecules in lung cancer chemoprevention and chemotherapy, especially for early-stage intervention.

Simultaneous Determination of Size and Quantification of Gold Nanoparticles by Direct Coupling Thin layer Chromatography with Catalyzed Luminol Chemiluminescence

The increasing use of metal-based nanoparticle products has raised concerns in particular for the aquatic environment and thus the quantification of such nanomaterials released from products should be determined to assess their environmental risks. In this study, a simple, rapid and sensitive method for the determination of size and mass concentration of gold nanoparticles (AuNPs) in aqueous suspension was established by direct coupling of thin layer chromatography (TLC) with catalyzed luminol-H2O2 chemiluminescence (CL) detection. For this purpose, a moving stage was constructed to scan the chemiluminescence signal from TLC separated AuNPs. The proposed TLC-CL method allows the quantification of differently sized AuNPs (13 nm, 41 nm and 100 nm) contained in a mixture. Various experimental parameters affecting the characterization of AuNPs, such as the concentration of H2O2, the concentration and pH of the luminol solution, and the size of the spectrometer aperture were investigated. Under optimal conditions, the detection limits for AuNP size fractions of 13 nm, 41 nm and 100 nm were 38.4 μg L(-1), 35.9 μg L(-1) and 39.6 μg L(-1), with repeatabilities (RSD, n = 7) of 7.3%, 6.9% and 8.1% respectively for 10 mg L(-1) samples. The proposed method was successfully applied to the characterization of AuNP size and concentration in aqueous test samples.

Laminin Receptor-Avid Nanotherapeutic EGCg-AuNPs as a Potential Alternative Therapeutic Approach to Prevent Restenosis

In our efforts to develop new approaches to treat and prevent human vascular diseases, we report herein our results on the proliferation and migration of human smooth muscles cells (SMCs) and endothelial cells (ECs) using epigallocatechin-3-gallate conjugated gold nanoparticles (EGCg-AuNPs) as possible alternatives to drug coated stents. Detailed in vitro stability studies of EGCg-AuNPs in various biological fluids, affinity and selectivity towards SMCs and ECs have been investigated. The EGCg-AuNPs showed selective inhibitory efficacy toward the migration of SMCs. However, the endothelial cells remained unaffected under similar experimental conditions. The cellular internalization studies have indicated that EGCg-AuNPs internalize into the SMCs and ECs within short periods of time through laminin receptor mediated endocytosis mode. Favorable toxicity profiles and selective affinity toward SMCs and ECs suggest that EGCg-AuNPs may provide attractive alternatives to drug coated stents and therefore offer new therapeutic approaches in treating cardiovascular diseases.

Current development of targeted oligonucleotide-based cancer therapies: Perspective on HER2-positive breast cancer treatment

This Review discusses the various types of non-coding oligonucleotides, which have garnered extensive interest as new alternatives for targeted cancer therapies over small molecule inhibitors and monoclonal antibodies. These oligonucleotides can target any hallmark of cancer, no longer limited to so-called "druggable" targets. Thus, any identified gene that plays a key role in cancer progression or drug resistance can be exploited with oligonucleotides. Among them, small-interfering RNAs (siRNAs) are frequently utilized for gene silencing due to the robust and well established mechanism of RNA interference. Despite promising advantages, clinical translation of siRNAs is hindered by the lack of effective delivery platforms. This Review provides general criteria and consideration of nanoparticle development for systemic siRNA delivery. Different classes of nanoparticle candidates for siRNA delivery are discussed, and the progress in clinical trials for systemic cancer treatment is reviewed. Lastly, this Review presents HER2 (human epidermal growth factor receptor type 2)-positive breast cancer as one example that could benefit significantly from siRNA technology. How siRNA-based therapeutics can overcome cancer resistance to such therapies is discussed.

Microwave-assisted ultrafast synthesis of silver nanoparticles for detection of Hg²⁺

Silver nanoparticles (AgNPs) were successfully prepared in aqueous solution by a one-pot procedure based on a rapid microwave-assisted green approach. L-Cysteine acted as a capping agent in the process of AgNP formation. The structural and morphological characteristics of the L-cysteine-capped AgNPs were investigated by the UV-vis, CD, FL, FTIR, XRD, TEM and EDX analysis. It was found that the well-dispersed crystalline AgNPs were formed after irradiation for 90 s and had sphere-like morphology. Such strategy may facilitate new ways to the synthesis of other metal nanoparticles, such as Au, Pt and Pd. In addition, the synthesized AgNPs were developed as a platform for the detection of Hg(2+) and showed a high sensitivity on the order of 1×10(-8) M. This sensing system could discriminate Hg(2+) from a wide range of cations (Ca(2+), Ba(2+), Mn(2+), etc.). The selectivity and sensitivity of AgNPs indicated its potential use as a sensor for Hg(2+) detection in the ecosystems.

Raman and DFT study of methimazole chemisorbed on gold colloidal nanoparticles

The SERS/DFT study of methimazole chemisorbed on Au nanoparticles paves the way for the use of these nanohybrids in biomedicine.

Drosophila melanogaster as a suitable in vivo model to determine potential side effects of nanomaterials: A review

Despite being a relatively new field, nanoscience has been in the forefront among many scientific areas. Nanoparticle materials (NM) present interesting physicochemical characteristics not necessarily found in their bulky forms, and alterations in their size or coating markedly modify their physical, chemical, and biological properties. Due to these novel properties there is a general trend to exploit these NM in several fields of science, particularly in medicine and industry. The increased presence of NM in the environment warrants evaluation of potential harmful effects in order to protect both environment and human exposed populations. Although in vitro approaches are commonly used to determine potential adverse effects of NM, in vivo studies generate data expected to be more relevant for risk assessment. As an in vivo model Drosophila melanogaster was previously found to possess reliable utility in determining the biological effects of NM, and thus its usage increased markedly over the last few years. The aims of this review are to present a comprehensive overview of all apparent studies carried out with NM and Drosophila, to attain a clear and comprehensive picture of the potential risk of NM exposure to health, and to demonstrate the advantages of using Drosophila in nanotoxicological investigations.

SERS Detection of Dopamine Using Label-Free Acridine Red as Molecular Probe in Reduced Graphene Oxide/Silver Nanotriangle Sol Substrate

The reduced graphene oxide/silver nanotriangle (rGO/AgNT) composite sol was prepared by the reduction of silver ions with sodium borohydride in the presence of H2O2 and sodium citrate. In the nanosol substrate, the molecular probe of acridine red (AR) exhibited a weak surface-enhanced Raman scattering (SERS) peak at 1506 cm(-1) due to its interaction with the rGO of rGO/AgNT. Upon addition of dopamine (DA), the competitive adsorption between DA and AR with the rGO took place, and the AR molecules were adsorbed on the AgNT aggregates with a strong SERS peak at 1506 cm(-1) that caused the SERS peak increase. The increased SERS intensity is linear to the DA concentration in the range of 2.5-500 μmol/L. This new analytical system was investigated by SERS, fluorescence, absorption, transmission electron microscope (TEM), and scanning electron microscope (SEM) techniques, and a SERS quantitative analysis method for DA was established, using AR as a label-free molecular probe.

Plant Extract (Bupleurum falcatum) as a Green Factory for Biofabrication of Gold Nanoparticles

This work describes a biofabrication process for gold nanoparticles in which the plant extract ( Bupleurum falcatum) is used as a reducing agent to convert gold ions to gold nanoparticles. Biofabricated gold nanoparticles with spherical shapes were observed with an average diameter of 10.5 ± 2.3 nm. The color of the gold nanoparticles was purple, with a surface plasmon resonance peak at 542 nm. The face-centered cubic structure of crystalline gold was confirmed by high-resolution X-ray diffraction patterns. The biofabricated gold nanoparticles demonstrated excellent catalytic activity towards the 4-nitrophenol reduction reaction. The current report suggests that plant extracts are valuable natural sources for the biofabrication of gold nanoparticles with excellent catalytic activities.

Nanoscale materials for hyperthermal theranostics

Recently, the use of nanoscale materials has attracted considerable attention with the aim of designing personalized therapeutic approaches that can enhance both spatial and temporal control over drug release, permeability, and uptake. Potential benefits to patients include the reduction of overall drug dosages, enabling the parallel delivery of different pharmaceuticals, and the possibility of enabling additional functionalities such as hyperthermia or deep-tissue imaging (LIF, PET, etc.) that complement and extend the efficacy of traditional chemotherapy and surgery. This mini-review is focused on an emerging class of nanometer-scale materials that can be used both to heat malignant tissue to reduce angiogenesis and DNA-repair while simultaneously offering complementary imaging capabilities based on radioemission, optical fluorescence, magnetic resonance, and photoacoustic methods.

Surface plasmon enhanced energy transfer between gold nanorods and fluorophores: application to endocytosis study and RNA detection

Previously we have demonstrated surface plasmon enhanced energy transfer between fluorophores and gold nanorods under two-photon excitation using fluorescence lifetime imaging microscopy (FLIM) in both solution and intracellular phases. These studies demonstrated that gold nanoparticle-dye energy transfer combinations are appealing, not only in Förster resonance energy transfer (FRET) imaging, but also energy transfer-based fluorescence lifetime sensing of bio-analytes. Here, we apply this approach to study the internalization of gold nanorods (GNRs) in HeLa cells using the early endosome labeling marker GFP. The observed energy transfer between GFP and the GNRs indicates the involvement of endocytosis in GNR uptake. Moreover, a novel nanoprobe based on oligonucleotide functionalized gold nanorods for nucleic acid sensing via dye-GNRs energy transfer is demonstrated, potentially opening up new possibilities in cancer diagnosis and prognosis. The influence of oligonucleotide design on such nanoprobe performance was studied for the first time using time-resolved fluorescence spectroscopy, bringing new insights to the optimization of the nanoprobe.

Highly efficient in vitro biosynthesis of silver nanoparticles using Lysinibacillus sphaericus MR-1 and their characterization

Silver nanoparticles (AgNPs) have been widely used in diverse fields due to their superior properties. Currently the biosynthesis of AgNPs is in the limelight of modern nanotechnology because of its green properties. However, relatively low yield and inefficiency diminish the prospect of applying these biosynthesized AgNPs. In this work, a rapid mass AgNP biosynthesis method using the cell-free extract of a novel bacterial strain, Lysinibacillus sphaericus MR-1, which has been isolated from a chemical fertilizer plant, is reported. In addition, the optimum synthesis conditions of AgNPs were investigated. The optimum pH, temperature, dosage, and reaction time were 12, 70 °C, 20 mM AgNO₃, and 75 min, respectively. Finally, AgNPs were characterized by optical absorption spectroscopy, zeta potential and size distribution analysis, x-ray diffraction, electron microscopy, and energy-dispersive x-ray spectroscopy. The results revealed that these biosynthesized AgNPs were bimolecular covered, stable, well-dispersed face centered cubic (fcc) spherical crystalline particles with diameters in the range 5-20 nm. The advantages of this approach are its simplicity, high efficiency, and eco-friendly and cost-effective features.

Scaling of optical forces on Au–PEG core–shell nanoparticles

Optical trapping of hybrid core–shell gold–polymer particles is studied.

Silver nanoparticles: synthesis, properties, and therapeutic applications

Silver nanoparticles (AgNPs) have been widely used in biomedical fields because of their intrinsic therapeutic properties. Here, we introduce methods of synthesizing AgNPs and discuss their physicochemical, localized surface plasmon resonance (LSPR) and toxicity properties. We also review the impact of AgNPs on human health and the environment along with the underlying mechanisms. More importantly, we highlight the newly emerging applications of AgNPs as antiviral agents, photosensitizers and/or radiosensitizers, and anticancer therapeutic agents in the treatment of leukemia, breast cancer, hepatocellular carcinoma, lung cancer, and skin and/or oral carcinoma.

Surface-enhanced Raman spectroscopy of the endothelial cell membrane

We applied surface-enhanced Raman spectroscopy (SERS) to cationic gold-labeled endothelial cells to derive SERS-enhanced spectra of the bimolecular makeup of the plasma membrane. A two-step protocol with cationic charged gold nanoparticles followed by silver-intensification to generate silver nanoparticles on the cell surface was employed. This protocol of post-labelling silver-intensification facilitates the collection of SERS-enhanced spectra from the cell membrane without contribution from conjugated antibodies or other molecules. This approach generated a 100-fold SERS-enhancement of the spectral signal. The SERS spectra exhibited many vibrational peaks that can be assigned to components of the cell membrane. We were able to carry out spectral mapping using some of the enhanced wavenumbers. Significantly, the spectral maps suggest the distribution of some membrane components are was not evenly distributed over the cells plasma membrane. These results provide some possible evidence for the existence of lipid rafts in the plasma membrane and show that SERS has great potential for the study and characterization of cell surfaces.