Cisplatin-tethered gold nanoparticles that exhibit enhanced reproducibility, drug loading, and stability: a step closer to pharmaceutical approval?

Gold nanoparticles (AuNPs) can be used as delivery vehicles for platinum anticancer drugs, improving their targeting and uptake into cells. Here, we examine the appropriateness of different-sized AuNPs as components of platinum-based drug-delivery systems, investigating their controlled synthesis, reproducibility, consistency of drug loading, and stability. The active component of cisplatin was tethered to 25, 55, and 90 nm AuNPs, with the nanoparticles being almost spherical in nature and demonstrating good batch-to-batch reproducibility (24.37 ± 0.62, 55.2 ± 1.75, and 89.1 ± 2.32 nm). The size distribution of 25 nm AuNPs has been significantly improved, compared with a previous method that produces polydispersed nanoparticles. Attachment of platinum to the AuNP surface through a poly(ethylene glycol) (PEG) linker exhibits an increase in the drug loading with increasing particle size: 25 nm (815 ± 106 drug molecules per AuNP), 55 nm (14216 ± 880), and 90 nm (54487 ± 15996). The stability of the naked, PEGylated, and platinum-conjugated nanoparticles has been examined over time under various conditions. When stored at 4 °C, there is minimal variation in the diameter for all three AuNP sizes; variation after 28 days for the 25 nm AuNPs was 2.4%; 55 nm, 3.3%; and 90 nm, 3.6%. The 25 nm AuNPs also demonstrate minimal changes in UV-visible absorbance over the same time period.     

Visible‐Light‐Triggered Drug Release from TiO2 Nanotube Arrays: A Controllable Antibacterial Platform

In this work, we use a double‐layered stack of TiO₂ nanotubes (TiNTs) to construct a visible‐light‐triggered drug delivery system. The key for visible light drug release is a hydrophobic cap on the nanotubes containing Au nanoparticles (AuNPs). The AuNPs allow for a photocatalytic scission of the hydrophobic chain under visible light. To demonstrate this principle, we loaded ampicillin (AMP) into the lower part of the TiO₂ nanotube stack, triggered visible‐light‐induced release, and carried out antibacterial studies. The release from the platform becomes most controllable if the drug is silane‐grafted in the hydrophilic bottom layer for drug storage. Thus, visible light photocatalysis can also determine the release kinetics of the active drug from the nanotube wall.     

Gold‐Aryl nanoparticles coated with polyelectrolytes for adsorption and protection of DNA against nuclease degradation

Binding DNA on nanoparticles was pursued to form nanoplatform for formation of non‐viral gene system. Carboxyl derivatized gold‐aryl nanoparticles can bind with biodegradable cationic polyelectrolytes such as polydiallyldimethylammonium chloride (PDADMAC). In our study, we used gold‐aryl nanoparticles (AuNPs) treated with PDADMAC to form conjugates with non‐thiol or non‐disulfide modified oligonucleotide DNA. Both AuNPs‐DNA and PDADMAC‐AuNPs‐DNA biomaterials were characterized using UV–Vis, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM) and agarose gel electrophoresis. UV–Vis showed a red shift in the plasmon peak as compared with unconjugated AuNPs. DLS measurements also showed difference in the size of AuNPs‐DNA and PDADMAC‐AuNPs‐DNA. AFM and TEM results showed proper conjugation of DNA with AuNPs. Gel electrophoresis proved the presence of interaction between PDADMAC‐AuNPs and negatively charged DNA. The binding of DNA in the described bioconjugate enhanced its protection against nuclease degradation and prolonged its presence in the digestive environment of DNase‐I. From the results we expect that these biomaterials can be used in nanomedicine with emphasis on non‐viral gene system.     

Fabrication of Xanthan stabilized green gold nanoparticles based tolbutamide delivery system for enhanced insulin secretion in mice pancreatic islets

Abstract

Tolbutamide is an oral anti-diabetic agent for the treatment of type 2 diabetic patients. Its lower absorption results in its inferior therapeutic efficacy. Nano-carrier systems have the subject of greater interests for enhancing efficacy of such drugs. Current study was designed to improve the tolbutamide therapeutic efficacy through its delivery in Gum Xanthan (GX) stabilized green gold nanoparticles (AuNPs). GX stabilized AuNPs were characterized for surface plasmon resonance (SPR), morphology, size, polydisoersity index (PDI) and zeta potential through UV spectrophotometer, atomic force microscope (AFM) and zetasizer respectively. They were used for loading tolbutamide and loaded nanoparticles were investigated for morphology, size, PDI, zeta potential and drug loading efficiency. FT-IR analysis was used for conforming GX functional groups involvement in AuNPs stabilization and drug-excepients interactions. Tolbutamide loaded in the synthesized nanoparticles was investigated for its insulin secretion potentials in isolated mice islets. Synthesized AuNPs were found in nano-size range with spherical morphology, increased surface negativity and loaded increased concentration of drug without changing its chemical nature. They markedly enhanced the tolbutamide insulin secretion potentials as compared to simple drug solution. Results confirm that the developed nano-carrier system is highly efficient in achieving higher therapeutic efficacy of drugs like tolbutamide.     

Dimerization of Organic Dyes on Luminescent Gold Nanoparticles for Ratiometric pH Sensing

Synergistic effects arising from the conjugation of organic dyes onto non‐luminescent metal nanoparticles (NPs) have greatly broadened their applications in both imaging and sensing. Herein, we report that conjugation of a well‐known pH‐insensitive dye, tetramethyl‐rhodamine (TAMRA), to pH‐insensitive luminescent gold nanoparticles (AuNPs) can lead to an ultrasmall nanoindicator that can fluorescently report local pH in a ratiometric way. Such synergy originated from the dimerization of TAMRA on AuNPs, of which geometry was very sensitive to surface charges of the AuNPs and can be reversely modulated through protonation of surrounding glutathione ligands. Not limited to pH‐insensitive dyes, this pH‐dependent dimerization can also enhance the pH sensitivity of fluorescein, a well‐known pH‐sensitive dye, within a larger pH range, opening up a new pathway to design ultrasmall fluorescent ratiometric nanoindicators with tunable wavelengths and pH response ranges.     

A Simple Model to Estimate the Number of Metal Engineered Nanoparticles in Samples Using Inductively Coupled Plasma Optical Emission Spectrometry

Accurate determination of the size and the number of nanoparticles plays an important role in many different environmental studies of nanomaterials, such as fate, toxicity, and occurrence in general. This work presents an accurate model that estimates the number of nanoparticles from the mass and molar concentration of gold nanoparticles (AuNPs) in water. Citrate-capped AuNPs were synthesized and characterized using transmission electron microscopy (TEM) and ultraviolet–visible spectroscopy (UV-vis). A mimic of environmental matrices was achieved by spiking sediments with AuNPs, extracted with leachate, and separated from the bulk matrix using centrifuge and phase transfer separation techniques. The quantification of AuNPs’ molar concentration on the extracted residues was achieved by inductively coupled plasma optical emission spectroscopy (ICP-OES). The molar concentrations, an average diameter of 27 nm, and the colloidal suspension volumes of AuNPs enable the calculation of the number of nanoparticles in separated residues. The plot of the number of AuNPs against the mass of AuNPs yielded a simple linear model that was used to estimate the number of nanoparticles in the sample using ICP-OES. According to the authors’ knowledge, this is the first adaptation of the gravimetric method to ICP-OES for estimating the number of nanoparticles after separation with phase transfer.     

Rapid synthesis of bovine serum albumin-conjugated gold nanoparticles using pulsed laser ablation and their anticancer activity on hela cells

Nanoscience research aims to produce nanoparticles without adverse effects for medical applications. The pulsed laser ablation (PLA) technique was utilized in this study to synthesize gold nanoparticles (AuNPs) using bovine serum albumin (BSA) in simulated body fluid (SBF) at the fundamental wavelength of the Nd: YAG laser (1064 nm). BSA acted as a stabilizer, reducing and capping agent to produce spherically shaped AuNPs (diameter 3–10 nm). The successful synthesis of AuNPs was confirmed through color changes and UV–vis spectroscopy. The agglomeration and precipitation of AuNPs are attributed to the presence of BSA in the solution, and electrostatic repulsion interactions between BSA and Au nanoclusters. The effect of salt concentration of SBF on BSA stability as well as the interaction of BSA conjugated AuNPs to form complexes was studied using molecular dynamic simulations. Our results show that the stability of AuNPs-BSA conjugates increase with the salt concentration of BSA. Moreover, the synthesized AuNPs exhibit low toxicity and high biocompatibility, supporting their application in drug delivery. Investigation of the cytotoxic effect of the synthesized AuNPs show that normal fibroblast cells (L929) remain intact after treatment whereas a dose-dependent inhibition effect on the growth of cervix cancer cells (HeLa) is observed. In general, this study presents an effective, environmentally-friendly, and facile approach to the synthesis of multifunctional AuNPs using the PLA technique, as a promising efficacious therapeutic treatment of cervical cancer.     

Tuning the In Vivo Transport of Anticancer Drugs Using Renal‐Clearable Gold Nanoparticles

Precise control of in vivo transport of anticancer drugs in normal and cancerous tissues with engineered nanoparticles is key to the future success of cancer nanomedicines in clinics. This requires a fundamental understanding of how engineered nanoparticles impact the targeting‐clearance and permeation‐retention paradoxes in the anticancer‐drug delivery. Herein, we systematically investigated how renal‐clearable gold nanoparticles (AuNPs) affect the permeation, distribution, and retention of the anticancer drug doxorubicin in both cancerous and normal tissues. Renal‐clearable AuNPs retain the advantages of the free drug, including rapid tumor targeting and high tumor vascular permeability. The renal‐clearable AuNPs also accelerated body clearance of off‐target drug via renal elimination. These results clearly indicate that diverse in vivo transport behaviors of engineered nanoparticles can be used to reconcile long‐standing paradoxes in the anticancer drug delivery.     

Mesoporous silica nanoparticles for 19F magnetic resonance imaging,fluorescence imaging,and drug delivery

Multifunctional mesoporous silica nanoparticles (MSNs) are good candidates for multimodal applications in drug delivery, bioimaging, and cell targeting. In particular, controlled release of drugs from MSN pores constitutes one of the superior features of MSNs. In this study, a novel drug delivery carrier based on MSNs, which encapsulated highly sensitive ¹⁹F magnetic resonance imaging (MRI) contrast agents inside MSNs, was developed. The nanoparticles were labeled with fluorescent dyes and functionalized with small molecule-based ligands for active targeting. This drug delivery system facilitated the monitoring of the biodistribution of the drug carrier by dual modal imaging (NIR/¹⁹F MRI). Furthermore, we demonstrated targeted drug delivery and cellular imaging by the conjugation of nanoparticles with folic acid. An anticancer drug (doxorubicin, DOX) was loaded in the pores of folate-functionalized MSNs for intracellular drug delivery. The release rates of DOX from the nanoparticles increased under acidic conditions, and were favorable for controlled drug release to cancer cells. Our results suggested that MSNs may serve as promising ¹⁹F MRI-traceable drug carriers for application in cancer therapy and bio-imaging.     

Formulation of gold nanoparticles with hibiscus and curcumin extracts induced anti-cancer activity

Gold nanoparticles (AuNPs) have shown a potential for biological applications due to their biocompatibility and high efficiency in drug delivery. Most of the times, the chemical routs are being used to synthesize the AuNPs products. In this paper, eco-friendly non-chemical rout was used to prepare AuNPs by utilizing hibiscus and curcumin extracts as reducing and stabilizing agents, and subsequently their anticancer activities were investigated. The synthesized AuNPs were characterized by using ultraviolet–visible spectroscopy (UV–Vis spectroscopy), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). UV–Vis spectroscopy analysis confirmed the characteristics absorption peak of gold, and FTIR findings were highlighted the characteristics boding. SEM and TEM analyses showed that the particles were predominantly spherical in shape. The particles were well dispersed when they were prepared under Hibiscus extracts with average size ～ 13 nm. An interesting morphology was observed when AuNPs were prepared with curcumin, where particles displayed an interconnected morphology (average size ～ 18 nm). The anticancer cell activity of AuNPs was studied against human colorectal carcinoma cells (HCT-116) and breast cancer cells (Michigan Cancer Foundation-7 (MCF-7)). The results of anticancer study showed that the treatment of cancer cells with AuNPs decreased the number of cells significantly as compared to control cells. The AuNPs -Hibiscus specimen showed a better inhibiting property than AuNPs -Curcumin, which is attributed to their uniform dispersion and small size.     

Green synthesis and chemical characterization of Thymus vulgaris leaf aqueous extract conjugated gold nanoparticles for the treatment of acute myeloid leukemia in comparison to doxorubicin in a leukemic mouse model

Recently, metallic nanoparticles have been used for the treatment of several disorders, such as cancer. Indeed, finding the chemotherapeutic drug of nanoparticles is in researching the priority of both developed and developing countries. The present study confirms the ability of aqueous extract of Thymus vulgaris grown under in vitro condition for the biosynthesis of gold nanoparticles (AuNPs). Also, in this study, we indicated the antioxidant, cytotoxicity, and anti-acute myeloid leukemia properties of AuNPs compared to doxorubicin in a leukemic mouse model. The synthesized AuNPs were characterized using different techniques including X-ray diffraction (XRD), energy Dispersive X-ray Spectrometry (EDS), fourier-transform infrared spectroscopy (FT-IR) spectroscopy, ultraviolet–visible spectroscopy (UV–Vis.), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). In vivo design, induction of acute myeloid leukemia was done by 7,12-Dimethylbenz[a]anthracene (DMBA) in 75 mice. Then, the animals were randomly divided into six subgroups, including control, untreated, doxorubicin, AuNPs, T. vulgaris, and HAuCl₄. By quantitative real-time PCR, sphingosine-1-phosphate receptor-1 and sphingosine-1-phosphate receptor-5 mRNA expression in lymphocytes were significantly (P ≤ 0.01) raised by treating the leukemic mice with the AuNPs and doxorubicin. Also, AuNPs similar to doxorubicin, significantly (P ≤ 0.01) enhanced the anti-inflammatory cytokines (IL4, IL5, IL10, IL13, and IFNα) and the platelet, lymphocyte, and red blood cell (RBC) parameters and reduced the pro-inflammatory cytokines (IL1, IL6, IL12, IL18, IFNY, and TNFα), and the total white blood cell (WBC), blast, monocyte, neutrophil, eosinophil, and basophil counts as compared to the untreated mice. In vitro design, 2,2-diphenyl-1-picrylhydrazyl (DPPH) test revealed similar antioxidant potentials for doxorubicin and AuNPs. Furthermore, AuNPs similar to doxorubicin had low cell viability dose-dependently against 32D-FLT3-ITD, Human HL-60/vcr, and Murine C1498 cell lines without any cytotoxicity on HUVEC cell line. Above results confirm the excellent antioxidant, cytotoxicity, and anti-acute myeloid leukemia effects of AuNPs compared to doxorubicin. After confirming these results in clinical trial studies, AuNPs can be used as a chemotherapeutic drug for the treatment of acute myeloid leukemia in human.     

Biofunctionalized silver and gold nanoparticles as potential curative agents

In this study, the bark of an important medicinal plant, Indigofera aspalathoides is utilized as a bioreductant for the synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs). The formation of nanoparticles was monitored, and the reaction parameters were optimized by UV–Vis spectroscopy. The attachment of biocomponents as stabilizer was proved employing Fourier‐transform infrared (FT‐IR) studies. Through transmission electron microscopy (TEM), the morphology was found to be predominantly spherical and a mixture of triangle and hexagon in the case of AgNPs and AuNPs, respectively. The crystallite size of AgNPs and AuNPs was affirmed through X‐ray diffraction (XRD) studies using Sherrer formula as 22.03 and 47.70 nm, respectively. DPPH method was adopted to analyse the free‐radical quenching ability, and the AgNPs, AuNPs and extract showed inhibition of 76%, 89% and 59% at a concentration of 200 μg ml^?1, and the corresponding IC₅₀ values were 86.49, 55.20 and 149.19 μg ml^?1. The binding of nanoparticles to calf‐thymus DNA (CT‐DNA) was through groove and the high binding constants (8.49 × 10⁶ M^?1 and 2.34 × 10⁷ M^?1 for AgNPs and AuNPs) point out the potential of these nanoparticles as curative drugs. The MTT assay showed that AgNPs were 100% toxic, and the low IC₅₀ value suggests that this can be used in the medicinal field as a safe drug.     

Effect of Pluronic P103 Concentration on the Simple Synthesis of Ag and Au Nanoparticles and Their Application in Anatase-TiO2 Decoration for Its Use in Photocatalysis

Silver and gold nanoparticles were synthesized under environmentally-friendly reaction conditions by using a biodegradable copolymer and water as a solvent. The triblock copolymer Pluronic P103 was utilized as a stabilizing agent or soft template to produce Ag and Au nanoparticles (NPs) of different sizes. Moreover, in the synthesis of Au NPs, the polymer acted as a reducing agent, decreasing the number of reagents used and consequently the residues produced, hence, rendering the procedure less complicated. It was observed that as the concentration of the polymer increased, the size of the metallic NPs augmented as well. However, AgNPs and AuNPs prepared with 1 and 10 wt% Pluronic P103, respectively, showed a significant decrease in particle size due to the presence of polymeric soft templates. The hybrid materials (metal/polymer) were characterized by UV-Vis spectroscopy, DLS, and TEM. The pre-synthesized nanoparticles were employed to decorate anatase-TiO₂, and the composites were characterized by DRS, XRD, BET surface area measurements, the TEM technique with the EDS spectrum, and XPS spectroscopy to demonstrate NPs superficial incorporation. Finally, methylene blue was used as a probe molecule to evidence the effect of NPs decoration in its photocatalytic degradation. The results showed that the presence of the NPs positively affected methylene blue degradation, achieving 96% and 97% removal by utilizing TAg0.1 and TAu10, respectively, in comparison to bare anatase-TiO₂ (77%).     

Effect of gold nanoparticles synthesized using the aqueous extract of Satureja hortensis leaf on enhancing the shelf life and removing Escherichia coli O157:H7 and Listeria monocytogenes in minced camel's meat: The role of nanotechnology in the food industry

Because herbal nanoparticles have antimicrobial properties, researchers have tried to synthesize them to aid in increasing the shelf time of food and food products. In this regard, gold nanoparticles (AuNPs) synthesized by plants are particularly important. In this study, fresh and clean leaves of Satureja hortensis were selected for the synthesis of AuNPs. We also evaluated the efficacy of these nanoparticles to increase the shelf life of and remove Escherichia coli O157:H7 and Listeria monocytogenes from minced camel's meat. The nanoparticles were analyzed by UV–visible spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction tests. The FT-IR spectroscopy results demonstrated that the antioxidant compounds in the plant were the sources of reducing power, reducing gold ions to AuNPs. FE-SEM and TEM images revealed the size of the nanoparticles to be 22.26 nm. The 2,2-diphenyl-1-picrylhydrazyl test revealed similar antioxidant potentials for S. hortensis, AuNPs, and butylated hydroxytoluene. S. hortensis and AuNPs had high cell viability dose-dependently against the human umbilical vein endothelial cell line. At the beginning of the food industry part of this experiment, all samples of control, S. hortensis, and AuNPs were preserved at 4°C for 20 days. During these 20 days, the sensory, chemical, and microbiological parameters were assessed for all samples. AuNPs significantly inhibited the growth of E. coli and L. monocytogenes. In addition, AuNPs significantly increased the protein carbonyl content, thiobarbituric acid reactive substances, pH, peroxide value, total volatile base nitrogen, and sensory attributes (color, odor, and overall acceptability). The best results were seen in AuNPs (1%). These findings reveal that the inclusion of S. hortensis extract improves the solubility of AuNPs, which led to a notable enhancement in their preservative and antibacterial effects.     

Effect of surface modification with various thiol compounds on colloidal stability of gold nanoparticles

Gold nanoparticles (AuNPs) are attractive materials due to their special optical and electronic properties. However, they tend to aggregate particularly in the presence of thiol‐containing compounds. In this study, to investigate the effect of surface conjugation with thiol‐containing compounds on colloidal stability, thiol compounds with various structures as modifying agents were used. To this end, AuNPs were synthesized and stabilized by trisodium citrate in aqueous solution, and then modified with thiol‐containing compounds, namely cysteamine hydrochloride (MEA, containing primary amine groups), 2‐mercaptoethanol (BME, containing hydroxyl groups), 1‐dodecanthiol (LCA, containing long‐chain alkyl groups) and thioglycolic acid (TGA, containing carboxylic acid groups). We studied the effect of thiol ligands on solution stability of colloidal AuNPs and on the formation of aggregates originating from the modification process using UV–visible spectroscopy, dynamic light scattering, field emission scanning electron microscopy and transmission electron microscopy. Results showed that surface modification with MEA, BME and LCA led to the formation of aggregates. However, conjugation with TGA showed a concentration‐dependent behaviour: surface modification with low concentration resulted in the formation of aggregates whereas that with high concentration of TGA did not disturb the colloidal stability of AuNPs. Finally, the effect of surface modification on temperature increase of solutions originating from infrared light irradiation was studied, where the temperature increase depends on the surface‐modifying compound.     

Chemical characterization and evaluation of antimicrobial and cutaneous wound healing potentials of gold nanoparticles using Allium saralicum R.M. Fritsch

The use of herbal medicines dates back a long way in history. Herbal medicines have been widely used all over the world since ancient times and have been recognized by physicians and patients for their good therapeutic value as they have fewer adverse effects than modern medicines. Recently, researchers have used gold nanoparticles synthesized by plants in the prevention, control, and treatment of infectious disorders and cutaneous wounds. The aims of this study were to synthesize gold nanoparticles from aqueous extract of Allium saralicum R.M. Fritsch (AuNPs) and assess their therapeutic capacities. The nanoparticles were characterized by UV–visible spectroscopy (UV–Vis), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR results offered polysaccharides and protein in A. saralicum were the sources of reducing power, reducing gold ions to AuNPs. According to XRD analysis, the crystal size of the nanoparticles was 41.6 nm. TEM and FE-SEM images exhibited average diameters of 45 nm for the biosynthesized nanoparticles. The synthesized AuNPs had great cell viability on HUVECs line and showed this method was nontoxic. The 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test indicated similar antioxidant potentials for A. saralicum, AuNPs, and butylated hydroxytoluene. To determine the antifungal and antibacterial properties of HAuCl₄, A. saralicum, and AuNPs, agar diffusion tests were used. The aim of the application both HAuCl₄ and A. saralicum in microbial tests was to investigate the synergism effects between them. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were specified by macro-broth dilution assay. AuNPs exhibited higher antifungal and antibacterial effects than all standard antibiotics (p ≤ 0.01). The MIC and MBC of AuNPs against all bacteria were in the ranges 1–4 mg/ml and 2–8 mg/ml, respectively. The MIC and MFC of AuNPs against all fungi were in the ranges 1–4 mg/ml and 2–4 mg/ml, respectively. In vivo part, AuNPs ointment group raised significantly (p ≤ 0.01) the wound contracture, vessel, hydroxyl proline, hexuronic acid, fibrocyte, fibroblast, and fibrocytes/fibroblast rate and decreased significantly (p ≤ 0.01) the wound area, total cells, and lymphocyte compared to other groups in rats. The results of FT-IR, UV–Vis, XRD, TEM, and FE-SEM analyses confirm that the aqueous extract of A. saralicum leaves can be used to yield gold nanoparticles with a notable amount of remedial effects without any cytotoxicity against HUVECs.     

Self-assembly of ionic liquid (BMI-PF6)-stabilized gold nanoparticles on a silicon surface: chemical and structural aspects

Ultrafine monodisperse gold nanoparticles (AuNPs) were synthesized by an elegant sputtering of gold onto 1- n-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF(6)) ionic liquid. It was found that the BMI-PF(6) supramolecular aggregates were loosely coordinated to the gold nanoparticles and were replaceable with thiol molecules. The self-assembly of BMI-PF(6)-stabilized AuNPs onto a (3-mercaptopropyl)trimethoxysilane (MPS)-functionalized silicon surface in 2D arrays, followed by dodecanethiol (DDT) treatment, have been demonstrated using X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and contact angle measurements. DDT treatment of tethered AuNPs revealed two types of interactions between AuNPs and the MPS-functionalized surface: (a) AuNPs anchor through Au-S chemisorption linkage resulting in strong immobilization and (b) some of the AuNPs are supported by physisorption, driven by BMI-PF(6). The attachment of these particles remains unchanged with sonication. The replacement of BMI-PF(6) aggregates from physisorbed AuNPs with DDT molecules advances the dilution of their interaction with the MPS-functionalized surface, and they subsequently detach from the silicon surface. The present finding is promising for the immobilization of ionic liquid-stabilized nanoparticles, which is very desirable for electronic and catalytic device fabrication. Additionally, these environmentally friendly AuNPs are expected to replace conventional citrate-stabilized AuNPs.     

Colloidal stability evolution and completely reversible aggregation of gold nanoparticles functionalized with rationally designed free radical initiators

A series of molecular adsorbates having various chain lengths of terminal poly(ethylene glycol methyl ether) (PEG) moieties, thiol head groups, and intervening free radical initiator moieties was used to functionalize the surface of gold nanoparticles (AuNPs). The bulky PEG groups stabilized the functionalized AuNPs by providing steric hindrance against AuNP aggregation, such aggregation being a major problem in the modification and manipulation of metal nanoparticles. UV–vis spectroscopy was used to evaluate the stability of the adsorbate-functionalized AuNPs as a function of AuNP size (～15, 40, and 90 nm in diameter) and PEG chain length (Mn 350, 750, and 2,000). The longer PEG chains (Mn 750 and 2,000) afforded stability to AuNPs with smaller gold cores (～15 and 40 nm in diameter) for up to several days without any marked aggregation. In contrast, the adsorbate-functionalized AuNPs with the largest gold cores (～90 nm) were noticeably less stable than those with the smaller gold cores. Importantly, the adsorbate-functionalized AuNPs could be isolated in solvent-free “dried” form and readily dispersed in aqueous buffer solution (both acidic and basic) and various organic solvents (protic and aprotic). This isolation–redispersion (i.e., aggregation/deaggregation) process was completely reversible. The chemisorption of the PEG-terminated initiator on the surface of the AuNPs was verified by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). As a whole, the strategy reported here affords colloidally stable, free radical initiator-functionalized AuNPs and offers a promising general method for encapsulating metal nanoparticles within polymer shells.

Facile preparation of Au nanoparticles mediated by Foeniculum Vulgare aqueous extract and investigation of the anti-human breast carcinoma effects

This experiment evaluated antioxidant, anti-human breast cancer activities, and cytotoxicity effects of green synthesis of Au nanoparticles (AuNPs) containing Foeniculum Vulgare aqueous extract. Mixing Foeniculum Vulgare aqueous with Au chloride solution produced Au nanoparticles. The characteristics of Au nanoparticles determined using Fourier Transformed Infrared Spectroscopy (FT‐IR), Transmission Electron Microscopy (TEM), UV–Visible Spectroscopy (UV–Vis), and Field Emission Scanning Electron Microscopy (FE‐SEM). To check the cytotoxicity and anti-breast cancer effects of Au chloride, Foeniculum Vulgare aqueous extract, and AuNPs on common breast cancer cell lines i.e., ZR-75-30, T47D, and HCC1187 was used MTT assay. AuNPs showed no cytotoxicity and the most effective anti-breast cancer features compared to other items that were tested. They had no cytotoxic effects on normal cell line (HUVEC) and had very low cell viability, high anti-breast cancer activities dose-dependently against ZR-75-30, T47D, and HCC1187 cell lines. In the presence of butylated hydroxytoluene as the positive control, the DPPH test was used to evaluate the antioxidant features of Au chloride, Foeniculum Vulgare aqueous extract, and Au nanoparticles. AuNPs showed the best antioxidant properties compared to other items that were tested. Perhaps remarkable anti-human breast cancer activities of Au nanoparticles synthesized by Foeniculum Vulgare aqueous extract due to its antioxidant properties. After clinical trial and confirmation of results, this formulation can be used as an effective drug to treat breast cancer.     

Gelatin-coated gold nanoparticles as an effective pH-sensitive methotrexate drug delivery system for breast cancer treatment

The present study investigates the synthesis and effectiveness of gold/gelatin nanoparticles (NPs) biopolymer as a carrier for methotrexate (MTX) drug. Two different shapes of gold particles, including spherical AuNPs (50 & 100 nm) and gold nanorods (AuNRs) with three different sizes (20, 50 and 100 nm length) were synthesized using the chemical reduction method. The effect of AuNPs size and shape on the entrapment efficiency (E.E), the release rate of the drug, and cellular uptake were investigated. The surfaces of both AuNPs and AuNRs were coated with a gelatin biopolymer, and the stability and property of the generated compounds were studied. Moreover, MTX as a chemotherapeutic agent was loaded on the gelatin-coated AuNPs/AuNRs complexes. The physicochemical properties of the gelatin-coated AuNPs/AuNRs complexes were studied using ultraviolet-visible (UV–Vis) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The E.E and MTX release behavior from the complexes at pH values of 7.4 and 5.4 and temperatures of 37 and 40 °C were investigated in vitro. The cytotoxic effects of AuNPs, AuNPs-Gelatin, AuNPs-Gelatin-MTX, AuNRs, AuNRs-Gelatin, AuNRs-Gelatin-MTX and free MTX were studied. The results indicated that the E.E of AuNPs was higher than that of AuNRs. The highest release rate of the drug was related to the AuNR1-gelatin complex (pH 5.4 and temperature of 40 °C). In addition, MTX loaded AuNR2-gelatin showed the highest cytotoxic effect on the MCF-7 breast cancer cell line so that even its cell cytotoxicity was more than that of the free drug.