Gold Nanoparticles as a Versatile Platform for Optimizing Physicochemical Parameters for Targeted Drug Delivery

Understanding nanoparticle-liver interactions in nanomedicine

INTRODUCTION

Understanding the interactions between administered nanoparticles and the liver is crucial for developing safe and effective nanomedicines. As the liver can sequester up to 99% of these particles due to its major phagocytic role, understanding these interactions is vital for clinical translation.

AREAS COVERED

This review highlights recent studies on nanoparticle-liver interactions, including the influence of nanoparticle physicochemical properties on delivery, strategies to enhance delivery efficiency by modulating liver Kupffer cells, and their potential for treating certain hepatic diseases. Additionally, we discuss how aging impacts the liver's phagocytic functions.

EXPERT OPINION

While liver accumulation can hinder nanomedicine safety and effectiveness, it also presents opportunities for treating certain liver diseases. A thorough understanding of nanoparticle-liver interactions is essential for advancing the clinical application of nanomedicines.

An application of carbohydrate polymers-based surface-modified gold nanoparticles for improved target delivery to liver cancer therapy - A systemic review

Gold nanoparticles have been broadly investigated as cancer diagnostic and therapeutic agents. Gold nanoparticles are a favorable drug delivery vehicle with their unique subcellular size and good biocompatibility. Chitosan, agarose, fucoidan, porphyran, carrageenan, ulvan and alginate are all examples of biologically active macromolecules. Since they are biocompatible, biodegradable, and irritant-free, they find extensive application in biomedical and macromolecules. The versatility of these compounds is enhanced because they are amenable to modification by functional groups like sulfation, acetylation, and carboxylation. In an eco-friendly preparation process, the biocompatibility and targeting of GNPs can be improved by functionalizing them with polysaccharides. This article provides an update on using carbohydrate-based GNPs in liver cancer treatment, imaging, and drug administration. Selective surface modification of several carbohydrate types and further biological uses of GNPs are focused on.

Nanoemulsion of Lavandula angustifolia Essential Oil/Gold Nanoparticles: Antibacterial Effect against Multidrug-Resistant Wound-Causing Bacteria

Hospitalized patients are severely impacted by delayed wound healing. Recently, there has been a growing focus on enhancing wound healing using suitable dressings. Lavandula angustifolia essential oil (LEO) showed potential antibacterial, anti-inflammatory, and wound healing properties. However, the prepared gold nanoparticles possessed multifunctional properties. Consequently, the present investigation aimed to synthesize a novel nanosystem consisting of nano-Lavandula angustifolia essential oil and gold nanoparticles prepared through ultrasonic nanoemulsifying techniques in order to promote wound healing and combat bacterial infection. LEO showed potent antibacterial activity against Klebsiella pneumoniae, MRSA and Staphylococcus aureus with minimum inhibitory concentration (MIC) values of 32, 16 and 16 µg/mL, respectively, while exhibiting low activity against Proteus mirabilis. Interestingly, the newly formulated nano-gold/nano-Lavandula angustifolia penetrated the preformed P. mirabilis biofilm with a full eradication of the microbial cells, with MIC and MBEC (minimal biofilm eradication concentration) values reaching 8 and 16 µg/mL, respectively. The cytotoxic effect of the novel nanoformula was also assessed against WI-38 fibroblasts vero (normal) cells (IC50 = 0.089 mg/mL) while nano-gold and nano-Lavandula angustifolia showed higher results (IC50 = 0.529, and 0.209 mg/mL, respectively). Nano-gold/nano-Lavandula angustifolia formula possessed a powerful wound healing efficacy with a 96.78% wound closure. These findings revealed that nano-gold/nano-Lavandula angustifolia nanoemulsion can inhibit bacterial growth and accelerate the wound healing rate.

Effect of Physiological Fluid on the Photothermal Properties of Gold Nanostructured

Colloidal gold particles have been extensively studied for their potential in hyperthermia treatment due to their ability to become excited in the presence of an external laser. However, their light-to-heat efficiency is affected by the physiologic environment. In this study, we aimed to evaluate the ability of gold sphere, rod, and star-shaped colloids to elevate the temperature of blood plasma and breast cancer-simulated fluid under laser stimulation. Additionally, the dependence of optical properties and colloid stability of gold nanostructures with physiological medium, particle shape, and coating was determined. The light-to-heat efficiency of the gold particle is shape-dependent. The light-to-heat conversion efficiency of a star-shaped colloid is 36% higher than that of sphere-shaped colloids. However, the raised temperature of the surrounding medium is the lowest in the star-shaped colloid. When gold nanostructures are exited with a laser stimulation in a physiological fluid, the ions/cations attach to the surface of the gold particles, resulting in colloidal instability, which limits electron oscillation and diminishes the energy generated by the plasmonic excitation. Fluorescein (Fl) and polyethylene glycol (PEG) attached to gold spheres enhances their colloidal stability and light-to-heat efficiency; post-treatment, they remand their optical properties.

Optimizing Dacarbazine Therapy: Design of a Laser-Triggered Delivery System Based on β-Cyclodextrin and Plasmonic Gold Nanoparticles

Dacarbazine (DB) is an antineoplastic drug extensively used in cancer therapy. However, present limitations on its performance are related to its low solubility, instability, and non-specificity. To overcome these drawbacks, DB was included in β-cyclodextrin (βCD), which increased its aqueous solubility and stability. This new βCD@DB complex has been associated with plasmonic gold nanoparticles (AuNPs), and polyethylene glycol (PEG) has been added in the process to increase the colloidal stability and biocompatibility. Different techniques revealed that DB allows for a dynamic inclusion into βCD, with an association constant of 80 M^-1 and a degree of solubilization of 0.023, where βCD showed a loading capacity of 16%. The partial exposure of the NH₂ group in the included DB allows its interaction with AuNPs, with a loading efficiency of 99%. The PEG-AuNPs-βCD@DB nanosystem exhibits an optical plasmonic absorption at 525 nm, a surface charge of -29 mV, and an average size of 12 nm. Finally, laser irradiation assays showed that DB can be released from this platform in a controlled manner over time, reaching a concentration of 56 μg/mL (43% of the initially loaded amount), which, added to the previous data, validates its potential for drug delivery applications. Therefore, the novel nanosystem based on βCD, AuNPs, and PEG is a promising candidate as a new nanocarrier for DB.

Anticancer therapeutic potential of phosphorylated galactosylated chitosan against N-nitrosodiethyl amine-induced hepatocarcinogenesis

Chitosan is a natural polyfunctional polymer that can be modified to achieve compounds with tailored properties for targeting and treating different cancers. In this study, we report the development and anticancer potential of phosphorylated galactosylated chitosan (PGC). The synthesized compound was characterized by FT-IR, NMR, and mass spectroscopy. The interaction of PGC with asialoglycoprotein receptors (ASGPR) and cellular internalization in HepG2 cells was studied using in silico and uptake studies respectively. PGC was evaluated for its metal chelating, ferric ion reducing, superoxide, and lipid peroxide (LPO) inhibiting potential. Further, anticancer therapeutic potential of PGC was evaluated against N-nitrosodiethylamine (NDEA)-induced hepatocellular carcinoma in a mice model. After development of cancer, PGC was administered to the treatment group (0.5 mg/kg bw, intravenously), once a week for 4 weeks. Characterization studies of PGC revealed successful phosphorylation and galactosylation of chitosan. A strong interaction of PGC with ASGP-receptors was predicted by computational studies and cellular internalization studies demonstrated 98.76 ± 0.53% uptake of PGC in the HepG2 cells. A good metal chelating, ferric ion reducing, and free radical scavenging activity was demonstrated by PGC. The anticancer therapeutic potential of PGC was evident from the observation that PGC treatment increased number of tumor free animals (50%) (6/12) and significantly (p ≤ 0.05) lowered tumor multiplicity as compared to untreated tumor group.

Effect of Nanoparticle Synthetic Conditions on Ligand Coating Integrity and Subsequent Nano-Biointeractions

Most current nanoparticle formulations have relatively low clearance efficiency, which may hamper their likelihood for clinical translation. Herein, we sought to compare the clearance and cellular distribution profiles between sub-5 nm, renally-excretable silver sulfide nanoparticles (Ag₂S-NPs) synthesized via either a bulk, high temperature, or a microfluidic, room temperature approach. We found that the thermolysis approach led to significant ligand degradation, but the surface coating shell was unaffected by the microfluidic synthesis. We demonstrated that the clearance was improved for Ag₂S-NPs with intact ligands, with less uptake in the liver. Moreover, differential distribution in hepatic cells was observed, where Ag₂S-NPs with degraded coatings tend to accumulate in Kupffer cells and those with intact coatings are more frequently found in hepatocytes. Therefore, understanding the impact of synthetic processes on ligand integrity and subsequent nano-biointeractions will aid in designing nanoparticle platforms with enhanced clearance and desired distribution profiles.

Emerging trends in the application of gold nanoformulations in colon cancer diagnosis and treatment

Colorectal cancer is one of the most aggressive types of cancer with about two million new cases and one million deaths in 2020. The side effects of the available chemotherapies and the possibility of developing resistance against treatment highlight the importance of developing new therapeutic options. The development in the field of nanotechnology have introduced the application of nanoparticles (NPs) as a promising approach in the diagnosis and treatments of colorectal cancer and other types of cancer. Gold nanoparticles (AuNPs) are currently one of the most studied materials as they possess unique tunable properties allowing them to play a role in colorectal cancer bioimaging, diagnosis, and therapy. The high surface-to-volume ratio of AuNPs mediates their utilization in drug delivery as well as functionalization to provide specific targeting. Moreover, depending on their physical properties (size, shape), AuNPs can be modified to fit the intended application. However, there are contradictory results around the pharmacokinetics of AuNPs including their biodistribution, clearance, and toxicity. This variation of opinions is most likely due to the development of different AuNPs that vary in shape, size, and surface chemistry, in addition to the conditions under which each research was carried out. The conflicting data represent a challenge in the clinical use of AuNPs suggesting the need to understand the toxicity, fate, and long-term exposure of AuNPs in vivo. Thus, there is an unmet need for the establishment of a publicly available data base for extensive analysis. In this review, we discuss the recent advances in AuNP applications in the treatment and diagnosis of colorectal cancer, mechanisms of action, and clinical challenges.

Nanostructured Surface Finishing and Coatings: Functional Properties and Applications

This review presents current literature on different nanocomposite coatings and surface finishing for textiles, and in particular this study has focused on smart materials, drug-delivery systems, industrial, antifouling and nano/ultrafiltration membrane coatings. Each of these nanostructured coatings shows interesting properties for different fields of application. In this review, particular attention is paid to the synthesis and the consequent physico-chemical characteristics of each coating and, therefore, to the different parameters that influence the substrate deposition process. Several techniques used in the characterization of these surface finishing coatings were also described. In this review the sol-gel method for preparing stimuli-responsive coatings as smart sensor materials is described; polymers and nanoparticles sensitive to pH, temperature, phase, light and biomolecules are also treated; nanomaterials based on phosphorus, borates, hydroxy carbonates and silicones are used and described as flame-retardant coatings; organic/inorganic hybrid sol-gel coatings for industrial applications are illustrated; carbon nanotubes, metallic oxides and polymers are employed for nano/ultrafiltration membranes and antifouling coatings. Research institutes and industries have collaborated in the advancement of nanotechnology by optimizing conversion processes of conventional materials into coatings with new functionalities for intelligent applications.

Gold nanoparticle-conjugated nanomedicine: design, construction, and structure-efficacy relationship studies

In comparison with conventional therapies, nanomedicine shows prominent clinical performance, with better therapeutic efficacy and less off-target toxicity. As an important component of nanomedicine, gold nanoparticle (GNP)-based nanodrugs have attracted considerable interest because of their excellent performance given by the unique structure. Although no pharmaceutical formulations of GNP-associated nanodrugs have been officially marketed yet, a substantial amount of research on this aspect is being carried out, producing numerous GNP-based drug delivery systems with potential clinical applications. In this review, we present an overview of our progress on GNP-based nanodrugs combined with other achievements in biomedical applications, including drug-conjugated GNPs prepared for disease treatments and specific tumour targeting, structure-efficacy relationship (SER) studies on GNP-conjugated nanodrugs, and therapeutic hybrid nanosystems composed of GNPs. In addition, we also put forward some proposals to guide future work in developing GNP-based nanomedicine. We hope that this review will offer some useful experience for our peers and GNP-based nanodrugs will be utilized in the clinic with further persistent efforts.

Dark Field and Coherent Anti-Stokes Raman (DF-CARS) Imaging of Cell Uptake of Core-Shell, Magnetic-Plasmonic Nanoparticles

Magnetic-plasmonic, Fe₃O₄-Au, core-shell nanoparticles are popular in many applications, most notably in therapeutics and diagnostics, and thus, the imaging of these nanostructures in biological samples is of high importance. These nanostructures are typically imaged in biological material by dark field scatter imaging, which requires an even distribution of nanostructures in the sample and, therefore, high nanoparticle doses, potentially leading to toxicology issues. Herein, we explore the nonlinear optical properties of magnetic nanoparticles coated with various thicknesses of gold using the open aperture z-scan technique to determine the nonlinear optical properties and moreover, predict the efficacy of the nanostructures in nonlinear imaging. We find that the magnetic nanoparticles coated with gold nanoseeds and thinner gold shells (ca. 4 nm) show the largest nonlinear absorption coefficient β and imaginary part of the third-order susceptibility Im χ⁽³⁾, suggesting that these nanostructures would be suitable contrast agents. Next, we combine laser dark field microscopy and epi-detected coherent anti-Stokes Raman (CARS) microscopy to image the uptake of magnetic-plasmonic nanoparticles in human pancreatic cancer cells. We show the epi-detected CARS technique is suitable for imaging of the magnetic-plasmonic nanoparticles without requiring a dense distribution of nanoparticles. This technique achieves superior nanoparticle contrasting over both epi-detected backscatter imaging and transmission dark field imaging, while also attaining label-free chemical contrasting of the cell. Lastly, we show the high biocompatibility of the Fe₃O₄ nanoparticles with ca. 4-nm thick Au shell at concentrations of 10-100 µg/mL.

Gold Nanoparticles Conjugated L-Lysine for Improving Cisplatin Delivery to Human Breast Cancer Cells

INTRODUCTION

Nano drug delivery is a broad field of research on the development of novel nano- carrier systems for effective therapeutic delivery of drugs. Here, an anticancer drug, cisplatin (CDDP) conjugated Gold Nanoparticles (GNPs) via L-Lysine (Lys) linker.

METHODS

The produced nanodrug (GNPs-Lys-CDDP) was characterized by UV-Vis spectroscopy, Dynamic Light Scattering (DLS), Zeta potentials and electron force microscopy. The cytotoxic efficacy of the GNPs-Lys-CDDP against human breast cancer cells (SKBR3) and normal cells (MCF- 10A) was evaluatedby MTT assay. Cell apoptosis and morphology changes were assessed by flowcytometery and Acridine Orange/Ethidium Bromide (AO/EtBr) staining, respectively.

RESULTS

It was found that the GNPs-Lys-CDDP with a size of 85 nm and negatively charged with a zeta-potential of about -25 mV could be taken up by tumor cells. A marked change in the UV spectrum of GNPs-Lys-CDDP compare to GNPs showed a strong absorption shift in the 525 nm region. The LD 50 of GNPs-Lys-CDDP against SKBR3 (1 μg.mL -1), was found to be 8 times lower than that of naked CDDP against SKBR3 (8 μg.mL -1). The nanocomplex GNPs-Lys-CDDP also significantly increased the apoptosis of SKBR3 with the lowest cytotoxic effects on normal cells.

DISCUSSION

This work indicates that GNPs effectively could decrease the lethal dose of CDDP to 87%. Hence, GNPs modified by Lys, could be a good nano-carrier for chemotherapeutic drugs.

Roadmap for metal nanoparticles in radiation therapy: current status, translational challenges, and future directions

This roadmap outlines the potential roles of metallic nanoparticles (MNPs) in the field of radiation therapy. MNPs made up of a wide range of materials (from Titanium, Z = 22, to Bismuth, Z = 83) and a similarly wide spectrum of potential clinical applications, including diagnostic, therapeutic (radiation dose enhancers, hyperthermia inducers, drug delivery vehicles, vaccine adjuvants, photosensitizers, enhancers of immunotherapy) and theranostic (combining both diagnostic and therapeutic), are being fabricated and evaluated. This roadmap covers contributions from experts in these topics summarizing their view of the current status and challenges, as well as expected advancements in technology to address these challenges.

Intranasal administration of gold nanoparticles designed to target the central nervous system: Fabrication and comparison between nanospheres and nanoprisms

The presence of the blood-brain barrier (BBB) limit gold nanoparticles (GNP) accumulation in central nervous system (CNS) after intravenous (IV) administration. The intranasal (IN) route has been suggested as a good strategy for circumventing the BBB. In this report, we used gold nanoprisms (78 nm) and nanospheres (47 nm), of comparable surface areas (8000 vs 7235 nm²) functionalized with a polyethylene glycol (PEG) and D1 peptide (GNPr-D1 and GNS-D1, respectively) to evaluate their delivery to the CNS after IN administration. Cell viability assay showed that GNPr-D1 and GNS-D1 were not cytotoxic at concentrations ranged between 0.05 and 0.5 nM. IN administration of GNPr-D1 and GNS-D1 demonstrated a significant difference between the two types of GNP, in which the latter reached the CNS in higher levels. Pharmacokinetic study showed that the peak brain level of gold was 0.75 h after IN administration of GNS-D1. After IN and IV administrations of GNS-D1, gold concentrations found in brain were 55 times higher via the IN route compared to IV administration. Data revealed that the IN route is more effective for targeting gold to the brain than IV administration. Finally, no significant difference was observed between the IN and IV routes in the distribution of GNS-D1 in the various brain areas.

Delivery of drugs, proteins, and nucleic acids using inorganic nanoparticles

Inorganic nanoparticles provide multipurpose platforms for a broad range of delivery applications. Intrinsic nanoscopic properties provide access to unique magnetic and optical properties. Equally importantly, the structural and functional diversity of gold, silica, iron oxide, and lanthanide-based nanocarriers provide unrivalled control of nanostructural properties for effective transport of therapeutic cargos, overcoming biobarriers on the cellular and organismal level. Taken together, inorganic nanoparticles provide a key addition to the arsenal of delivery vectors for fighting disease and improving human health.

Thiolated polymers: Bioinspired polymers utilizing one of the most important bridging structures in nature

Thiolated polymers designated "thiomers" are obtained by covalent attachment of thiol functionalities on the polymeric backbone of polymers. In 1998 these polymers were first described as mucoadhesive and in situ gelling compounds forming disulfide bonds with cysteine-rich substructures of mucus glycoproteins and crosslinking through inter- and intrachain disulfide bond formation. In the following, it was shown that thiomers are able to form disulfides with keratins and membrane-associated proteins exhibiting also cysteine-rich substructures. Furthermore, permeation enhancing, enzyme inhibiting and efflux pump inhibiting properties were demonstrated. Because of these capabilities thiomers are promising tools for drug delivery guaranteeing a strongly prolonged residence time as well as sustained release on mucosal membranes. Apart from that, thiomers are used as drugs per se. In particular, for treatment of dry eye syndrome various thiolated polymers are in development and a first product has already reached the market. Within this review an overview about the thiomer-technology and its potential for different applications is provided discussing especially the outcome of studies in non-rodent animal models and that of numerous clinical trials. Moreover, an overview on product developments is given.

Stabilizing gold nanoparticles for use in X-ray computed tomography imaging of soil systems

This investigation establishes a system of gold nanoparticles that show good colloidal stability as an X-ray computed tomography (XCT) contrast agent under soil conditions. Gold nanoparticles offer numerous beneficial traits for experiments in biology including: comparatively minimal phytotoxicity, X-ray attenuation of the material and the capacity for functionalization. However, soil salinity, acidity and surface charges can induce aggregation and destabilize gold nanoparticles, hence in biomedical applications polymer coatings are commonly applied to gold nanoparticles to enhance stability in the in vivo environment. Here we first demonstrate non-coated nanoparticles aggregate in soil-water solutions. We then show coating with a polyethylene glycol (PEG) layer prevents this aggregation. To demonstrate this, PEG-coated nanoparticles were drawn through flow columns containing soil and were shown to be stable; this is in contrast with control experiments using silica and alumina-packed columns. We further determined that a suspension of coated gold nanoparticles which fully saturated soil maintained stability over at least 5 days. Finally, we used time resolved XCT imaging and image based models to approximate nanoparticle diffusion as similar to that of other typical plant nutrients diffusing in water. Together, these results establish the PEGylated gold nanoparticles as potential contrast agents for XCT imaging in soil.

Transfollicular delivery of gold microparticles in healthy skin and acne vulgaris, assessed by in vivo reflectance confocal microscopy and optical coherence tomography

INTRODUCTION

Topical application of gold microparticles (GMPs) for selective photothermolysis is a recently FDA-cleared therapy for acne vulgaris. Current evidence indicates the potential of optical imaging to non-invasively visualize GMPs and describe photothermal tissue effects.

OBJECTIVES

To qualitatively and quantitatively describe GMP delivery in vivo and visualize laser-mediated thermal effects of GMPs in facial skin of acne patients and healthy participants, using reflectance confocal microscopy (RCM) and optical coherence tomography (OCT).

METHODS

Patients with facial acne (n = 14), and healthy participants (n = 7) were included. RCM and OCT images were acquired at baseline, after GMP application, and after diode laser exposure. All images were evaluated qualitatively and quantitatively with regards to GMP delivery in skin layers and morphological thermal effects. Lastly, skin biopsies were obtained to compare RCM and OCT findings to histology.

RESULTS

GMPs were delivered equally in healthy participants and acne patients, and in lesional and non-lesional acne skin. In RCM images, GMPs appeared as hyperreflective aggregates inside hair follicles and eccrine ducts, corresponding to natural skin openings (NSOs). The fraction of NSOs with hyperreflective content increased significantly after GMP application compared to baseline (50-75% increase, P = 8.88 × 10-16 ). Similarly, in OCT images, GMPs appeared as hyperreflective columns inside hair follicles and were not detected in surrounding skin. GMPs reached a maximum depth of 920 μm (median 300 μm). After laser exposure, RCM and histology revealed selective perifollicular tissue changes around NSOs.

CONCLUSION

Optical imaging visualizes GMP delivery and thermal tissue response following laser exposure and enables bedside monitoring of transfollicular microparticle delivery. Lasers Surg. Med. 51:430-438, 2019. © 2019 Wiley Periodicals, Inc.

Hyaluronic Acid-Coated Nanomedicine for Targeted Cancer Therapy

Hyaluronic acid (HA) has been widely investigated in cancer therapy due to its excellent characteristics. HA, which is a linear anionic polymer, has biocompatibility, biodegradability, non-immunogenicity, non-inflammatory, and non-toxicity properties. Various HA nanomedicines (i.e., micelles, nanogels, and nanoparticles) can be prepared easily using assembly and modification of its functional groups such as carboxy, hydroxy and N-acetyl groups. Nanometer-sized HA nanomedicines can selectively deliver drugs or other molecules into tumor sites via their enhanced permeability and retention (EPR) effect. In addition, HA can interact with overexpressed receptors in cancer cells such as cluster determinant 44 (CD44) and receptor for HA-mediated motility (RHAMM) and be degraded by a family of enzymes called hyaluronidase (HAdase) to release drugs or molecules. By interaction with receptors or degradation by enzymes inside cancer cells, HA nanomedicines allow enhanced targeting cancer therapy. In this article, recent studies about HA nanomedicines in drug delivery systems, photothermal therapy, photodynamic therapy, diagnostics (because of the high biocompatibility), colloidal stability, and cancer targeting are reviewed for strategies using micelles, nanogels, and inorganic nanoparticles.

Potential of contrast agents to enhance in vivo confocal microscopy and optical coherence tomography in dermatology: A review

Distinction between normal skin and pathology can be a diagnostic challenge. This systematic review summarizes how various contrast agents, either topically delivered or injected into the skin, affect distinction between skin disease and normal skin when imaged by optical coherence tomography (OCT) and confocal microscopy (CM). A systematic review of in vivo OCT and CM studies using exogenous contrast agents on healthy human skin or skin disease was performed. In total, nine CM studies and one OCT study were eligible. Four contrast agents aluminum chloride (AlCl) n = 2, indocyanine green (ICG) n = 3, sodium fluorescein n = 3 and acetic acid n = 1 applied to CM in variety of skin diseases. ICG, acetic acid and AlCl showed promise to increase contrast of tumor nests in keratinocyte carcinomas. Fluorescein and ICG enhanced contrast of keratinocytes and adnexal structures. In OCT of healthy skin gold nanoshells, increased contrast of natural skin openings. Contrast agents may improve delineation and diagnosis of skin cancers; ICG, acetic acid and AlCl have potential in CM and gold nanoshells facilitate visualization of adnexal skin structures in OCT. However, as utility of bedside optical imaging increases, further studies with robust methodological quality are necessary to implement contrast agents into routine dermatological practice.

Rapid synthesis of gold nanoparticles with carbon monoxide in a microfluidic segmented flow system

A microfluidic reactor offers a controllable and convenient platform for fast synthesis of gold nanoparticles with carbon monoxide.

Effect of Surface Coating of Gold Nanoparticles on Cytotoxicity and Cell Cycle Progression

Gold nanoparticles (GNPs) are usually wrapped with biocompatible polymers in biomedical field, however, the effect of biocompatible polymers of gold nanoparticles on cellular responses are still not fully understood. In this study, GNPs with/without polymer wrapping were used as model probes for the investigation of cytotoxicity and cell cycle progression. Our results show that the bovine serum albumin (BSA) coated GNPs (BSA-GNPs) had been transported into lysosomes after endocytosis. The lysosomal accumulation had then led to increased binding between kinesin 5 and microtubules, enhanced microtubule stabilization, and eventually induced G₂/M arrest through the regulation of cadherin 1. In contrast, the bare GNPs experienced lysosomal escape, resulting in microtubule damage and G₀/G₁ arrest through the regulation of proliferating cell nuclear antigen. Overall, our findings showed that both naked and BSA wrapped gold nanoparticles had cytotoxicity, however, they affected cell proliferation via different pathways. This will greatly help us to regulate cell responses for different biomedical applications.

Applications of Noble Metal-Based Nanoparticles in Medicine

Nanoparticles have unique, size-dependent properties, which means they are widely used in various branches of industry. The ability to control the properties of nanoparticles makes these nanomaterials very interesting for medicine and pharmacology. The application of nanoparticles in medicine is associated with the design of specific nanostructures, which can be used as novel diagnostic and therapeutic modalities. There are a lot of applications of nanoparticles, e.g., as drug delivery systems, radiosensitizers in radiation or proton therapy, in bioimaging, or as bactericides/fungicides. This paper aims to introduce the characteristics of noble metal-based nanoparticles with particular emphasis on their applications in medicine and related sciences.

Histone-Mimetic Gold Nanoparticles as Versatile Scaffolds for Gene Transfer and Chromatin Analysis

Histone-inspired polymer assemblies (polyplexes) can regulate gene expression and subcellular transport in plasmids by harnessing the cellular machinery normally used for histone proteins. When grafted to polyplexes, histone tails promote nuclear accumulation, trigger plasmid DNA (pDNA) release, and enhance transcription. Herein, we developed multifunctional gold nanoparticles (AuNPs) decorated by histone motifs as histone-inspired scaffolds with improved pDNA binding, easy bioimaging, and increased potential for gene delivery and chromatin analysis applications. We hypothesized that polycationic AuNPs coupled to histone motifs would mimic the native presentation of these sequences on the histone octamer and thereby create structures with the capacity to both engage native histone effectors and condense pDNA into nucleosome-inspired nanostructures. AuNPs bearing ∼2 nm cores were prepared based on the well-established Brust-Schiffrin two-phase method involving tetrachloroaurate reduction in the presence of 1-pentanethiol. Solid phase peptide synthesis was employed to generate thiolated polycationic ligands and histone tail motifs, and the AuNPs and peptide ligands were combined in a two-step Murray place exchange reaction at various ratios to produce a collection of polycationic AuNPs modified with varying amounts of histone tails. Electron microscopy and thermal analyses demonstrated that these modified AuNPs exhibited tunable biochemical and biophysical properties that closely mimicked the properties of native histones. The histone-mimetic nanoscaffolds efficiently and sequence-specifically engaged histone effectors responsible for activating transcription. In addition, the nanoscaffolds condensed pDNA into complexes with high stability in the presence of physiological concentrations of heparin, a common extracellular polyanion. These combined properties of histone engagement and high stability led to a ∼6-fold enhancement in transfection efficiency as compared with typical polymeric transfection reagents, with the increased transfection efficiency correlated to the presence and amount of histone tails displayed on the surface of the nanoscaffolds. These findings demonstrate the utility of employing a biomimetic materials design approach to develop more effective and stable delivery vehicles for gene transfer and chromatin analysis applications.

Synthesis of highly stable and biocompatible gold nanoparticles for use as a new X-ray contrast agent

This work reports a novel reduction procedure for the synthesis of Gum Arabic (GA) capped-gold nanoparticles (AuNPs) in glucosammonium formate as a new ionic liquid. The GA coated AuNPs show good stability in physiological media. The synthesized AuNPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, dynamic light scattering and X-ray diffraction analysis. These stable AuNPs are introduced as a new contrast agent for X-ray Computed Tomography (X-ray CT). These nanoparticles have higher contrasting properties than the commercial contrast agent, Visipaque. The precursors used (Gum Arabic and glucose based-ionic liquid) for synthesis of AuNPs are biocompatible and non-toxic.

Gold nanospheres enhanced photothermal therapy in a rat model

BACKGROUND AND OBJECTIVE

Efficient photothermal conversion of gold nanoparticles with strong light absorption suggests their wide use as selective photothermal agents in biomedical fields. The aim of this study is to investigate the use of gold nanospheres (GNPs) as exogenous visible light absorbers to improve laser treatment of port-wine stains.

MATERIALS AND METHODS

Thiol-terminated methoxypolyethylene glycol modified GNPs (PEG-GNPs) with peak extinction matching the visible light wavelength of the laser being used were synthesized. An in vitro capillary experiment was prepared to investigate the thermal response of blood vessels with and without injection of 4.54 mg PEG-GNPs in mice prior to irradiation by a frequency-doubled Nd:YAG laser at a wavelength of 532 nm.

RESULTS

The in vitro results demonstrated that the photocoagulation size in blood vessels after exposed to laser light increased with the increment of concentration of PEG-GNPs in blood within a certain range. However, the unwanted thermal response (i.e., cavitation) occurred when the concentration of PEG-GNPs in blood was larger than 2.5 mg/ml. The in vivo results suggested that more obvious blood thermal response can be induced by laser light after injection of PEG-GNPs. After injection of 4.54 mg PEG-GNPs, laser radiant exposure required for thread-like constriction of blood vessels decreased from 12.5 to 9.8 J/cm2 with the pulse duration of 10 ms, from 15 to 11.85 J/cm2 with the pulse duration of 30 ms, respectively.

CONCLUSION

This in vitro and in vivo experimental results show that PEG-GNPs combined with laser light could be a promising modality to reduce the radiant exposure required for obvious blood thermal response, thereby providing a potential strategy for improving the laser treatment of cutaneous vascular lesions. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

Junction opener protein increases nanoparticle accumulation in solid tumors

Carcinomas contain tight junctions that can limit the penetration and therefore therapeutic efficacy of anticancer agents, especially those delivered by nano-carrier systems. The junction opener (JO) protein is a virus-derived protein that can transiently open intercellular junctions in epithelial tumors by cleaving the junction protein desmoglein-2 (DSG2). Co-administration of JO was previously shown to significantly increase the efficacy of various monoclonal antibodies and chemotherapy drugs in murine tumor models by allowing for increased intratumoral penetration of the drugs. To investigate the size-dependent effect of JO on nanocarriers, we used PEGylated gold nanoparticles (AuNPs) of two different sizes as model drugs and investigated their biodistribution following JO protein treatment. By inductively coupled plasma mass spectrometry (ICP-MS), JO was found to significantly increase bulk tumor accumulation of AuNPs of 35nm but not 120nm particles in both medium (200-300mm³) and large (500-600mm³) tumors. Image analysis of tumor sections corroborates this JO-mediated increase in tumor accumulation of AuNPs. Quantitative intratumoral distribution analyses show that most nanoparticles were found within 100μm of the vasculature, and that the penetration profiles of AuNPs are not significantly affected by JO treatment at the 6h timepoint.

Length vs. stiffness: which plays a dominant role in the cellular uptake of fructose-based rod-like micelles by breast cancer cells in 2D and 3D cell culture models?

Internalization of rod-like micelles by breast cancer cells is significantly affected by the stiffness of nano-rods.

Gold nanoparticle-based colorimetric biosensors

Gold nanoparticles (AuNPs) provide excellent platforms for the development of colorimetric biosensors as they can be easily functionalised, displaying different colours depending on their size, shape and state of aggregation. In the last decade, a variety of biosensors have been developed to exploit the extent of colour changes as nano-particles (NPs) either aggregate or disperse, in the presence of analytes. Of critical importance to the design of these methods is that the behaviour of the systems has to be reproducible and predictable. Much has been accomplished in understanding the interactions between a variety of substrates and AuNPs, and how these interactions can be harnessed as colorimetric reporters in biosensors. However, despite these developments, only a few biosensors have been used in practice for the detection of analytes in biological samples. The transition from proof of concept to market biosensors requires extensive long-term reliability and shelf life testing, and modification of protocols and design features to make them safe and easy to use by the population at large. Developments in the next decade will see the adoption of user friendly biosensors for point-of-care and medical diagnosis as innovations are brought to improve the analytical performances and usability of the current designs. This review discusses the mechanisms, strategies, recent advances and perspectives for the use of AuNPs as colorimetric biosensors.

Influence of PEG coating on the oral bioavailability of gold nanoparticles in rats

Metallic nanoparticles can be produced in a variety of shapes, sizes, and surface chemistries, making them promising potential tools for drug delivery. Most studies to date have evaluated uptake of metallic nanoparticles from the GI tract with methods that are at best semi-quantitative. This study used the classical method of comparing blood concentration area under the curve (AUC) following intravenous and oral doses to determine the oral bioavailability of 1, 2 and 5 kDa PEG-coated 5 nm gold nanoparticles (AuNPs). Male rats were given a single intravenous dose (0.8 mg/kg) or oral (gavage) dose (8 mg/kg) of a PEG-coated AuNP, and the concentration of gold was measured in blood over time and in tissues (liver, spleen and kidney) at sacrifice. Blood concentrations following oral administration were inversely related to PEG size, and the AUC in blood was significantly greater for the 1 kDa PEG-coated AuNPs than particles coated with 2 or 5 kDa PEG. However, bioavailabilities of all of the particles were very low (< 0.1%). Concentrations in liver, spleen and kidney were similar after the intravenous doses, but kidney showed the highest concentrations after an oral dose. In addition to providing information on the bioavailability of AuNPs coated with PEG in the 1-5 kDa range, this study demonstrates the utility of applying the blood AUC approach to assess the quantitative oral bioavailability of metallic nanoparticles.

Intraorgan Targeting of Gold Conjugates for Precise Liver Cancer Treatment

Intraorgan targeting of chemical drugs at tumor tissues is essential in the treatment of solid tumors that express the same target receptor as normal tissues. Here, asialoglycoprotein receptor (ASGP-R)-targeting paclitaxel-conjugated gold nanoparticles (Gal/PTX-GNPs) are fabricated as a demonstration to realize the precise treatment of liver cancer. The enhanced biological specificity and therapeutic performance of drugs loaded on nanoparticles not only rely on the ligands on carriers for receptor recognition but are also determined by the performance of gold conjugates with designed structure. The tumor cell selectivity of the designed conjugates in liver tumor (HepG2) cells is close to six times of that incubated with control conjugates without galactose modification in liver normal (L02) cells. The drug level in tumor versus liver of Gal/PTX-GNPs is 121.0% at 8 h post injection, a 15.7-fold increase in the tumor specificity compared to that of GNPs conjugated with PTX only. This intraorgan-targeting strategy results in a considerable improvement of performance in treating both Heps heterotopic and orthotopic xenograft tumor models, which is expected to be used for the enhanced antitumor efficacy and reduced hepatotoxicity in liver cancer treatment.

Molecular Tools for Facilitative Carbohydrate Transporters (Gluts)

Facilitative carbohydrate transporters-Gluts-have received wide attention over decades due to their essential role in nutrient uptake and links with various metabolic disorders, including diabetes, obesity, and cancer. Endeavors directed towards understanding the mechanisms of Glut-mediated nutrient uptake have resulted in a multidisciplinary research field spanning protein chemistry, chemical biology, organic synthesis, crystallography, and biomolecular modeling. Gluts became attractive targets for cancer research and medicinal chemistry, leading to the development of new approaches to cancer diagnostics and providing avenues for cancer-targeting therapeutics. In this review, the current state of knowledge of the molecular interactions behind Glut-mediated sugar uptake, Glut-targeting probes, therapeutics, and inhibitors are discussed.

Cell membrane-derived nanomaterials for biomedical applications

The continued evolution of biomedical nanotechnology has enabled clinicians to better detect, prevent, manage, and treat human disease. In order to further push the limits of nanoparticle performance and functionality, there has recently been a paradigm shift towards biomimetic design strategies. By taking inspiration from nature, the goal is to create next-generation nanoparticle platforms that can more effectively navigate and interact with the incredibly complex biological systems that exist within the body. Of great interest are cellular membranes, which play essential roles in biointerfacing, self-identification, signal transduction, and compartmentalization. In this review, we explore the major ways in which researchers have directly leveraged cell membrane-derived biomaterials for the fabrication of novel nanotherapeutics and nanodiagnostics. Such emerging technologies have the potential to significantly advance the field of nanomedicine, helping to improve upon traditional modalities while also enabling novel applications.

A facile synthesis of size- and shape-controlled Gd(OH)3 nanoparticles and Gd(OH)3@Au core/shell nanostars

A facile hydrothermal route was developed to generate size- and shape-controlled (Gd(OH)₃) nanoparticles and polyethylenimine-stabilized Gd(OH)₃@Au core/shell nanostars with photothermal properties.

Fluorescent Indicator Displacement Assay: Ultrasensitive Detection of Glutathione and Selective Cancer Cell Imaging

This Research Article reports the development of nanohybrid comprising of anionic carbon dots (ACD) protected gold nanoparticle (GNP). ACD directly cap GNP through its anionic surface functionalization leading to the formation of stable aqueous GNP dispersion. This newly developed ACD-GNP nanohybrid has been thoroughly characterized by different spectroscopic and microscopic techniques. This nanohybrid is successfully employed toward the selective sensing of glutathione (GSH). The mechanism of GSH sensing by this nanosensor is based on the GSH triggered displacement of fluorescent indicator ACD from the GNP surface. Upon capping GNP, intrinsic fluorescence of ACD gets quenched. Addition of GSH displaces the fluorescent indicator ACD from GNP surface and restores the fluorescence signal of ACD. This nanosensor exhibits very high selectivity as well as sensitivity toward glutathione over the other biothiols and can detect as low as 6 nM of GSH. More importantly, selective imaging of the cancer cells over the noncancerous cells was achieved by this ACD-GNP hybrid implying its potential applications in biosensing, as well as in cancer diagnosis.

Xanthan gum stabilized PEGylated gold nanoparticles for improved delivery of curcumin in cancer

In recent years, gold nanoparticles (AuNPs) have received immense interest in various biomedical applications including drug delivery, photothermal ablation of cancer and imaging agent for cancer diagnosis. However, the synthesis of AuNPs poses challenges due to the poor reproducibility and stability of the colloidal system. In the present work, we developed a one step, facile procedure for the synthesis of AuNPs from hydrogen tetrachloroaurate (III) hydrate (HAuCl4. 3H2O) by using ascorbic acid and xanthan gum (XG) as reducing agent and stabilizer, respectively. The effect of concentrations of HAuCl4, 3H2O, ascorbic acid and methoxy polyethylene glycol-thiol (mPEG800-SH) were optimized and it was observed that stable AuNPs were formed at concentrations of 0.25 mM, 50 μM and 1 mM for HAuCl4.3H2O, ascorbic acid, and mPEG800-SH, respectively. The XG stabilized, deep red wine colored AuNPs (XG-AuNPs) were obtained by drop-wise addition of aqueous solution of ascorbic acid (50 mM) and XG (1.5 mg ml(-1)). Synthesized XG-AuNPs showed λmax at 540 nm and a mean hydrodynamic diameter of 80 ± 3 nm. PEGylation was performed with mPEG800-SH to obtain PEGylated XG-AuNPs (PX-AuNPs) and confirmed by Ellman's assay. No significant shift observed in λmax and hydrodynamic diameter between XG-AuNPs and PX-AuNPs. Colloidal stability of PX-AuNPs was studied in normal saline, buffers within a pH range of 1.2-7.4, DMEM complete medium and in normal storage condition at 4 ˚C. Further, water soluble curcumin was prepared using PVP-K30 as solid dispersion and loaded on to PX-AuNPs (CPX-AuNPs), and evaluated for cellular uptake and cytotoxicity in Murine melanoma (B16F10) cells. Time and concentration dependent studies using CPX-AuNPs showed efficient uptake and decreased cell viability compared to free curcumin.

Cellular distribution of injected PLGA-nanoparticles in the liver

The cellular fate of nanoparticles in the liver is not fully understood. Because the effectiveness and safety of nanoparticles in liver therapy depends on targeting nanoparticles to the right cell populations, this study aimed to determine a relative distribution of PLGA-nanoparticles (sizes 271±1.4 nm) among liver cells in vivo. We found that Kupffer cells were the major cells that took up nanoparticles, followed by liver sinusoidal endothelial cells and hepatic stellate cells. Nanoparticles were found in only 7% of hepatocytes. Depletion of Kupffer cells by clodronate liposomes increased nanoparticle retention in liver sinusoidal endothelial cells and hepatic stellate cells, but not in hepatocytes. It is importantly suggested that studies of drug-loaded nanoparticle delivery to the liver have to demonstrate not only uptake of nanoparticles by the target cell type but also non-uptake by other cell types to assess their effect as well as ensure their safety.

Non-Invasive Imaging Serum Amyloid A Activation through the NF-κB Signal Pathway upon Gold Nanostructure Exposure

With the objective of investigating the acute activation of inflammatory cascades upon exposure to gold nanoparticles (GNPs) as well as detailing the mechanisms, a reporter mouse model that allows for non-invasive and longitudinal imaging of hepatic acute-phase serum amyloid A (SAA) activation is constructed. The model is able to visualize SAA activation at the transcriptional stage, with higher sensitivity than serum protein detection by ELISA. GNPs of various sizes (10-80 nm) and geometries are assessed using the reporter mice with results demonstrating that 50 nm nanospheres (GNS50) possess the highest capacity to induce hepatic SAA activation. Detailed analysis uncovers that resident macrophages in the liver are the main origins of these cytokines and that the exposure to GNS50 significantly induces the M1 macrophage phenotype. Moreover, those M1-polarized macrophages, together with the subsequently secreted pro-inflammatory cytokines, exert effects on hepatocytes and then initiate SAA transcription through the NF-κB signal pathway. The results detail the sequential reactions to GNPs among macrophages, inflammatory mediators, and SAA-synthesizing hepatocytes, which shed light on the acute effects of GNPs on the body. In addition, the established in situ and highly sensitive SAA detection system is expected to have vast applications in evaluating NP-induced acute inflammatory reactions.

Glyconanomaterials for biosensing applications

Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

Size-optimized galactose-capped gold nanoparticles for the colorimetric detection of heat-labile enterotoxin at nanomolar concentrations

The development of a galactose-capped gold nanoparticle-based colorimetric sensor for the detection of the lectin heat-labile enterotoxin is reported. Heat-labile enterotoxin is one of the pathogenic agents responsible for the intestinal disease called 'traveller's diarrhoea'. By means of specific interaction between galactose moieties attached to the surface of gold nanoparticles and receptors on the B-subunit of heat-labile enterotoxin (LTB), the gold nanoparticles reported here act as an efficient colorimetric sensor, which can detect the toxin at nanomolar concentrations. The effect of gold nanoparticle size on the detection sensitivity was investigated in detail. Amongst the various sizes of gold nanoparticles studied (2, 7, 12, and 20 nm), the 12 nm sized gold nanoparticles were found to be the most efficient, with a minimum heat-labile enterotoxin detection concentration of 100 nM. The red to purple colour change of the gold nanoparticle solution occurred within two minutes, indicating rapid toxin sensing.

Nanoparticle-liver interactions: Cellular uptake and hepatobiliary elimination

30-99% of administered nanoparticles will accumulate and sequester in the liver after administration into the body. This results in reduced delivery to the targeted diseased tissue and potentially leads to increased toxicity at the hepatic cellular level. This review article focuses on the inter- and intra-cellular interaction between nanoparticles and hepatic cells, the elimination mechanism of nanoparticles through the hepatobiliary system, and current strategies to manipulate liver sequestration. The ability to solve the "nanoparticle-liver" interaction is critical to the clinical translation of nanotechnology for diagnosing and treating cancer, diabetes, cardiovascular disorders, and other diseases.

Utilising inorganic nanocarriers for gene delivery

The delivery of genetic materials into cells to elicit cellular response has been extensively studied by biomaterials scientists globally.