Gold nanoparticles functionalized with therapeutic and targeted peptides for cancer treatment

Chemistry for oncotheranostic gold nanoparticles

This review presents in a comprehensive ways the chemical methods used to functionalize gold nanoparticles with focus on anti-cancer applications. The review covers the parameters required for the synthesis gold nanoparticles with defined shapes and sizes, method for targeted delivery in tumours, and selected examples of anti-cancers compounds delivered with gold nanoparticles. A short survey of bioassays for oncology based on gold nanoparticles is also presented.

Simultaneously targeted imaging cytoplasm and nucleus in living cell by biomolecules capped ultra-small GdOF nanocrystals

Simultaneously targeted imaging cytoplasm and nucleus in living cell by just one photoluminescent nanocrystals has been a giant challenge in nanobiotechnology and nanomedicine. Herein we report a novel Arg-Gly-Asp peptide (RGD) or cysteine (Cys) functionalized ultra-small GdOF nanocrystals for simultaneously targeted imaging cell cytoplasm and nucleus. As-prepared RGD@GdOF and Cys@GdOF nanocrystals possessed high water dispersibility, ultra-small size (about 5 nm) and double emissions (545 nm and 587 nm) with high quantum yield. Such functionalized nanocrystals presented high cellular biocompatibility and were successfully used to label living cells with very high signal to noise ratio. The living cells cytoplasm and nucleus (cancer cells and stem cells) could be imaged simultaneously through the mergence of green and red emission of nanocrystals, based on mechanism of fluorescent intensity difference. These functionalized nanocrystals also exhibited significantly higher photostability and brightness as compared to dyes. Such the ultra-small size, high photostability and intensity, double emissions, excellent biocompatibility and targeted ability, make as-prepared functionalized nanocrystals particularly promising for cellular and molecular-level bioimaging applications.

Single particle electrochemistry of p-hydroxythiophenol-labeled gold nanoparticles

Electroactive p-hydroxythiophenol (p-HTP) monolayer on a gold nanoparticle surface produced an amplified single particle-collision electrochemical signal.

Recent advances in gold nanoparticle-based bioengineering applications

The recently developed gold nanoparticle-based bioengineering technologies for biosensors,in vitroandin vivobioimaging, drug delivery systems for improved therapeutics and tissue engineering are discussed.

Structure and properties of citrate overlayers adsorbed at the aqueous Au(111) interface

One of the most common means of gold nanoparticle (AuNP) biofunctionalization involves the manipulation of precursor citrate-capped AuNPs via ligand displacement. However, the molecular-level structural characteristics of the citrate overlayer adsorbed at the aqueous Au interface at neutral pH remain largely unknown. Access to atomistic-scale details of these interfaces will contribute much needed insight into how AuNPs can be manipulated and exploited in aqueous solution. Here, the structures of such citrate overlayers adsorbed at the aqueous Au(111) interface at pH 7 are predicted and characterized using atomistic molecular dynamics simulations, for a range of citrate surface densities. We find that the overlayers are disordered in the surface density range considered, and that many of their key characteristics are invariant with surface density. In particular, we predict the overlayers to have 3-D, rather than 2-D, morphologies, with the anions closest to the gold surface being oriented with their carboxylate groups pointing away from the surface. We predict both striped and island morphologies for our overlayers, depending on the citrate surface density, and in all cases we find bare patches of the gold surface are present. Our simulations suggest that both citrate-gold adsorption and citrate-counterion pairing contribute to the stability of these citrate overlayer morphologies. We also calculate the free energy of adsorption at the aqueous Au(111) interface of a single citrate molecule, and compare this with the corresponding value for a single arginine molecule. These findings enable us to predict the conditions under which ligand displacement of surface-adsorbed citrate by arginine may take place. Our findings represent the first steps toward elucidating a more elaborate, detailed atomistic-scale model relating to the biofunctionalization of citrate-capped AuNPs.

Partial mitigation of gold nanoparticle interactions with human lymphocytes by surface functionalization with a ‘mixed matrix’

Aim: To investigate interactions of gold nanoparticles with primary human lymphocytes and determine if the addition of a self-assembled monolayer of ‘mixed-matrix’ ligands influenced these interactions. Materials & methods: The effect of gold nanoparticles was measured by exposure to peripheral blood mononuclear cells (PBMCs) from healthy volunteers with subsequent examination of cell proliferation, cytokine secretion and CD4+ T-cell activation relative to controls. Results: Capped and as-synthesized gold nanoparticles augmented PBMC proliferation in response to phytohemagglutinin and this effect was greater for as-synthesized than for capped gold nanoparticles. Release of IL-10 and IFN-γ from PBMCs was increased and the effect was again more marked for as-synthesized than capped gold nanoparticles. Conclusion: This method provides an ex vivo approach for studying the interaction of nanoparticles with the human immune system. Further research is required to determine the specific mechanisms for reduction of immune activation seen here which could then be used to design a truly ‘stealth’ nanoparticle.

Original submitted 11 October 2013; Revised submitted 30 January 2014

The emerging role of class-3 semaphorins and their neuropilin receptors in oncology

The semaphorins, discovered over 20 years ago, are a large family of secreted or transmembrane and glycophosphatidylinositol -anchored proteins initially identified as axon guidance molecules crucial for the development of the nervous system. It has now been established that they also play important roles in organ development and function, especially involving the immune, respiratory, and cardiovascular systems, and in pathological disorders, including cancer. During tumor progression, semaphorins can have both pro- and anti-tumor functions, and this has created complexities in our understanding of these systems. Semaphorins may affect tumor growth and metastases by directly targeting tumor cells, as well as indirectly by interacting with and influencing cells from the micro-environment and vasculature. Mechanistically, semaphorins, through binding to their receptors, neuropilins and plexins, affect pathways involved in cell adhesion, migration, invasion, proliferation, and survival. Importantly, neuropilins also act as co-receptors for several growth factors and enhance their signaling activities, while class 3 semaphorins may interfere with this. In this review, we focus on the secreted class 3 semaphorins and their neuropilin co-receptors in cancer, including aspects of their signaling that may be clinically relevant.

Biosafe nanoscale pharmaceutical adjuvant materials

Thanks to developments in the field of nanotechnology over the past decades, more and more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research. Nanomaterials possess unique properties which could be employed to develop drug carriers with longer circulation time, higher loading capacity, better stability in physiological conditions, controlled drug release, and targeted drug delivery. In this review article, we will review recent progress in the application of representative organic, inorganic and hybrid biosafe nanoscale materials in pharmaceutical research, especially focusing on nanomaterial-based novel drug delivery systems. In addition, we briefly discuss the advantages and notable functions that make these nanomaterials suitable for the design of new medicines; the biosafety of each material discussed in this article is also highlighted to provide a comprehensive understanding of their adjuvant attributes.

Nanodrug delivery in reversing multidrug resistance in cancer cells

Different mechanisms in cancer cells become resistant to one or more chemotherapeutics is known as multidrug resistance (MDR) which hinders chemotherapy efficacy. Potential factors for MDR includes enhanced drug detoxification, decreased drug uptake, increased intracellular nucleophiles levels, enhanced repair of drug induced DNA damage, overexpression of drug transporter such as P-glycoprotein(P-gp), multidrug resistance-associated proteins (MRP1, MRP2), and breast cancer resistance protein (BCRP). Currently nanoassemblies such as polymeric/solid lipid/inorganic/metal nanoparticles, quantum dots, dendrimers, liposomes, micelles has emerged as an innovative, effective, and promising platforms for treatment of drug resistant cancer cells. Nanocarriers have potential to improve drug therapeutic index, ability for multifunctionality, divert ABC-transporter mediated drug efflux mechanism and selective targeting to tumor cells, cancer stem cells, tumor initiating cells, or cancer microenvironment. Selective nanocarrier targeting to tumor overcomes dose-limiting side effects, lack of selectivity, tissue toxicity, limited drug access to tumor tissues, high drug doses, and emergence of multiple drug resistance with conventional or combination chemotherapy. Current review highlights various nanodrug delivery systems to overcome mechanism of MDR by neutralizing, evading, or exploiting the drug efflux pumps and those independent of drug efflux pump mechanism by silencing Bcl-2 and HIF1α gene expressions by siRNA and miRNA, modulating ceramide levels and targeting NF-κB. “Theragnostics” combining a cytotoxic agent, targeting moiety, chemosensitizing agent, and diagnostic imaging aid are highlighted as effective and innovative systems for tumor localization and overcoming MDR. Physical approaches such as combination of drug with thermal/ultrasound/photodynamic therapies to overcome MDR are focused. The review focuses on newer drug delivery systems developed to overcome MDR in cancer cell.

Nanodrug delivery systems: a promising technology for detection, diagnosis, and treatment of cancer

Nanotechnology has enabled the development of novel therapeutic and diagnostic strategies, such as advances in targeted drug delivery systems, versatile molecular imaging modalities, stimulus responsive components for fabrication, and potential theranostic agents in cancer therapy. Nanoparticle modifications such as conjugation with polyethylene glycol have been used to increase the duration of nanoparticles in blood circulation and reduce renal clearance rates. Such modifications to nanoparticle fabrication are the initial steps toward clinical translation of nanoparticles. Additionally, the development of targeted drug delivery systems has substantially contributed to the therapeutic efficacy of anti-cancer drugs and cancer gene therapies compared with nontargeted conventional delivery systems. Although multifunctional nanoparticles offer numerous advantages, their complex nature imparts challenges in reproducibility and concerns of toxicity. A thorough understanding of the biological behavior of nanoparticle systems is strongly warranted prior to testing such systems in a clinical setting. Translation of novel nanodrug delivery systems from the bench to the bedside will require a collective approach. The present review focuses on recent research efforts citing relevant examples of advanced nanodrug delivery and imaging systems developed for cancer therapy. Additionally, this review highlights the newest technologies such as microfluidics and biomimetics that can aid in the development and speedy translation of nanodrug delivery systems to the clinic.

Neuropilin-1-targeted gold nanoparticles enhance therapeutic efficacy of platinum(IV) drug for prostate cancer treatment

Platinum-based anticancer drugs such as cisplatin, oxaliplatin, and carboplatin are some of the most potent chemotherapeutic agents but have limited applications due to severe dose-limiting side effects and a tendency for cancer cells to rapidly develop resistance. The therapeutic index can be improved through use of nanocarrier systems to target cancer cells efficiently. We developed a unique strategy to deliver a platinum(IV) drug to prostate cancer cells by constructing glutathione-stabilized (Au@GSH) gold nanoparticles. Glutathione (GSH) has well-known antioxidant properties, which lead to cancer regression. Here, we exploit the advantages of both the antioxidant properties and high surface-area-to-volume ratio of Au@GSH NPs to demonstrate their potential for delivery of a platinum(IV) drug by targeting the neuropilin-1 receptor (Nrp-1). A lethal dose of a platinum(IV) drug functionalized with the Nrp-1-targeting peptide (CRGDK) was delivered specifically to prostate cancer cells in vitro. Targeted peptide ensures specific binding to the Nrp-1 receptor, leading to enhanced cellular uptake level and cell toxicity. The nanocarriers were themselves nontoxic, but exhibited high cytotoxicity and increased efficacy when functionalized with the targeting peptide and drug. The uptake of drug-loaded nanocarriers is dependent on the interaction with Nrp-1 in cell lines expressing high (PC-3) and low (DU-145) levels of Nrp-1, as confirmed through inductively coupled plasma mass spectrometry and confocal microscopy. The nanocarriers have effective anticancer activity, through upregulation of nuclear factor kappa-B (NF-κB) protein (p50 and p65) expression and activation of NF-κB-DNA-binding activity. Our preliminary investigations with platinum(IV)-functionalized gold nanoparticles along with a targeting peptide hold significant promise for future cancer treatment.

An overview of Brevinin superfamily: structure, function and clinical perspectives

Antimicrobial peptides are the backbone of first-line defense against various microorganisms in the animal kingdom. Thus, not surprisingly, they are gaining attention in the science and medical fields as a rich repository of new pro-drugs. Below, we focus our attention on the Brevinin family of anuran peptides. While most of them show strong antibacterial activities, some, e.g. Brevinin-2R, appear to be promising anticancer molecules, exhibiting better a therapeutic window than widely-use anticancer drugs like doxorubicin. We briefly introduce the field, followed by highlighting the promising therapeutic properties of Brevinins. Next, we provide information about the cloning and phylogenetic aspects of Brevinin genes. In the final paragraphs of this chapter, we discuss possible large-scale production methods of Brevinins, giving examples of some systems that are already in use. Towards the end, we discuss various means of modification of biologic properties of Brevinins, either by chemical modifications or by amino acid substitution and sequence rearrangements. In this context, also other unique properties of Brevinins are briefly mentioned. Finally, we discuss the future of the Brevinin field, particularly highlighting yet to be answered biologic questions, like for example presumed anti-viral and antitumor activities of Brevinin family members.

Target-selective phototherapy using a ligand-based photosensitizer for type 2 cannabinoid receptor

Phototherapy is a powerful, noninvasive approach for cancer treatment, with several agents currently in clinical use. Despite the progress and promise, most current phototherapy agents have serious side effects as they can lead to damage to healthy tissue, even when the photosensitizers are fused to targeting molecules due to nonspecific light activation of the unbound photosensitizer. To overcome these limitations, we developed a phototherapy agent that combines a functional ligand and a near infrared phthalocyanine dye. Our target is type 2 cannabinoid receptor (CB2R), considered an attractive therapeutic target for phototherapy given it is overexpressed by many types of cancers that are located at a surface or can be reached by an endoscope. We show that our CB2R-targeted phototherapy agent, IR700DX-mbc94, is specific for CB2R and effective only when bound to the target receptor. Overall, this opens up the opportunity for development of an alternative treatment option for CB2R-positive cancers.

Interactions at the silica-peptide interface: the influence of particle size and surface functionality

The variety of interactions that can occur at the silica/aqueous interface makes silica nanoparticles (SiNPs) attractive materials for technological applications. Despite their importance, interfacial interactions are not fully understood. In this contribution, we investigate the effect of (1) particle size and (2) surface functionalization on the adsorption of small biomolecular binders on SiNPs. Small silica binding peptides with different properties (charge, pI, and amino acid composition) were used as binders, while a range of fully characterized SiNPs of diameters ranging between 28 and 500 nm (pristine silica) and SiNPs of ca. 500 nm functionalized with cationic 3-aminopropyl groups and hydrophobic methyl groups was used as binding substrates. Adsorption and binding affinity were investigated by a fluorimetric assay at pH 7.4. A detailed characterization of the surface chemistry of the particles showed that the extent of surface functionalization on modified silica was well below monolayer coverage [by X-ray photoelectron spectroscopy (XPS), ca. 2 and 18 atomic % for the amino- and methyl-modified surfaces, respectively]. Although peptide binding is generally moderated by the physicochemical characteristics of the adsorbing peptide, the introduction of such a small degree of functionality onto silica particles was sufficient to produce drastic changes in adsorption at the silica/aqueous interface. In addition, an increase in peptide adsorption with an increasing particle size, independent of the nature and properties of the peptide, was observed. This particle size effect is attributed to a shift of the dominant binding mechanism toward electrostatic interactions on larger SiNPs. The data presented demonstrate that particle size and surface functionality are both parameters that can substantially influence (bio)molecule uptake via modulation or selection of specific binding modes at the silica/peptide interface. These results are applicable to the design and development of interfaces with specific adsorption/affinity response for biomedical applications, where uptake is important, such as drug delivery. Further, they provide important insights on how peptide affinity and selection during biopanning can be determined by small changes in surface chemistry of the surface of a target that can, in some instances, be associated with the presence of impurities.

In vitro activity studies of hyperthermal near-infrared nanoGUMBOS in MDA-MB-231 breast cancer cells

Nanoparticles devised entirely of ionic liquid-like materials called GUMBOS created a localized hyperthermal effect within breast cancer cells concurrent with near-infrared laser excitation.

Nanoparticles targeting mechanisms in cancer therapy: current limitations and emerging solutions

It has been more than one century since Paul Ehrlich spoke about the idea of targeting specific molecules in the cell when he coined the ‘Magic Bullet‘ principle. In most occasions, we seek new pharmacodynamic models for therapy, but nanoparticles provide a chance to modify the already existing pharmacokinetics of drugs to meet needed pharmacodynamic models. In the scope of ‘nanoscale‘, every entity has different characters, and no general rules control pharmacokinetics of nanoparticulate drugs as new physical and physicochemical properties are added to equations. However, such remarkable drug models are still quite far from achieving their potential in clinical application. Among the major obstacles is that most available results in nanoparticles targeting rely upon in vitro and animal models that do not match the tumor environment characteristics in humans. This Review discusses the concept of targeting tumor cells with nanoparticles, the limitations that lead to its incomplete application in clinical practice along with some of the promising solutions to such limitations.

Recombinant bacteriophages as gold binding bio-templates

Bacteriophages are nano-sized virion particles infecting bacteria. In this study, it is shown that metal binding properties of filamentous fd-bacteriophages can be enhanced by genetic engineering. Quartz crystal microbalance (QCM) analyses, UV-vis absorption spectra measurements and scanning electron microscopy (SEM) imaging revealed that expression of MMM short amino acid sequence on major coat protein p8 facilitates recombinant MMM-phage binding to Au surfaces and nanoparticles (NPs) via gold-sulfur (AuS) interaction. Electroless deposition of Au particles on phage assemblies was investigated upon chemical reduction reaction with NaBH4 at different HAuCl4 precursor concentrations. Energy dispersive X-ray spectroscopy (EDX) measurements confirmed the presence of Au on both AuNP decorated and chemically metallized phage structures. Further studies on patterning and controlled immobilization of recombinant bacteriophages on specific surfaces may contribute to bio-templated nanowire development field and biosensor application studies.

Microscopic Studies of Various Sizes of Gold Nanoparticles and Their Cellular Localizations

Gold nanoparticles (GNPs) are widely used in biological and clinical applications due to their favorable chemical and optical properties. GNPs can be used for drug delivery to targeted cells. In addition, GNPs serve as ideal probes for biological and cell imaging applications. Recent studies indicate that the size diversity of GNPs plays an important role in targeting cellular components for biomedical applications. In this study, we conducted a series of studies using different sizes of gold nanoparticles, including 3, 10, 25, and 50 nm, to determine the effect of size variations on their intracellular localizations. Our cytotoxicity studies of GNPs into the HEp-2 cells using MTT assay indicated that 3 nm GNPs possess the highest toxicity. We exposed HEp-2 cells with various sizes of gold nanoparticles for different time intervals (1, 2, 4, 12, and 24 h) followed by imaging using scanning electron microscope (SEM) and atomic force microscope (AFM). Our SEM and AFM results showed that, after 1 hr incubation, 3 and 10 nm gold nanoparticles entered the nucleus, whereas 25 and 50 nm particles accumulated around the nucleus. As the time of exposure increased, GNPs entered the cells and accumulated in the cytosol and nucleus based solely on their sizes.

Gold nanoparticle-M2e conjugate coformulated with CpG induces protective immunity against influenza A virus

AIM

This study aimed to develop a novel influenza A vaccine by conjugating the highly conserved extracellular region of the matrix 2 protein (M2e) of influenza A virus to gold nanoparticles (AuNPs) and to test the vaccine in a mouse influenza challenge model.

MATERIALS & METHODS

Citrate-reduced AuNPs (diameter: 12 nm) were synthesized, and characterized by transmission electron microscopy and dynamic light scattering. M2e was conjugated to AuNPs through thiol-gold interactions to form M2e-AuNP conjugates. Particle stability was confirmed by UV-visible spectra, and M2e conjugation was further characterized by x-ray photoelectron spectroscopy. Mice were immunized with M2e-AuNPs with or without CpG (cytosine-guanine rich oligonucleotide) as an adjuvant with appropriate control groups. Sera was collected and M2e-specific immunoglobulin (IgG) was measured, and immunized mice were challenged with PR8-H1N1 influenza virus.

RESULTS

M2e-capped AuNPs could be lyophilized and stably resuspended in water. Intranasal vaccination of mice with M2e-AuNP conjugates induced M2e-specific IgG serum antibodies, which significantly increased upon addition of soluble CpG as adjuvant. Upon challenge with lethal PR8, mice vaccinated with M2e-AuNP conjugates were only partially protected, while mice that received soluble CpG as adjuvant in addition to M2e-AuNP were fully protected.

CONCLUSION

Overall, this study demonstrates the potential of using the M2e-AuNP conjugates with CpG as an adjuvant as a platform for developing an influenza A vaccine.

Functionalized nanoscale micelles improve drug delivery for cancer therapy in vitro and in vivo

Poor penetration of therapeutic drugs into tumors is a major challenge in anticancer therapy, especially in solid tumors, leading to reduced therapeutic efficacy in vivo. In the study, we used a new tumor-penetrating peptide, CRGDK, to conjugate onto the surface of doxorubicin encapsulated nanoscale micelles. The CRGDK peptide triggered specific binding to neuropilin-1, leading to enhanced cellular uptake and cytotoxicity in vitro and highly accumulation and penetration in the tumors in vivo.

Biosafety and bioapplication of nanomaterials by designing protein-nanoparticle interactions

The protein-nanoparticle (NP) interface is a current frontier of multiple disciplines, full of challenges and opportunities. The unique behaviors of nanomaterials (NMs) bring many exciting applications, and also raise safety concerns. Beyond bioapplications, various NMs could also enter human bodies from the environment. When entering human bodies, NPs interact with various biomolecules, especially proteins, forming a protein corona. This protein-NP complex is what the biosystems 'see' and 'respond to'. Therefore, understanding how NPs interact with proteins is crucial for both bioapplications and the biosafety of NMs. In this review, the current understanding of protein-NP interactions is summarized, including the theoretical background, experimental results, and computational progresses. Guidelines for improving bioapplication performance and reducing the potential biosafety hazard of NMs by designing the protein-NP interactions are discussed, along with future directions and challenges in this exciting field.

Remotely Triggered Drug Release from Gold Nanoparticle-based Systems

Nanoparticles are attractive drug carriers that can combine drug molecules and targeting moieties in order to improve treatment efficacy and reduce unwanted side effects. In addition, activatable nanoparticles may enable drug release in the target sites at accurate timings or conditions, in which drug discharge can be controlled by specific stimuli. Especially, gold nanoparticles provide a great opportunity as drug carriers because of the following advantageous features: i) simple formulation with various sizes and shapes and non-toxicity; ii) easy incorporation of targeting molecules, drugs or other therapeutic molecules on them; iii) triggered drug release by means of external or internal stimuli. In this chapter, we describe relevant examples of the preparation techniques and the performance of various types of gold nanoparticles for drug delivery as well as theranostics.

Influence of the surface coating on the cytotoxicity, genotoxicity and uptake of gold nanoparticles in human HepG2 cells

The toxicological profile of gold nanoparticles (AuNPs) remains controversial. Significant efforts to develop surface coatings to improve biocompatibility have been carried out. In vivo biodistribution studies have shown that the liver is a target for AuNPs accumulation. Therefore, we investigated the effects induced by ~20 nm spherical AuNPs (0-200 μM Au) with two surface coatings, citrate (Cit) compared with 11-mercaptoundecanoic acid (11-MUA), in human liver HepG2 cells. Cytotoxicity was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and lactate dehydrogenase (LDH) release assays after 24 to 72 h of incubation. DNA damage was assessed by the comet assay, 24 h after incubation with the capped AuNPs. Uptake and subcellular distribution of the tested AuNPs was evaluated by quantifying the gold intracellular content by graphite furnace atomic absorption spectrometry (GFAAS) and transmission electron microscopy (TEM), respectively. The obtained results indicate that both differently coated AuNPs did not induce significant cytotoxicity. An inverse concentration-dependent increase in comet tail intensity and tail moment was observed in Cit-AuNPs- but not in MUA-AuNPs-exposed cells. Both AuNPs were internalized in a concentration-dependent manner. However, no differences were found in the extent of the internalization between the two types of NPs. Electron-dense deposits of agglomerates of Cit- and MUA-AuNPs were observed either inside endosomes or in the intercellular spaces. In spite of the absence of cytotoxicity, DNA damage was observed after exposure to the lower concentrations of Cit- but not to MUA-AuNPs. Thus, our data supports the importance of the surface properties to increase the biocompatibility and safety of AuNPs.

In vitro antitumor assessments of peptide nanocomplexes on Dalton's lymphoma ascites tumor model

This research work reports the in vitro antitumor personality of few novel peptide nanocomplexes synthesized via a phase-assisted, modified Brust-Schiffrin methodology. Here, a series of metallo(copper, cobalt, nickel and zinc) nanocomplexes engineered with a pre-prepared peptide [N,N'-(1,2-ethylene)-bis-hippuricamide] have been synthesized for damaging the Dalton's lymphoma ascites tumor model. All the peptide nanocomplexes are spectrally, thermally and morphologically examined. The peptide bound zinc and cobalt nanocomplexes deliver excellent antitumor behavior against both the animal and human cancer cell lines, which has been pre-documented by their efficient DNA damaging skills under physiological conditions. Additionally, all the nanocomplexes are evaluated for the inhibition of microbial augmentation against few fungal and bacterial strains. The above results demonstrate that, a consecutive development of these kinds of peptide nanocomplexes may exemplify their uniqueness in biomedical applications as useful molecular-level devices.

Gold-containing bioactive glasses: a solid-state synthesis to produce alternative biomaterials for bone implantations

A new melted bioactive system containing gold nanoparticles (AuNPs) was prepared exploiting a post-synthesis thermal treatment that allows one to modify crystal phases and nature, shape and distribution of the gold species in the glass-ceramic matrix as evidenced by UV-visible spectroscopy, transmission electron microscopy and powder X-ray diffraction analysis. In human MG-63 osteoblasts the presence of Au(n)(+) species caused an increase of lactate dehydrogenase leakage and malonyldialdehyde production, whereas Hench's Bioglass HAu-600-17 containing only AuNPs did not cause any effect. In addition, HAu-600-17 caused in vitro hydroxyapatite formation and an increase of specific surface area with a controlled release of gold species; this material is then suitable to be used as a model system for the controlled delivery of nanoparticles.

Multifunctional gold nanoparticles for diagnosis and therapy of disease

Gold nanoparticles (AuNPs) have a number of physical properties that make them appealing for medical applications. For example, the attenuation of X-rays by gold nanoparticles has led to their use in computed tomography imaging and as adjuvants for radiotherapy. AuNPs have numerous other applications in imaging, therapy and diagnostic systems. The advanced state of synthetic chemistry of gold nanoparticles offers precise control over physicochemical and optical properties. Furthermore gold cores are inert and are considered to be biocompatible and nontoxic. The surface of gold nanoparticles can easily be modified for a specific application, and ligands for targeting, drugs or biocompatible coatings can be introduced. AuNPs can be incorporated into larger structures such as polymeric nanoparticles or liposomes that deliver large payloads for enhanced diagnostic applications, efficiently encapsulate drugs for concurrent therapy or add additional imaging labels. This array of features has led to the aforementioned applications in biomedical fields, but more recently in approaches where multifunctional gold nanoparticles are used for multiple methods, such as concurrent diagnosis and therapy, so-called theranostics. This review covers basic principles and recent findings in gold nanoparticle applications for imaging, therapy and diagnostics, with a focus on reports of multifunctional AuNPs.

Superior penetration and retention behavior of 50 nm gold nanoparticles in tumors

Nanoparticles offer potential as drug delivery systems for chemotherapeutics based on certain advantages of molecular drugs. In this study, we report that particle size exerts great influence on the penetration and retention behavior of nanoparticles entering tumors. On comparing gold-coated Au@tiopronin nanoparticles that were prepared with identical coating and surface properties, we found that 50 nanoparticles were more effective in all in vitro, ex vivo, and in vivo assays conducted using MCF-7 breast cells as a model system. Beyond superior penetration in cultured cell monolayers, 50 nm Au@tiopronin nanoparticles also penetrated more deeply into tumor spheroids ex vivo and accumulated more effectively in tumor xenografts in vivo after a single intravenous dose. In contrast, larger gold-coated nanoparticles were primarily localized in the periphery of the tumor spheroid and around blood vessels, hindering deep penetration into tumors. We found multicellular spheroids to offer a simple ex vivo tumor model to simulate tumor tissue for screening the nanoparticle penetration behavior. Taken together, our findings define an optimal smaller size for nanoparticles that maximizes their effective accumulation in tumor tissue.

Targeting VEGF signalling via the neuropilin co-receptor

The blockade of tumour vascularisation and angiogenesis continues to be a focus for drug development in oncology and other pathologies. Historically, targeting vascular endothelial growth factor (VEGF) activity and its association with VEGF receptors (VEGFRs) has represented the most promising line of attack. More recently, the recognition that VEGFR co-receptors, neuropilin-1 and -2 (NRP1 and NRP2), are also engaged by specific VEGF isoforms in tandem with the VEGFRs has expanded the landscape for the development of modulators of VEGF-dependent signalling. Here, we review the recent structural characterisation of VEGF interactions with NRP subdomains and the impact this has had on drug development activity in this area.

Recent advances in benefits and hazards of engineered nanoparticles

Over recent decades, engineered nanoparticles are increasingly produced as the result of the rapid development in nanotechnology. They are currently used in a wide range of industrial and public sectors including healthcare, agriculture, transport, energy, materials, and information and communication technologies. As the result, an increasing concern has been raised over the potential impacts of engineered nanoparticles to human health. In the light of this, it is the purpose of the present review to discuss: (1) novel properties of engineered nanoparticles particularly in biomedical sciences, (2) most recently reported adverse effects of manufactured nanoparticles on human health and (3) different aspects of toxicological risk assessment of these nanoparticles.

Gold nanoparticles: emerging paradigm for targeted drug delivery system

The application of nanotechnology in medicine, known as nanomedicine, has introduced a plethora of nanoparticles of variable chemistry and design considerations for cancer diagnosis and treatment. One of the most important field is the design and development of pharmaceutical drugs, based on targeted drug delivery system (TDDS). Being inspired by physio-chemical properties of nanoparticles, TDDS are designed to safely reach their targets and specifically release their cargo at the site of disease for enhanced therapeutic effects, thereby increasing the drug tissue bioavailability. Nanoparticles have the advantage of targeting cancer by simply being accumulated and entrapped in cancer cells. However, even after rapid growth of nanotechnology in nanomedicine, designing an effective targeted drug delivery system is still a challenging task. In this review, we reveal the recent advances in drug delivery approach with a particular focus on gold nanoparticles. We seek to expound on how these nanomaterials communicate in the complex environment to reach the target site, and how to design the effective TDDS for complex environments and simultaneously monitor the toxicity on the basis of designing such delivery complexes. Hence, this review will shed light on the research, opportunities and challenges for engineering nanomaterials with cancer biology and medicine to develop effective TDDS for treatment of cancer.

Cytotoxic effects of gold nanoparticles: a multiparametric study

The in vitro labeling of therapeutic cells with nanoparticles (NPs) is becoming more and more common, but concerns about the possible effects of the NPs on the cultured cells are also increasing. In the present work, we evaluate the effects of poly(methacrylic acid)-coated 4 nm diameter Au NPs on a variety of sensitive and therapeutically interesting cell types (C17.2 neural progenitor cells, human umbilical vein endothelial cells, and PC12 rat pheochromocytoma cells) using a multiparametric approach. Using various NP concentrations and incubation times, we performed a stepwise analysis of the NP effects on cell viability, reactive oxygen species, cell morphology, cytoskeleton architecture, and cell functionality. The data show that higher NP concentrations (200 nM) reduce cell viability mostly through induction of reactive oxygen species, which was significantly induced at concentrations of 50 nM Au NPs or higher. At these concentrations, both actin and tubulin cytoskeleton were deformed and resulted in reduced cell proliferation and cellular differentiation. In terms of cell functionality, the NPs significantly impeded neurite outgrowth of PC12 cells up to 20 nM concentrations. At 10 nM, no significant effects on any cellular parameter could be observed. These data highlight the importance of using multiple assays to cover the broad spectrum of cell-NP interactions and to determine safe NP concentrations and put forward the described protocol as a possible template for future cell-NP interaction studies under comparable and standardized conditions.

Synthesis, characterization, and direct intracellular imaging of ultrasmall and uniform glutathione-coated gold nanoparticles

Gold nanoparticles (AuNPs) with core sizes below 2 nm and compact ligand shells constitute versatile platforms for the development of novel reagents in nanomedicine. Due to their ultrasmall size, these AuNPs are especially attractive in applications requiring delivery to crowded intracellular spaces in the cytosol and nucleus. For eventual use in vivo, ultrasmall AuNPs should ideally be monodisperse, since small variations in size may affect how they interact with cells and how they behave in the body. Here we report the synthesis of ultrasmall, uniform 144-atom AuNPs protected by p-mercaptobenzoic acid followed by ligand exchange with glutathione (GSH). Quantitative scanning transmission electron microscopy (STEM) reveals that the resulting GSH-coated nanoparticles (Au(GSH)) have a uniform mass distribution with cores that contain 134 gold atoms on average. Particle size dispersity is analyzed by analytical ultracentrifugation, giving a narrow distribution of apparent hydrodynamic diameter of 4.0 ± 0.6 nm. To evaluate the nanoparticles' intracellular fate, the cell-penetrating peptide TAT is attached noncovalently to Au(GSH), which is confirmed by fluorescence quenching and isothermal titration calorimetry. HeLa cells are then incubated with both Au(GSH) and the Au(GSH)-TAT complex, and imaged without silver enhancement of the AuNPs in unstained thin sections by STEM. This imaging approach enables unbiased detection and quantification of individual ultrasmall nanoparticles and aggregates in the cytoplasm and nucleus of the cells.

Magnetoferritin nanoparticles for targeting and visualizing tumour tissues

Engineered nanoparticles have been used to provide diagnostic, therapeutic and prognostic information about the status of disease. Nanoparticles developed for these purposes are typically modified with targeting ligands (such as antibodies, peptides or small molecules) or contrast agents using complicated processes and expensive reagents. Moreover, this approach can lead to an excess of ligands on the nanoparticle surface, and this causes non-specific binding and aggregation of nanoparticles, which decreases detection sensitivity. Here, we show that magnetoferritin nanoparticles (M-HFn) can be used to target and visualize tumour tissues without the use of any targeting ligands or contrast agents. Iron oxide nanoparticles are encapsulated inside a recombinant human heavy-chain ferritin (HFn) protein shell, which binds to tumour cells that overexpress transferrin receptor 1 (TfR1). The iron oxide core catalyses the oxidation of peroxidase substrates in the presence of hydrogen peroxide to produce a colour reaction that is used to visualize tumour tissues. We examined 474 clinical specimens from patients with nine types of cancer and verified that these nanoparticles can distinguish cancerous cells from normal cells with a sensitivity of 98% and specificity of 95%.

Cell cycle arrest and apoptosis of OVCAR-3 and MCF-7 cells induced by co-immobilized TNF-α plus IFN-γ on polystyrene and the role of p53 activation

The aim of this study is to reveal the biological mechanism for high anti-cancer efficiency of co-immobilized TNF-α plus IFN-γ polymeric drug (co-immobilized drug) in mediating two gynecologic cancer cell lines: MCF-7 and OVCAR-3. The co-immobilized drug is prepared by mixing 10 ng/ml TNF-α plus 10 ng/ml IFN-γ which are then photo-immobilized onto cell culture polystyrene plates. The drug compositions and microstructures are characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The MCF-7 and OVCAR-3 cell cycle arrest and programmed cell death are checked by flow cytometry, and the expression of p53 is probed by immunofluorescence staining. The phosphorylation sites of the p53 regulation and the apoptosis key protein expressions of caspase 3, 8 and 9 are detected by western blot assay. Our data show that, in case of short treatment time (48 h) at low cytokine concentrations (20 ng/ml), the co-immobilized drug demonstrates visible effects in comparison with the treatment using TNF-α plus IFN-γ freely attached on the polymeric plate (free drug). It is revealed that the co-immobilized drug leads to significant cell arrest in the S phase or G(1) and G(2) phase and offer high efficiency in mediating a caspase-dependent apoptosis via p53 transcriptional regulation. Moreover, upon the treatment by the co-immobilized drug, the two gynecologic cancer cell lines show different phosphorylation sites of p53 and then different caspase-dependent apoptosis pathways. The present work sheds deep insights into the p53 regulation mechanism responsible for the high anti-cancer efficiency of the co-immobilized TNF-α plus IFN-γ polymeric drug against MCF-7 and OVCAR-3.

Size-dependent localization and penetration of ultrasmall gold nanoparticles in cancer cells, multicellular spheroids, and tumors in vivo

This work demonstrated that ultrasmall gold nanoparticles (AuNPs) smaller than 10 nm display unique advantages over nanoparticles larger than 10 nm in terms of localization to, and penetration of, breast cancer cells, multicellular tumor spheroids, and tumors in mice. Au@tiopronin nanoparticles that have tunable sizes from 2 to 15 nm with identical surface coatings of tiopronin and charge were successfully prepared. For monolayer cells, the smaller the Au@tiopronin NPs, the more AuNPs found in each cell. In addition, the accumulation of Au NPs in the ex vivo tumor model was size-dependent: smaller AuNPs were able to penetrate deeply into tumor spheroids, whereas 15 nm nanoparticles were not. Owing to their ultrasmall nanostructure, 2 and 6 nm nanoparticles showed high levels of accumulation in tumor tissue in mice after a single intravenous injection. Surprisingly, both 2 and 6 nm Au@tiopronin nanoparticles were distributed throughout the cytoplasm and nucleus of cancer cells in vitro and in vivo, whereas 15 nm Au@tiopronin nanoparticles were found only in the cytoplasm, where they formed aggregates. The ex vivo multicellular spheroid proved to be a good model to simulate in vivo tumor tissue and evaluate nanoparticle penetration behavior. This work gives important insights into the design and functionalization of nanoparticles to achieve high levels of accumulation in tumors.