The effect of ligand composition on the in vivo fate of multidentate poly(ethylene glycol) modified gold nanoparticles

The Commonly Used Stabilizers for Phytochemical-Based Nanoparticles: Stabilization Effects, Mechanisms, and Applications

Phytochemicals, such as resveratrol, curcumin, and quercetin, have many benefits for health, but most of them have a low bioavailability due to their poor water solubility and stability, quick metabolism, and clearance, which restricts the scope of their potential applications. To overcome these issues, different types of nanoparticles (NPs), especially biocompatible and biodegradable NPs, have been developed. NPs can carry phytochemicals and increase their solubility, stability, target specificity, and oral bioavailability. However, NPs are prone to irreversible aggregation, which leads to NP instability and loss of functions. To remedy this shortcoming, stabilizers like polymers and surfactants are incorporated on NPs. Stabilizers not only increase the stability of NPs, but also improve their characteristics. The current review focused on discussing the state of the art in research on synthesizing phytochemical-based NPs and their commonly employed stabilizers. Furthermore, stabilizers in these NPs were also discussed in terms of their applications, effects, and underlying mechanisms. This review aimed to provide more references for developing stabilizers and NPs for future research.

In vivo and In vitro properties evaluation of curcumin loaded MgO doped 3D printed TCP scaffolds

The lack of site-specific chemotherapeutic agents to treat bone malignancy throws a significant challenge in the design of a delivery vehicle. The major scientific question posed in this study is, can we utilize curcumin-loaded magnesium oxide (MgO) doped 3D printed tricalcium phosphate (TCP) bone grafts as a localized delivery system that improves early stage in vivo osseointegration and in vitro chemoprevention, antibacterial properties? We have utilized curcumin as an alternative natural chemopreventive agent for bone cancer-specific delivery after direct incorporation on the 3D printed tricalcium phosphate (TCP) bone grafts. The addition of MgO as a dopant to TCP leads to ∼1.3 times enhancement in compressive strength. The designed drug delivery system shows up to ∼22% curcumin release in a physiological pH of 7.4 after 30 days. The presence of curcumin leads to up to ∼8.5 times reduction in osteosarcoma viability. In vitro results indicate that these scaffolds significantly enhance bone-forming osteoblast cells while reducing the bone-resorbing osteoclast cells. The in vivo rat distal femur model surgery followed by histological assessment with H&E, vWF, and Movat pentachrome staining results show that the designed scaffolds lead to new bone formation (up to ∼2.5 times higher than the control) after successful implantation. The presence of MgO and curcumin results in up to ∼71% antibacterial efficacy against osteomyelitis causing S. aureus. These 3D printed osteogenic and chemopreventive scaffolds can be utilized in patient-specific low load-bearing defect sites.

Surface engineering strategies of gold nanomaterials and their applications in biomedicine and detection

Gold nanomaterials have potential applications in biosensors and biomedicine due to their controllable synthesis steps, high biocompatibility, low toxicity and easy surface modification. However, there are still various limitations including low water solubility and stability, which greatly affect their applications. In addition, some synthetic methods are very complicated and costly. Therefore, huge efforts have been made to improve their properties. This review mainly introduces the strategies for surface modification of gold nanomaterials, such as amines, biological small molecules and organic small molecules as well as the biological applications of these functionalized AuNPs. We aim to provide effective ideas for better functionalization of gold nanomaterials in the future.

Advances in the application of gold nanoparticles in bone tissue engineering

The materials used in bone tissue engineering (BTE) have been advancing with each passing day. With the continuous development of nanomedicine, gold nanoparticles (GNPs), which are easy to be synthesized and functionalized, have attracted increasing attention. Recent years have witnessed this amazing material, i.e., GNPs characterized with large surface area to volume ratio, biocompatibility, medical imaging property, hypotoxicity, translocation into the cells, high reactivity, and other properties, perform distinct functions in BTE. However, the low stability of GNPs in the biotic environment makes them in the requirements of modification or recombination before being used. After being combined with the advantages of other materials, the structures of GNPs have exhibited great potential in stem cells, scaffolds, delivery systems, medical imaging, and other aspects. This review will focus on the advances in the application of GNPs after modification or recombination with other materials to BTE.

Improved Efficacy and Reduced Toxicity Using a Custom-Designed Irinotecan-Delivering Silicasome for Orthotopic Colon Cancer

Irinotecan is a key chemotherapeutic agent for the treatment of colorectal (CRC) and pancreatic (PDAC) cancer. Because of a high incidence of bone marrow and gastrointestinal (GI) toxicity, Onivyde (a liposome) was introduced to provide encapsulated irinotecan (Ir) delivery in PDAC patients. While there is an ongoing clinical trial (NCT02551991) to investigate the use of Onivyde as a first-line option to replace irinotecan in FOLFIRINOX, the liposomal formulation is currently prescribed as a second-line treatment option (in combination with 5-fluorouracil and leucovorin) for patients with metastatic PDAC who failed gemcitabine therapy. However, the toxicity of Onivyde remains a concern that needs to be addressed for use in CRC as well. Our goal was to custom design a mesoporous silica nanoparticle (MSNP) carrier for encapsulated irinotecan delivery in a robust CRC model. This was achieved by developing an orthotopic tumor chunk model in immunocompetent mice. With a view to increase the production volume and to expand the disease applications, the carrier design was improved by using an ethanol exchange method for coating of a supported lipid bilayer (LB) that entraps a protonating agent. The encapsulated protonating agent was subsequently used for remote loading of irinotecan. The excellent irinotecan loading capacity and stability of the LB-coated MSNP carrier, also known as a "silicasome", previously showed improved efficacy and reduced toxicity when compared to an in-house liposomal carrier in a PDAC model. Intravenous injection of the silicasomes in a well-developed orthotopic colon cancer model in mice demonstrated improved pharmacokinetics and tumor drug content over free drug and Onivyde. Moreover, improved drug delivery was accompanied by substantially improved efficacy, increased survival, and reduced bone marrow and GI toxicity compared to the free drug and Onivyde. We also confirmed that the custom-designed irinotecan silicasomes outperform Onivyde in an orthotopic PDAC model. In summary, the Ir-silicasome appears to be promising as a treatment option for CRC in humans based on improved efficacy and the carrier's favorable safety profile.

Nanomaterials as photothermal therapeutic agents

Curing cancer has been one of the greatest conundrums in the modern medical field. To reduce side-effects associated with the traditional cancer therapy such as radiotherapy and chemotherapy, photothermal therapy (PTT) has been recognized as one of the most promising treatments for cancer over recent years. PTT relies on ablation agents such as nanomaterials with a photothermal effect, for converting light into heat. In this way, elevated temperature could kill cancer cells while avoiding significant side effects on normal cells. This theory works because normal cells have a higher heat tolerance than cancer cells. Thus, nanomaterials with photothermal effects have attracted enormous attention due to their selectivity and non-invasive attributes. This review article summarizes the current status of employing nanomaterials with photothermal effects for anti-cancer treatment. Mechanisms of the photothermal effect and various factors affecting photothermal performance will be discussed. Efficient and selective PTT is believed to play an increasingly prominent role in cancer treatment. Moreover, merging PTT with other methods of cancer therapies is also discussed as a future trend.

Development of a systematic method to assess similarity between nanomaterials for human hazard evaluation purposes - lessons learnt

Within the EU FP-7 GUIDEnano project, a methodology was developed to systematically quantify the similarity between a nanomaterial (NM) that has been tested in toxicity studies and the NM for which risk needs to be evaluated, for the purpose of extrapolating toxicity data between the two materials. The methodology is a first attempt to use current knowledge on NM property-hazard relationships to develop a series of pragmatic and systematic rules for assessing NM similarity. Moreover, the methodology takes into account the practical feasibility, in that it is based on generally available NM characterization information. In addition to presenting this methodology, the lessons learnt and the challenges faced during its development are reported here. We conclude that there is a large gap between the information that is ideally needed and its application to real cases. The current database on property-hazard relationships is still very limited, which hinders the agreement on the key NM properties constituting the basis of the similarity assessment and the development of associated science-based and unequivocal rules. Currently, one of the most challenging NM properties to systematically assess in terms of similarity between two NMs is surface coating and functionalization, which lacks standardized parameters for description and characterization methodology. Standardization of characterization methods that lead to quantitative, unambiguous, and measurable parameters describing NM properties are necessary in order to build a sufficiently robust property-hazard database that allows for evidence-based refinement of our methodology, or any other attempt to systematically assess the similarity of NMs.

Enhanced uptake in 2D- and 3D- lung cancer cell models of redox responsive PEGylated nanoparticles with sensitivity to reducing extra- and intracellular environments

In the treatment of lung cancer, there is an urgent need of innovative medicines to optimize pharmacological responses of conventional chemotherapeutics while attenuating side effects. Here, we have exploited some relatively unexplored subtle differences in reduction potential, associated with cancer cell microenvironments in addition to the well-known changes in intracellular redox environment. We report the synthesis and application of novel redox-responsive PLGA (poly(lactic-co-glycolic acid)) -PEG (polyethylene glycol) nanoparticles (RR-NPs) programmed to change surface properties when entering tumor microenvironments, thus enhancing cell internalization of the particles and their drug cargo. The new co-polymers, in which PEG and PLGA were linked by 'anchiomeric effector' dithiylethanoate esters, were synthesized by a combination of ring-opening polymerization and Michael addition reactions and employed to prepare NPs. Non redox-responsive nanoparticles (nRR-NPs) based on related PLGA-PEG copolymers were also prepared as comparators. Spherical NPs of around 120 nm diameter with a low polydispersity index and negative zeta potential as well as good drug loading of docetaxel were obtained. The NPs showed prolonged stability in relevant simulated biological fluids and a high ability to penetrate an artificial mucus layer due to the presence of the external PEG coating. Stability, FRET and drug release studies in conditions simulating intracellular reductive environments demonstrated a fast disassembly of the external shell of the NPs, thus triggering on-demand drug release. FACS measurements and confocal microscopy showed increased and faster uptake of RR-NPs in both 2D- and 3D- cell culture models of lung cancer compared to nRR-NPs. In particular, the 'designed-in' reductive instability of RR-NPs in conditioned cell media, the fast PEG release in the extracellular compartment, as well as a diminution of uptake rate in control experiments where extracellular thiols were neutralized, suggested a partial extracellular release of the PEG fringe that promoted rapid internalization of the residual NPs into cells. Taken together, these results provide further evidence of the effectiveness of PEGylated reducible nanocarriers to permeate mucus layer barriers, and establish a new means to enhance cancer cell uptake of drug carriers by extra-and intra-cellular cleavage of protein- and cell-shielding hydrophilic blocks.

Hydrophobic and Hydrophilic Au and Ag Nanoparticles. Breakthroughs and Perspectives

This review provides a broad look on the recent investigations on the synthesis, characterization and physico-chemical properties of noble metal nanoparticles, mainly gold and silver nanoparticles, stabilized with ligands of different chemical nature. A comprehensive review of the available literature in this field may be far too large and only some selected representative examples will be reported here, together with some recent achievements from our group, that will be discussed in more detail. Many efforts in finding synthetic routes have been performed so far to achieve metal nanoparticles with well-defined size, morphology and stability in different environments, to match the large variety of applications that can be foreseen for these materials. In particular, the synthesis and stabilization of gold and silver nanoparticles together with their properties in different emerging fields of nanomedicine, optics and sensors are reviewed and briefly commented.

Gold nanoparticles enlighten the future of cancer theranostics

Development of multifunctional nanomaterials, one of the most interesting and advanced research areas in the field of nanotechnology, is anticipated to revolutionize cancer diagnosis and treatment. Gold nanoparticles (AuNPs) are now being widely utilized in bio-imaging and phototherapy due to their tunable and highly sensitive optical and electronic properties (the surface plasmon resonance). As a new concept, termed "theranostics," multifunctional AuNPs may contain diagnostic and therapeutic functions that can be integrated into one system, thereby simultaneously facilitating diagnosis and therapy and monitoring therapeutic responses. In this review, the important properties of AuNPs relevant to diagnostic and phototherapeutic applications such as structure, shape, optics, and surface chemistry are described. Barriers for translational development of theranostic AuNPs and recent advances in the application of AuNPs for cancer diagnosis, photothermal, and photodynamic therapy are discussed.

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.

Colloidal Stability of Silk Fibroin Nanoparticles Coated with Cationic Polymer for Effective Drug Delivery

Generally, silk fibroin nanoparticles (SFNPs) are great candidates to deliver drugs or other bioactive substances in vivo. However, their further applications are largely limited by the low colloidal stability of SFNPs, as they tend to aggregate in biological media. To address this issue, SFNP composite materials with a core-shell structure (CS-SFNPs) were fabricated by coating SFNPs with four different selected cationic polymers, glycol chitosan, N,N,N-trimethyl chitosan, polyethylenimine, and PEGylated polyethylenimine, through electrostatic interaction. According to the DLS and NTA results, compared with the bare SFNPs, the CS-SFNPs showed much higher colloidal stability in biological media. When treated with human cervical carcinoma (HeLa) cells, the CS-SFNPs were efficiently internalized and accumulated in lysosome; and when loaded with an anticancer drug, DOX, the CS-SFNPs also showed higher cytotoxicity against HeLa cells. Our results suggest that the fabricated CS-SFNPs with desirable colloidal stability in biological media have the potential to be employed as drug carriers for the anticancer drug delivery system.

A physiologically based pharmacokinetic model for polyethylene glycol-coated gold nanoparticles of different sizes in adult mice

Nanoparticles (NPs) are widely used in various fields of nanomedicine. A systematic understanding of NP pharmacokinetics is crucial in their design, applications, and risk assessment. In order to integrate available experimental information and to gain insights into NP pharmacokinetics, a membrane-limited physiologically based pharmacokinetic (PBPK) model for polyethylene glycol-coated gold (Au) NPs (PEG-coated AuNPs) was developed in mice. The model described endocytosis of the NPs in the liver, spleen, kidneys, and lungs and was calibrated using data from mice that were intravenously injected with 0.85 mg/kg 13 nm and 100 nm PEG-coated AuNPs. The model adequately predicted multiple external datasets for PEG-coated AuNPs of similar sizes (13-20 nm; 80-100 nm), indicating reliable predictive capability in suitable size ranges. Simulation results suggest that endocytosis of NPs is time and size dependent, i.e. endocytosis of larger NPs occurs immediately and predominately from the blood, whereas smaller NPs can diffuse through the capillary wall and their endocytosis appears mainly from the tissue with a 10-h delay, which may be the primary mechanism responsible for the reported size-dependent pharmacokinetics of NPs. Several physiological parameters (e.g. liver weight fraction of body weight) were identified to have a high influence on selected key dose metrics, indicating the need for additional interspecies comparison and scaling studies and to conduct pharmacokinetic studies of NPs in species that are more closely related to humans in these parameters. This PBPK model provides useful insights into the size, time, and species dependence of NP pharmacokinetics.

Controllable synthesis of tetrapod gold nanocrystals with precisely tunable near-infrared plasmon resonance towards highly efficient surface enhanced Raman spectroscopy bioimaging

Tetrapod gold nanocrystals have been controllably synthesized with tunable near-infrared plasmon resonance.

In situ synthesis of multidentate PEGylated chitosan modified gold nanoparticles with good stability and biocompatibility

To realize desirable functions in the rather complex biological systems, a suitable surface coating is desirable for gold nanoparticles, which plays an important role in their colloidal stability and biocompatibility.

Systemic delivery of axitinib with nanohybrid liposomal nanoparticles inhibits hypoxic tumor growth

Axitinib (AXT) is a potent and selective orally administered inhibitor of the vascular endothelial growth factor receptors 1-3 that contribute to the pathogenesis of solid tumors. The goal of the present study was to enhance the antiangiogenic and antitumor effects of AXT under hypoxia. Here we developed spherical polypeptide-coated hybrid liposomal nanoparticles (P-LNP/AXT) with a narrow size distribution and high loading efficiency. The cytotoxic effects of P-LNP/AXT on cancer cells were lower than those of AXT, and the human cancer cell lines SCC7, BT-474, and SH-SY5YP efficiently incorporated P-LNP/AXT. However, these formulations were not significantly internalized by the mouse macrophage cell line RAW 264.7, suggesting that they could evade the reticuloendothelial system. Western blotting analysis showed a significant increase in the level of expression of hydroxy-HIF-1α when cells were treated with P-LNP/AXT. The growth of tumors in mice treated with P-LNP/AXT was significantly inhibited compared with controls. Further, elevated levels of caspase-3 and poly (ADP-ribose) polymerase and reduced levels of platelet/endothelial cell adhesion molecule 1 (PECAM1, CD31) and Ki-67 in tumor cells suggested that tumor cells underwent apoptosis and that angiogenesis was inhibited within the tumor. Thus, P-LNP/AXT shows promise for cancer chemotherapy by inhibiting tumor angiogenesis.

Surface tailoring of nanoparticles via mixed-charge monolayers and their biomedical applications

The recent convergence of nanomaterials and medicine has provided an expanding horizon for people to achieve encouraging advances in many biomedical applications such as cancer diagnosis and therapy. However, to realize desirable functions in the rather complex biological systems, a suitable surface coating is greatly in need for nanoparticles (NPs), regardless of the species. In this review, a recently developed surface modification strategy is highlighted--mixed-charge monolayers--with an emphasis on the nanointerfaces of inorganic NPs. Two typical mixed-charge gold NPs (AuNPs) prepared from surface modifications with different combinations of oppositely charged alkanethiols are shown as detailed examples to discuss how the mixed-charge monolayer can help NPs meet the criteria for in vitro and in vivo biomedical applications, including those critical issues like colloidal stability, nonfouling properties, and smart responses (pH-sensitivity) for tumor targeting.

Multidentate polyethylene glycol modified gold nanorods for in vivo near-infrared photothermal cancer therapy

Gold nanorods (AuNRs), because of their strong absorption of near-infrared (NIR) light, are very suitable for in vivo photothermal therapy of cancer. However, appropriate surface modification must be performed on AuNRs before their in vivo application because of the high toxicity of their original stabilizer cetyltrimethylammonium bromide. Multidentate ligands have attracted a lot of attention for modification of inorganic nanoparticles (NPs) because of their high ligand affinity and multifunctionality, while the therapeutic effect of multidentate ligands modified NPs in vivo remains unexplored. Here, we modified AuNRs with a polythiol PEG-based copolymer. The multidentate PEG coated AuNRs (AuNR-PTPEGm950) showed good stabilities in high saline condition and wide pH range. And they had much stronger resistance to ligand competition of dithiothreitol (DTT) than AuNRs coated by monothiol-anchored PEG. The AuNR-PTPEGm950 had very low cytotoxicity and showed high efficacy for the ablation of cancer cells in vitro. Moreover, the AuNR-PTPEGm950 showed good stability in serum, and they had a long circulation time in blood that led to a high accumulation in tumors after intravenous injection. In vivo photothermal therapy showed that tumors were completely cured without reoccurrence by one-time irradiation of NIR laser after a single injection of these multidentate PEG modified AuNRs.