Surface and size effects on cell interaction of gold nanoparticles with both phagocytic and nonphagocytic cells

Safety Considerations of Cancer Nanomedicine-A Key Step toward Translation

The rate of translational effort of nanomedicine requires strategic planning of nanosafety research in order to enable clinical trials and safe use of nanomedicine in patients. Herein, the experiences that have emerged based on the safety data of classic liposomal formulations in the space of oncology are discussed, along with a description of the new challenges that need to be addressed according to the rapid expansion of nanomedicine platform beyond liposomes. It is valuable to consider the combined use of predictive toxicological assessment supported by deliberate investigation on aspects such as absorption, distribution, metabolism, and excretion (ADME) and toxicokinetic profiles, the risk that may be introduced during nanomanufacture, unique nanomaterials properties, and nonobvious nanosafety endpoints, for example. These efforts will allow the generation of investigational new drug-enabling safety data that can be incorporated into a rational infrastructure for regulatory decision-making. Since the safety assessment relates to nanomaterials, the investigation should cover the important physicochemical properties of the material that may lead to hazards when the nanomedicine product is utilized in humans.

Iron(II) phthalocyanine Loaded and AS1411 Aptamer Targeting Nanoparticles: A Nanocomplex for Dual Modal Imaging and Photothermal Therapy of Breast Cancer

Purpose

A multi-functional nanoplatform with diagnostic imaging and targeted treatment functions has aroused much interest in the nanomedical research field and has been paid more attention in the field of tumor diagnosis and treatment. However, some existing nano-contrast agents have encountered difficulties in different aspects during clinical promotion, such as complicated preparation process and low specificity. Therefore, it is urgent to find a nanocomplex with good targeting effect, high biocompatibility and significant therapeutic effect for the integration of diagnosis and treatment and clinical transformation.

Materials and Methods

Nanoparticles (NPs) targeting breast cancer were synthesized by phacoemulsification which had liquid fluorocarbon perfluoropentane(PFP) in the core and were loaded with Iron(II) phthalocyanine (FePc) on the shell. The aptamer (APT) AS1411 was outside the shell used as a molecular probe. Basic characterization and targeting abilities of the NPs were tested, and their cytotoxicity and biological safety in vivo were evaluated through CCK-8 assay and blood bio-chemical analysis. The photoacoustic (PA) and ultrasound (US) imaging system were used to assess the effects of AS1411-PLGA@FePc@PFP (A-FP NPs) as dual modal contrast agent in vitro and in vivo. The effects of photothermal therapy (PTT) in vitro and in vivo were evaluated through MCF-7 cells and tumor-bearing nude mouse models.

Results

A-FP NPs, with good stability, great biocompatibility and low toxicity, were of 201.87 ± 1.60 nm in diameter, and have an active targeting effect on breast cancer cells and tissues. With the help of PA/US imaging, it was proved to be an excellent dual modal contrast agent for diagnosis and guidance of targeted therapy. Meanwhile, it can heat up under near-infrared (NIR) laser irradiation and has achieved obvious antitumor effect both in vitro and in vivo experiments.

Conclusion

As a kind of nanomedicine, A-FP NPs can be used in the integration of diagnosis and treatment. The treatment effects and biocompatibility in vivo may provide new thoughts in the clinical transformation of nanomedicine and early diagnosis and treatment of breast cancer.

Ayurvedic processing of α-HgS gives novel physicochemistry and distinct toxicokinetics in zebrafish

Rasasindura (RS) is an Ayurvedic medicine, which contains ∼99% α-HgS. It is used as a rejuvenating agent and commonly used to treat diseases such as syphilis, insomnia, high fever, and nervous disorders. Cinnabar ore (α-HgS) is a well-known mineral, which is readily available. Despite it, Ayurvedic practitioners adopted an involved and tedious procedure for the preparation of RS. In this study, three samples, one was Ayurvedic (RS), the second one was the commercial (HGS), and the third one was cinnabar ore (CN), were physiochemically examined. Zebrafish model was employed for toxicity study with an oral dose of 100 mg/kg/day for the three samples for 10 days. We found that RS conferred novel physicochemical properties, which were not seen in HGS and CN. Significantly, the average crystallite size of RS was lowest (26 nm) as compared to HGS (31 nm) and CN (34 nm), and the rate of increase of crystallite size with temperature was lowest in RS. RS did not show any significant behavioral toxicity in zebrafish, which was seen with the HGS-and CN-treated zebrafish. HGS-and CN-treated zebrafish showed a significantly high (∗∗∗p < 0.001) decrease (77 ± 7.6% and 51 ± 6.5%, respectively) of glutathione (GSH) levels in the brain, however, for RS-treated zebrafish, the change of GSH was insignificant (26 ± 2.5%, p > 0.05). Interestingly, HGS significantly altered the γ-aminobutyric acid (GABA) in brain tissue. Therefore, among all three samples, RS exhibited the lowest toxicity, which can be credited to the distinct toxicokinetics by these samples.

Correction to Multisite Inhibitors for Enteric Coronavirus: Antiviral Cationic Carbon Dots Based on Curcumin

[This corrects the article DOI: 10.1021/acsanm.8b00779.].

Enhancing the Cellular Uptake and Antibacterial Activity of Rifampicin through Encapsulation in Mesoporous Silica Nanoparticles

An urgent demand exists for the development of novel delivery systems that efficiently transport antibacterial agents across cellular membranes for the eradication of intracellular pathogens. In this study, the clinically relevant poorly water-soluble antibiotic, rifampicin, was confined within mesoporous silica nanoparticles (MSN) to investigate their ability to serve as an efficacious nanocarrier system against small colony variants of Staphylococcus aureus (SCV S. aureus) hosted within Caco-2 cells. The surface chemistry and particle size of MSN were varied through modifications during synthesis, where 40 nm particles with high silanol group densities promoted enhanced cellular uptake. Extensive biophysical analysis was performed, using quartz crystal microbalance with dissipation (QCM-D) and total internal reflection fluorescence (TIRF) microscopy, to elucidate the mechanism of MSN adsorption onto semi-native supported lipid bilayers (snSLB) and, thus, uncover potential cellular uptake mechanisms of MSN into Caco-2 cells. Such studies revealed that MSN with reduced silanol group densities were prone to greater particle aggregation on snSLB, which was expected to restrict endocytosis. MSN adsorption and uptake into Caco-2 cells correlated well with antibacterial efficacy against SCV S. aureus, with 40 nm hydrophilic particles triggering a ~2.5-log greater reduction in colony forming units, compared to the pure rifampicin. Thus, this study provides evidence for the potential to design silica nanocarrier systems with controlled surface chemistries that can be used to re-sensitise intracellular bacteria to antibiotics by delivering them to the site of infection.

Influence of Gold Nanoparticles with Different Surface Charges on Localization and Monocyte Behavior

The use of gold nanoparticles (AuNP) has been established in nanocarriers, diagnostics, and biosensors. Access to the targeted sites of these nanomaterials could directly involve the first line of defense, the innate immune system. Charges of nanomaterials play a critical role in a number of aspects such as stabilization, cellular uptake, modulation, and function of cells. Interactions and modulations of the charged nanomaterials against the innate immune system may occur even at very low concentration. To understand the effects of charges on monocyte behavior, in this study, the positively and negatively charged AuNP (AuNP+ve and AuNP-ve) of the similar size and shape on cytotoxicity, recognition, cellular behavior, and function were evaluated in vitro using U937 human monocyte cells as an innate immunity model. Both types of AuNP at various concentrations (0-5 nM) exhibited low toxicity. In addition, the cellular internalization of the AuNP+ve and AuNP-ve, as determined by TEM, occurred by different mechanisms, and the internalization had no effect on cellular destruction, as implied by the low levels of %LDH. Interestingly, the AuNP+ve recognition and internalization seemingly entered cells through receptor dependence and strongly affected cellular response to express both pro-inflammatory (IL-1β) and anti-inflammatory (TGF-β) cytokines, while the AuNP-ve stimulated TNF-α expression. Nevertheless, the AuNP-treated cells maintained normal function when exposed to planktonic bacteria. Thus, these results indicated that one part of the immune system interacted with different surface-charged AuNP, suggesting appropiate immunomodulation in biomedicine.

Physicochemical characterization of Suvarna Bhasma, its toxicity profiling in rat and behavioural assessment in zebrafish model

ETHNOPHARMACOLOGICAL RELEVANCE

Suvarna Bhasma is a gold-based Ayurved medicine that has a wide range of therapeutic indications like tuberculosis, diabetes mellitus, rheumatoid arthritis and nervous diseases. Suvarna Bhasma is also used in Suvarnaprashana, an Ayurved advocated therapy being practised to improve immunity in children.

AIM OF THE STUDY

To augment traditional understanding, here we present an evidence-based study on Suvarna Bhasma regarding its physicochemical properties, toxicity and efficacy.

MATERIALS AND METHODS

Suvarna Bhasma was characterised by physicochemical characterization techniques such as scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and atomic emission spectroscopy (ICP-AES). Toxicity of Suvarna Bhasma was studied in Holtzman rats with daily oral dose from 3 mg/kg (therapeutic dose, TD) up to 30 mg/kg (10 TD) body weight for 90 days. Behavioural study, such as motor and geotactic behaviour were examined in zebrafish model to find out any sign of neurotoxicity or behavioural changes due to Suvarna Bhasma administration.

RESULTS

Suvarna Bhasma has two types of gold particles, large ones (~60 μm) having irregular shapes, and nano-sized spherical particles (starting from ~10 nm), the latter coated with Fe, Si, O, P and Na. XRD study revealed that all the peaks of Suvarna Bhasma match well with pure gold (face centred cube) with crystallites size 45 ± 2.8 nm. In rat studies, some change in biochemical parameters such as urea, creatinine and alanine aminotransferase (ALT) was observed mainly at the higher therapeutic dose; however, those parameters were within the normal range. There were no significant macroscopic as well as microscopic treatment-related alteration observed, in any of the organs and tissues evaluated. In zebrafish behavioural study, the motor parameters of Suvarna Bhasma treated fish showed normal behaviour analogous to the vehicle control group. Interestingly, the geotactic behaviour showed anxiolytic effects of Suvarna Bhasma as evidenced by the time spent in the upper zone, and average swimming height. The anxiolytic effects persisted for more than 30 days after withdrawing the Suvarna Bhasma treatment.

CONCLUSIONS

Suvarna Bhasma contained spherical gold nanoparticles. It was nontoxic in rat model at the does tested. Suvarna Bhasma has anxiolytic effects in zebrafish behavioural model.

Development of TPGS/F127/F68 mixed polymeric micelles: Enhanced oral bioavailability and hepatoprotection of syringic acid against carbon tetrachloride-induced hepatotoxicity

Syringic acid (SA), a natural polyphenol found in fruits and vegetables, is claimed to show notable hepatoprotection. Nevertheless, low solubility and bioavailability hamper the application of SA. This study aimed to investigate the potential of TPGS/F127/F68 mixed polymeric micelles as a sustained and liver-targeting nanocarrier for SA. Herein, the prepared SA-loaded TPGS/F127/F68 mixed polymeric micelles (SA-TPGS-Ms) were spherically-shaped and homogeneously-distributed nanoparticles with high entrapment efficiency (94.67 ± 2.05%) and sustained release. Besides, in-vitro cell culture studies revealed that SA-TPGS-Ms substantially promoted cellular uptake with excellent biocompatibility. After oral administration, SA-TPGS-Ms demonstrated an increased bioavailability (2.3-fold) and delayed in-vivo elimination compared with the free SA. Furthermore, the alleviation of oxidative stress and amelioration of hepatic injury in CCl₄-induced hepatotoxicity mice further demonstrated the excellent hepatoprotection of SA-TPGS-Ms. Collectively, SA-TPGS-Ms could be a promising nanocarrier for the utilization of SA in functional foods, with enhanced bioavailability and hepatoprotection.

A. I. Colorectal cancer stem cells: a review of targeted drug delivery by gold nanoparticles

The proposed schematic mechanismviawhich 5-fluorouracil-loaded gold nanoparticles conjugated with CD133 antibody target colorectal cancer stem cells.

Spherical Nucleic Acids with Tailored and Active Protein Coronae

Spherical nucleic acids (SNAs) are nanomaterials typically consisting of a nanoparticle core and a functional, dense, and highly oriented oligonucleotide shell with unusual biological properties that make them appealing for many applications, including sequence-specific gene silencing, mRNA quantification, and immunostimulation. When placed in biological fluids, SNAs readily interact with serum proteins, leading to the formation of ill-defined protein coronae on the surface, which can influence the targeting capabilities of the conjugate. In this work, SNAs were designed and synthesized with functional proteins, such as antibodies and serum albumin, deliberately adsorbed onto their surfaces. These particles exhibit increased resistance to protease degradation compared with native SNAs but still remain functional, as they can engage in hybridization with complementary oligonucleotides. SNAs with adsorbed targeting antibodies exhibit improved cellular selectivity within mixed cell populations. Similarly, SNAs coated with the dysopsonizing protein serum albumin show reduced macrophage uptake, providing a strategy for tailoring selective SNA delivery. Importantly, the protein coronae remain stable on the SNAs in human serum, exhibiting a less than 45% loss of protein through exchange after 12 h at 37 °C. Taken together, these results show that protein-SNA complexes and the method used to prepare them provide a new avenue for enhancing SNA stability, targeting, and biodistribution.

Cancer immunotherapy with immunoadjuvants, nanoparticles, and checkpoint inhibitors: Recent progress and challenges in treatment and tracking response to immunotherapy

Chemotherapy, surgery, and radiation are accepted as the preferred treatment modalities against cancer, but in recent years the use of immunotherapeutic approaches has gained prominence as the fourth treatment modality in cancer patients. In this approach, a patient's innate and adaptive immune systems are activated to achieve clearance of occult cancerous cells. In this review, we discuss the preclinical and clinical immunotherapeutic (e.g., immunoadjuvants (in-situ vaccines, oncolytic viruses, CXC antagonists, device activated agents), organic and inorganic nanoparticles, and checkpoint blockade) that are under investigation for cancer therapy and diagnostics. Additionally, the innovations in imaging of immune cells for tracking therapeutic responses and limitations (e.g., toxicity, inefficient immunomodulation, etc.) are described. Existing data suggest that if immune therapy is optimized, it can be a real and potentially paradigm-shifting cancer treatment frontier.

Highly hydrophilic cationic gold nanorods stabilized by novel quaternary ammonium surfactant with negligible cytotoxicity

The photothermal cancer therapy using cationic gold nanorods (GNRs) stabilized by quaternary ammonium salts (QAS) have a great potential to enhance conventional cancer treatment as it promises the effective eradication of cancer cells including cells resistant to radio- and chemo-therapy and the stimulation of anti-tumor immune response. However, as the cytotoxicity of the conventional alkanethiol-QAS compounds limits their utility in medicine, here we developed GNRs modified by novel highly hydrophilic cationic surfactant composed of the quaternary ammonium group and ethylene glycol chain N,N,N-trimethyl-3,6,9,12,15-pentaoxaheptadecyl-17-sulfanyl-1-ammonium bromide (POSAB) showing insignificant cytotoxicity in the free state. Surface modification of GNRs by POSAB allowed to prepare nanoparticles with good stability in water, high cellular uptake and localization in lysosomes that are a promising alternative to alkanethiol-stabilized GNRs especially for biomedical applications.

Advances on assessing nanotoxicity in marine fish - the pros and cons of combining an ex vivo approach and histopathological analysis in gills

The need to overcome logistic and ethical limitations of in vivo nanotoxicity evaluation in marine organisms is essential, mostly when dealing with fish. It is well established that medium/solvent conditions affect dispersion and agglomeration of nanoparticles (NPs), which represents a constraint towards a solid and realistic toxicity appraisal. In this way the pros and cons of an ex vivo approach, using a simplified exposure medium (seawater) and addressing gills histopathology, were explored. The nanotoxic potential of environmentally realistic concentrations of titanium dioxide NPs (TiO₂ NPs) was also assessed, disclosing the morpho-functional effects on the gills and the possible uptake/elimination processes. Excised gills of the Senegalese sole (Solea senegalensis) were directly exposed in artificial seawater to 20 and 200 μg L^-1 TiO₂ NPs, for 2 h and 4 h. Semi-quantitative and quantitative histological analyses were applied. The normal morphology of the gill's epithelia was only slightly altered in the control, reflecting protective mechanisms against the artificiality of the experimental conditions, which, together with the absence of differences in the global histopathological index (I_h), corroborated that the gill's morpho-functional features were not compromised, thereby validating the proposed ex vivo approach. TiO₂ NPs induced moderate severity and dissemination of histopathological lesions. After 2 h, a series of compensatory mechanisms occurred in NP treatments, implying an efficient response of the innate defense system (increasing number of goblet cells) and effective osmoregulatory ability (chloride cells proliferation). After 4 h, gills revealed signs of recovery (normalization of the number of chloride and goblet cells; similar I_h), highlighting the tissue viability and effective elimination and/or neutralization of NPs. The uptake of the TiO₂ NPs seemed to be favored by the higher particle sizes. Overall, the proposed approach emerged as a high-throughput, reliable, accurate and ethically commendable methodology for nanotoxicity assessment in marine fish.

Biophysical restriction of growth area using a monodispersed gold sphere nanobarrier prolongs the mitotic phase in HeLa cells

Gold nanoparticles are widely exploited for biological and biotechnical applications owing to their stability, biocompatibility, and known effects on cellular behaviors. Many studies have focused on nanoparticles that are internalized into cells, but extracellular nanoparticles also can regulate cell behavior, a practice known as in-plane surface nanotopography. We demonstrated that nanobarriers composed of morphologically homogeneous gold nanospheres prolonged the mitotic (M) phase in the cervical cancer cell line HeLa without inducing apoptosis. The nanobarrier was formed by electrostatic deposition of nanospheres on a negatively charged, fibronectin-coated substrate. We tested the effects of differently sized nanospheres. Gold nanospheres 42 nm in diameter were found to be non-toxic, while 111 nm nanospheres induced the production of reactive oxygen species, resulting in apoptotic cell death and arrest of cytokinesis. When exposed to sufficient 83 nm gold nanospheres to fabricate a surface nanobarrier, the M phase was delayed but cells proceeded to cytokinesis and the G1 phase. Live-cell imaging showed that the M phase increased by 2.9 h, 2.4 times longer than in control cells. Biophysical analyses indicated that this could be attributed to the specific size of the nanobarrier that physically limited the growth area around the cell.

Microfluidics-Assisted Size Tuning and Biological Evaluation of PLGA Particles

Polymeric particles made up of biodegradable and biocompatible polymers such as poly(lactic-co-glycolic acid) (PLGA) are promising tools for several biomedical applications including drug delivery. Particular emphasis is placed on the size and surface functionality of these systems as they are regarded as the main protagonists in dictating the particle behavior in vitro and in vivo. Current methods of manufacturing polymeric drug carriers offer a wide range of achievable particle sizes, however, they are unlikely to accurately control the size while maintaining the same production method and particle uniformity, as well as final production yield. Microfluidics technology has emerged as an efficient tool to manufacture particles in a highly controllable manner. Here, we report on tuning the size of PLGA particles at diameters ranging from sub-micron to microns using a single microfluidics device, and demonstrate how particle size influences the release characteristics, cellular uptake and in vivo clearance of these particles. Highly controlled production of PLGA particles with ~100 nm, ~200 nm, and >1000 nm diameter is achieved through modification of flow and formulation parameters. Efficiency of particle uptake by dendritic cells and myeloid-derived suppressor cells isolated from mice is strongly correlated with particle size and is most efficient for ~100 nm particles. Particles systemically administered to mice mainly accumulate in liver and ~100 nm particles are cleared slower. Our study shows the direct relation between particle size varied through microfluidics and the pharmacokinetics behavior of particles, which provides a further step towards the establishment of a customizable production process to generate tailor-made nanomedicines.

Peptide-Functionalized Nanostructured Microarchitectures Enable Rapid Mechanotransductive Differentiation

Microenvironmental factors play critical roles in regulating stem cell fate, providing a rationale to engineer biomimetic microenvironments that facilitate rapid and effective stem cell differentiation. Three-dimensional (3D) hierarchical microarchitectures have been developed to enable rapid neural differentiation of multipotent human mesenchymal stromal cells (HMSCs) via mechanotransduction. However, low cell viability during long-term culture and poor cell recovery efficiency from the architectures were also observed. Such problems hinder further applications of the architectures in stem cell differentiation. Here, we present improved 3D nanostructured microarchitectures functionalized with cell-adhesion-promoting arginylglycylaspartic acid (RGD) peptides. These RGD-functionalized architectures significantly upregulated long-term cell viability and facilitated effective recovery of differentiated cells from the architectures while maintaining high differentiation efficiency. Efficient recovery of highly viable differentiated cells enabled the downstream analysis of morphology and protein expression to be performed. Remarkably, even after the removal of the mechanical stimulus provided by the 3D microarchitectures, the recovered HMSCs showed a neuron-like elongated morphology for 10 days and consistently expressed microtubule-associated protein 2, a mature neural marker. RGD-functionalized nanostructured microarchitectures hold great potential to guide effective differentiation of highly viable stem cells.

Fabrication Of Gold Nanoparticles In Absence Of Surfactant As In Vitro Carrier Of Plasmid DNA

PURPOSE

This work aimed to synthesize surfactant-free AuNPs for targeted delivery of plasmid DNA encoded p53 gene and to avoid conventional production method of Gold nanoparticles (AuNPs) which may adversely affect the final shape, diversity, and size due to accumulation of the formulated surfactant - gold complex to the surface.

METHODS

The AuNPs were fabricated using seeded-growth method with L-Cystine methyl ester hydrochloride as capping agent, then loaded with plasmid DNA encoded p53 gene. The resultant AuNPs and AuNPs-p53 complex were evaluated for physical characteristics and morphology. Confirmation of complex formation was performed using gel electrophoresis. Furthermore, the efficient delivery and cytotoxicity behavior of the encoded gene were examined on both healthy lung cells (WI38) and cancerous lung cells (A549).

RESULTS

L-cysteine methyl ester hydrochloride AuNPs showed acceptable physical characteristics (30 nm, +36.9 mv, and spherical morphology). P53 attachment to AuNPs was confirmed by gel electrophoresis. The RT-PCR proved the overexpression of p53 by the fabricated AuNPs-p53 complex. The high percentage of cell viability in normal lung cell line (WI 38) proved the safety of L-cysteine methyl ester functionalized AuNPs. Additionally, the apoptotic effect due to expression of p53 gene loaded on AuNPs was only prominent in lung cancer cell line (A549), revealing selectivity and targeting efficiency of anticancer AuNPs-p53 complex.

CONCLUSION

AuNPs can be considered as a potential delivery system for effective transfection of plasmid DNA which can be used for successful treatment of cancer.

Internalization and effects on cellular ultrastructure of nickel nanoparticles in rat kidneys

Purpose: Since nanoparticles (NPs) are beginning to be introduced in medicine and industry, it is mendatory to evaluate their biological side-effects, among other things. The present study aimed to investigate the pathways by which nickel nanoparticles (NiNPs) enter nephrons and to evaluate their localization and effects on cellular ultrastructure.

Methods: Rats were injected intraperitoneally with 20 nm NiNPs (20 mg/Kg/b.w./day) for 28 consecutive days. Transmission electron microscope technique was used to detect localization of NiNPs and their effects on cellular ultrastructure in rat kidneys. Additionally, measurements of certain biochemical parameters such as creatinine, urea, uric acid and phosphorus for investigating renal function following NiNPs treatment were taken.

Results: The presence of NiNPs in the nephrons in treated rats was confirmed by transmission electron microscopy. NiNPs entered the renal tubules cells via various pathways. The results indicated that NiNPs administration induced ultrastructural changes in the proximal cells of renal tubules and certain glomerular cells (podocytes and mesangial cells). Additionally, NiNPs were found to be localized in the mitochondria, which led to a significant decrease in their density and morphology. Furthermore, cell death was induced in the glomerular cells as found with a Terminal deoxynucleotidyl transferase dUTP Nick End Labeling (TUNEL) assay and through detection of p35 using immunohistochemical staining.

Conclusion: Herein, NiNPs were found to induce various cellular ultrastructural changes in the kidneys of rats. NiNPs used diverse pathways to internalize into the cytoplasm of the proximal convoluted tubules (PT) cells across the basement membrane, and also through the plasma membrane of two adjacent PT cells. NiNPs internalization, accumulation and their alterations of the cellular ultrastructure affected rat renal function.

Biosynthesis of β-d-glucan‑gold nanoparticles, cytotoxicity and oxidative stress in mouse splenocytes

This study reports biosynthesis of gold-nanoparticles (AuNPs) by using β-d-glucans isolated from the yeast Yarrowia lypolitica D1. β-d-glucans serve as reducing and stabilizing mediators that induce the formation of AuNPs on the outer surface of the own β-d-glucan. The systems were physicochemically characterized by ultraviolet visible (UV-Vis) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and dynamic light scattering (DLS) analyses. The results revealed the generation of AuNPs with quasi-spherical shape or large one dimension (1D) gold-nanostructures (AuNSs) depending on the HAuCl₄ concentration. A cytotoxic study was assessed in mouse splenocytes. Contrary to that expected, important cytotoxicity was found in all β-d-gluc+AuNPs systems by an oxidative stress increase. This study discusses the cytotoxic mechanism, suggesting that the resulting β-d-gluc+AuNPs systems may not be candidates for the formulation of immunostimulants or nanocarriers for biomedical applications.

Probing the biological obstacles of nanomedicine with gold nanoparticles

Despite massive growth in nanomedicine research to date, the field still lacks fundamental understanding of how certain physical and chemical features of a nanoparticle affect its ability to overcome biological obstacles in vivo and reach its intended target. To gain fundamental understanding of how physical and chemical parameters affect the biological outcomes of administered nanoparticles, model systems that can systematically manipulate a single parameter with minimal influence on others are needed. Gold nanoparticles are particularly good model systems in this case as one can synthetically control the physical dimensions and surface chemistry of the particles independently and with great precision. Additionally, the chemical and physical properties of gold allow particles to be detected and quantified in tissues and cells with high sensitivity. Through systematic biological studies using gold nanoparticles, insights toward rationally designed nanomedicine for in vivo imaging and therapy can be obtained. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Optimising gold nanorods for photoacoustic imaging in vitro

Gold nanorods (AuNRs) can be synthesised with different sizes but similar aspect ratios and therefore similar surface plasmon resonances (SPRs). Their strong optical absorbance governed by their SPRs facilitates their ability to be used as molecular-targeted contrast agents for photoacoustic (PA) imaging. The size of AuNRs has an effect on the PA conversion efficiency, melting threshold, and cytotoxicity, indicating that size can have a significant impact on overall biomedical efficacy. We investigated these factors for four different AuNRs (widths of 10, 25, 40 and 50 nm) all with SPRs of 815 ± 26 nm. A size-dependent linear relationship between fluence and PA amplitude was observed, along with particle melting. Reshaping was confirmed via transmission electron microscopy and spectrophotometry at a laser fluence of 11 ± 1.7 mJ cm^-2, 20 ± 2.2 mJ cm^-2, and 40 ± 2.6 mJ cm^-2. Cytotoxicity was tested on lung cancer cells (A549) via a colourimetric assay at a maximum concentration of 3 × 10¹⁰ NP ml^-1. Results demonstrate the 40 nm and 50 nm AuNRs produced the highest signal for equivalent particle numbers, but displayed the highest toxicity. Conversely, the 10 nm AuNRs were the most efficient photoacoustic converters, at equivalent total mass. This study demonstrates the importance of AuNR size and concentration on selection of AuNRs for their eventual clinical use.

Development of Novel EE/Alginate Polyelectrolyte Complex Nanoparticles for Lysozyme Delivery: Physicochemical Properties and In Vitro Safety

The number of biologic drugs has increased in the pharmaceutical industry due to their high therapeutic efficacy and selectivity. As such, safe and biocompatible delivery systems to improve their stability and efficacy are needed. Here, we developed novel cationic polymethacrylate-alginate (EE-alginate) pNPs for the biologic drug model lysozyme (Lys). The impact of variables such as total charge and charge ratios over nanoparticle physicochemical properties as well as their influence over in vitro safety (viability/proliferation and cell morphology) on HeLa cells was investigated. Our results showed that electrostatic interactions between the EE-alginate and lysozyme led to the formation of EE/alginate Lys pNPs with reproducible size, high stability due to their controllable zeta potential, a high association efficiency, and an in vitro sustained Lys release. Selected formulations remained stable for up to one month and Fourier transform-Infrared (FT-IR) showed that the functional groups of different polymers remain identifiable in combined systems, suggesting that Lys secondary structure is retained after pNP synthesis. EE-alginate Lys pNPs at low concentrations are biocompatible, while at high concentrations, they show cytotoxic for HeLa cells, and this effect was found to be dose-dependent. This study highlights the potential of the EE-alginate, a novel polyelectrolyte complex nanoparticle, as an effective and viable nanocarrier for future drug delivery applications.

Current status and future perspectives of gold nanoparticle vectors for siRNA delivery

Discovering the vast therapeutic potential of siRNA opened up new clinical research areas focussing on a number of diseases and applications; however significant problems with siRNA stability and delivery have hindered its clinical applicability. As a result, interest in the development of practical siRNA delivery systems has grown in recent years. Of the numerous siRNA delivery strategies currently on offer, gold nanoparticles (AuNPs) stand out thanks to their biocompatibility and capacity to protect siRNA against degradation; not to mention the versatility offered by their tuneable shape, size and optical properties. Herein this review provides a complete summary of the methodologies for functionalizing AuNPs with siRNA, paying singular attention to the AuNP shape, size and surface coating, since these key factors heavily influence cellular interaction, internalization and, ultimately, the efficacy of the hybrid particle. The most noteworthy hybridization strategies have been highlighted along with the most innovative and outstanding in vivo studies with a view to increasing clinical interest in the use of AuNPs as siRNA nanocarriers.

Proliferation of Cells with Severe Nuclear Deformation on a Micropillar Array

Cellular responses on a topographic surface are fundamental topics about interfaces and biology. Herein, a poly(lactide- co-glycolide) (PLGA) micropillar array was prepared and found to trigger significant self-deformation of cell nuclei. The time-dependent cell viability and thus cell proliferation was investigated. Despite significant nuclear deformation, all of the examined cell types (Hela, HepG2, MC3T3-E1, and NIH3T3) could survive and proliferate on the micropillar array yet exhibited different proliferation abilities. Compared to the corresponding groups on the smooth surface, the cell proliferation abilities on the micropillar array were decreased for Hela and MC3T3-E1 cells and did not change significantly for HepG2 and NIH3T3 cells. We also found that whether the proliferation ability changed was related to whether the nuclear sizes decreased in the micropillar array, and thus the size deformation of cell nuclei should, besides shape deformation, be taken into consideration in studies of cells on topological surfaces.

Targeting Mitochondrial Dysfunction and Oxidative Stress in Activated Microglia using Dendrimer-Based Therapeutics

Mitochondrial oxidative stress is associated with many neurodegenerative diseases, such as traumatic brain injury (TBI). Targeted delivery of antioxidants to mitochondria has failed to translate into clinical success due to their nonspecific cellular localization, poor transport properties across multiple biological barriers, and associated side effects. These challenges, coupled with the complex function of the mitochondria, create the need for innovative delivery strategies. Methods: Neutral hydroxyl-terminated polyamidoamine (PAMAM) dendrimers have shown significant potential as nanocarriers in multiple brain injury models. N-acetyl cysteine (NAC) is a clinically used antioxidant and anti-inflammatory agent which has shown significant potency when delivered in a targeted manner. Here we present a mitochondrial targeting hydroxyl PAMAM dendrimer-drug construct (TPP-D-NAC) with triphenyl-phosphonium (TPP) for mitochondrial targeting and NAC for targeted delivery to mitochondria in injured glia. Co-localization and mitochondrial content of mitochondria-targeted and unmodified dendrimer were assessed in microglia and macrophages in vitro via immunohistochemistry and fluorescence quantification. Therapeutic improvements of TPP-D-NAC over dendrimer-NAC conjugate (D-NAC) and free NAC were evaluated in vitro in microglia under oxidative stress challenge. In vivo neuroinflammation targeting was confirmed in a rabbit model of TBI. Results: TPP-conjugated dendrimer co-localized significantly more with mitochondria than unmodified dendrimer without altering overall levels of cellular internalization. This targeting capability translated to significant improvements in the attenuation of oxidative stress by TPP-D-NAC compared to D-NAC and free NAC. Upon systemic administration in a rabbit TBI model, TPP-conjugated dendrimer co-localized specifically with mitochondria in activated microglia and macrophages in the white matter of the ipsilateral/injured hemisphere, confirming its BBB penetration and glial targeting capabilities. Conclusion: D-NAC has shown promising efficacy in many animal models of neurodegeneration, and this work provides evidence that modification for mitochondrial targeting can further enhance its therapeutic efficacy, particularly in diseases where oxidative stress-induced glial cell death plays a significant role in disease progression.

Mechanosensitive Endocytosis of High-Stiffness, Submicron Microgels in Macrophage and Hepatocarcinoma Cell Lines

The mechanical properties of submicron particles offer a unique design space for advanced drug-delivery particle engineering. However, the recognition of this potential is limited by a poor consensus about both the specificity and sensitivity of mechanosensitive endocytosis over a broad particle stiffness range. In this report, our model series of polystyrene-co-poly(N-isopropylacrylamide) (pS-co-NIPAM) microgels have been prepared with a nominally constant monomer composition (50 mol % styrene and 50 mol % NIPAM) with varied bis-acrylamide cross-linking densities to introduce a tuned spectrum of particle mechanics without significant variation in particle size and surface charge. While previous mechanosensitive studies use particles with moduli ranging from 15 kPa to 20 MPa, the pS-co-NIPAM particles have Young's moduli (E) ranging from 300 to 700 MPa, which is drastically stiffer than these previous studies as well as pure pNIPAM. Despite this elevated stiffness, particle uptake in RAW264.7 murine macrophages displays a clear stiffness dependence, with a significant increase in particle uptake for our softest microgels after a 4 h incubation. Preferential uptake of the softest microgel, pS-co-NIPAM-1 (E = 310 kPa), was similarly observed with nonphagocytic HepG2 hepatoma cells; however, the uptake kinetics were distinct relative to that observed for RAW264.7 cells. Pharmacological inhibitors, used to probe for specific routes of particle internalization, identify actin- and microtubule-dependent pathways in RAW264.7 cells as sensitive particle mechanics. For our pS-co-NIPAM particles at nominally 300-400 nm in size, this microtubule-dependent pathway was interpreted as a phagocytic route. For our high-stiffness microgel series, this study provides evidence of cell-specific, mechanosensitive endocytosis in a distinctly new stiffness regime that will further broaden the functional landscape of mechanics as a design space for particle engineering.

Iridium Nanoparticles for Multichannel Luminescence Lifetime Imaging, Mapping Localization in Live Cancer Cells

The development of long-lived luminescent nanoparticles for lifetime imaging is of wide interest as luminescence lifetime is environmentally sensitive detection independent of probe concentration. We report novel iridium-coated gold nanoparticles as probes for multiphoton lifetime imaging with characteristic long luminescent lifetimes based on iridium luminescence in the range of hundreds of nanoseconds and a short signal on the scale of picoseconds based on gold allowing multichannel detection. The tailor-made IrC₆ complex forms stable, water-soluble gold nanoparticles (AuNPs) of 13, 25, and 100 nm, bearing 1400, 3200, and 22 000 IrC₆ complexes per AuNP, respectively. The sensitivity of the iridium signal on the environment of the cell is evidenced with an observed variation of lifetimes. Clusters of iridium nanoparticles show lifetimes from 450 to 590 ns while lifetimes of 660 and 740 ns are an average of different points in the cytoplasm and nucleus. Independent luminescence lifetime studies of the nanoparticles in different media and under aggregation conditions postulate that the unusual long lifetimes observed can be attributed to interaction with proteins rather than nanoparticle aggregation. Total internal reflection fluorescence microscopy (TIRF), confocal microscopy studies and 3D luminescence lifetime stacks confirm the presence of bright, nonaggregated nanoparticles inside the cell. Inductively coupled plasma mass spectrometry (ICPMS) analysis further supports the presence of the nanoparticles in cells. The iridium-coated nanoparticles provide new nanoprobes for lifetime detection with dual channel monitoring. The combination of the sensitivity of the iridium signal to the cell environment together with the nanoscaffold to guide delivery offer opportunities for iridium nanoparticles for targeting and tracking in in vivo models.

Formulation and in vitro evaluation of a siRNA delivery nanosystem decorated with gH625 peptide for triple negative breast cancer theranosis

The development of an efficient small interfering RNA (siRNA) delivery system has held scientists interest since the discovery of the RNA interference mechanism (RNAi). This strategy gives hope for the treatment of many severe diseases. Herein, we developed hybrid nanovectors able to deliver siRNA to triple negative breast cancer cells. The nanovectors are based on PEGylated superparamagnetic iron oxide nanoparticles (SPION) functionalized with gH625 peptide, chitosan and poly-l-arginine. Every component has a key role and specific function: SPION is the core scaffolding the nanovector; PEG participates in the colloidal stability and the immune stealthiness; gH625 peptide promotes the nanovector internalization into cancer cells; cationic polymers provide the siRNA protection and favor siRNA endosomal escape and delivery to cytosol. The formulation was optimized by varying the amount of each compound. The efficacy of the siRNA retention and protection were investigated in the presence of high concentration of serum. Optimized nanovectors show a high uptake by MDA-MB-231 cells. The resulting down regulation of GFP expression was 73 ± 3% with our nanovector compared to 59 ± 8% obtained with the siRNA-Oligofectamine™ complex in the same conditions.

Impact of Anti-Biofouling Surface Coatings on the Properties of Nanomaterials and Their Biomedical Applications

Understanding and subsequently controlling non-specific interactions between engineered nanomaterials and biological environment have become increasingly important for further developing and advancing nanotechnology for biomedical applications. Such non-specific interactions, also known as the biofouling effect, mainly associate with the adsorption of biomolecules (such as proteins, DNAs, RNAs, and peptides) onto the surface of nanomaterials and the adhesion or uptake of nanomaterials by various cells. By altering the surface properties of nanomaterials the biofouling effect can lead to in situ changes of physicochemical properties, pharmacokinetics, functions, and toxicity of nanomaterials. This review provides discussions on the current understanding of the biofouling effect, the factors that affect the non-specific interactions associated with biofouling, and the impact of the biofouling effect on the performances and functions of nanomaterials. An overview of the development and applications of various anti-biofouling coating materials to preserve and improve the properties and functions of engineered nanomaterials for intended biomedical applications is also provided.

Gold nanoparticles in injectable calcium phosphate cement enhance osteogenic differentiation of human dental pulp stem cells

In this study, a novel calcium phosphate cement containing gold nanoparticles (GNP-CPC) was developed. Its osteogenic induction ability on human dental pulp stem cells (hDPSCs) was investigated for the first time. The incorporation of GNPs improved hDPSCs behavior on CPC, including better cell adhesion (about 2-fold increase in cell spreading) and proliferation, and enhanced osteogenic differentiation (about 2-3-fold increase at 14 days). GNPs endow CPC with micro-nano-structure, thus improving surface properties for cell adhesion and subsequent behaviors. In addition, GNPs released from GNP-CPC were internalized by hDPSCs, as verified by transmission electron microscopy (TEM), thus enhancing cell functions. The culture media containing GNPs enhanced the cellular activities of hDPSCs. This result was consistent with and supported the osteogenic induction results of GNP-CPC. In conclusion, GNP-CPC significantly enhanced the osteogenic functions of hDPSCs. GNPs are promising to modify CPC with nanotopography and work as bioactive additives thus enhance bone regeneration.

Therapeutic potential of carbohydrates as regulators of macrophage activation

It is well established for a broad range of disease states, including cancer and Mycobacterium tuberculosis infection, that pathogenesis is bolstered by polarisation of macrophages towards an anti-inflammatory phenotype, known as M2. As these innate immune cells are relatively long-lived, their re-polarisation to pro-inflammatory, phagocytic and bactericidal "classically activated" M1 macrophages is an attractive therapeutic approach. On the other hand, there are scenarios where the resolving inflammation, wound healing and tissue remodelling properties of M2 macrophages are beneficial - for example the successful introduction of biomedical implants. Although there are numerous endogenous and exogenous factors that have an impact on the macrophage polarisation spectrum, this review will focus specifically on prominent macrophage-modulating carbohydrate motifs with a view towards highlighting structure-function relationships and therapeutic potential.

Inorganic nanoparticles as potential regulators of immune response in dendritic cells

AIM

The spontaneous adsorption of proteins on nanoparticles (NPs) in biological media is exploited to prepare complexes of NPs and proteins from cancer cells' lysates for application in cancer immunotherapy.

MATERIALS & METHODS

Gold (Au) and silica NPs were synthesized, incubated with cancer cells' lysates and characterized. Dendritic cells (DCs) were challenged with protein-coated NPs, their maturation, viability and morphology were evaluated and lymphocytes T proliferation was determined.

RESULTS

Silica and Au NPs bound different pools of biomolecules from lysates, and are therefore promising selective carriers for antigens. When incubated with immature DCs, NPs were efficiently endocytosed without cytotoxicity. Finally, protein-coated AuNPs promoted DC maturation and DC-mediated lymphocyte proliferation, at variance with lysate alone and protein-coated silica NPs, that did not promote DCs maturation.

CONCLUSION

These results demonstrate that the spontaneous formation of protein coronas on NPs represents a possible approach to fast, easy, cost-effective DCs stimulation.

In vitro cytotoxicity evaluation of nano-carbon particles with different sp2/sp3 ratios

Graphitization occurs during the long-term service of a diamond-like carbon (DLC) modified artificial joint. Then, DLC wear debris, which are carbon particles with different sp²/sp³ ratios and sizes ranging from the nano- to micro-meter scale produced. In this paper, to promote the application of DLC coating for artificial joint modification, the cytotoxicity of DLC debris (nano-carbon particles, NCs) with different sp²/sp³ ratios was studied. The microstructure and physical characteristics of NCs with different sp²/sp³ ratios were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS). Meanwhile, osteoblasts and macrophages were applied to characterize the cytotoxicity of the NCs. In vitro cytotoxicity assay results indicated that cells incubated with NCs of different sp²/sp³ ratios had greater osteogenic capacity, and these particles caused a weaker immune response in comparison with CoCrMo particles. Taken together, the results indicated that NCs with different sp²/sp³ ratios presented a good cytocompatibility than CoCrMo particles. But no significant differences were observed among NCs with different sp²/sp³ ratios. The better cytocompatibility of NCs is mainly attributable to their surface charge.

Understanding cellular internalization pathways of silicon nanowires

Background

Understanding how cells interact with nanomaterials is important for rational design of nanomaterials for nanomedicine and transforming them for clinical applications. Particularly, the mechanism for one-dimensional (1D) nanomaterials with high aspect ratios still remains unclear.

Results

In this work, we present amine-functionalized silicon nanowires (SiNW-NH₂) entering CHO-β cells via a physical membrane wrapping mechanism. By utilizing optical microscopy, transmission electron microscopy, and confocal fluorescence microscopy, we successfully visualized the key steps of internalization of SiNW-NH₂ into cells.

Conclusion

Our results provide insight into the interaction between 1D nanomaterials and confirm that these materials can be used for understanding membrane mechanics through physical stress exerted on the membrane.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-017-0250-0) contains supplementary material, which is available to authorized users.

Effect of Gold Nanoparticle Size and Coating on Labeling Monocytes for CT Tracking

With advances in cell therapies, interest in cell tracking techniques to monitor the migration, localization, and viability of these cells continues to grow. X-ray computed tomography (CT) is a cornerstone of medical imaging but has been limited in cell tracking applications due to its low sensitivity toward contrast media. In this study, we investigate the role of size and surface functionality of gold nanoparticles for monocyte uptake to optimize the labeling of these cells for tracking in CT. We synthesized gold nanoparticles (AuNP) that range from 15 to 150 nm in diameter and examined several capping ligands, generating 44 distinct AuNP formulations. In vitro cytotoxicity and uptake experiments were performed with the RAW 264.7 monocyte cell line. The majority of formulations at each size were found to be biocompatible, with only certain 150 nm PEG functionalized particles reducing viability at high concentrations. High uptake of AuNP was found using small capping ligands with distal carboxylic acids (11-MUA and 16-MHA). Similar uptake values were found with intermediate sizes (50 and 75 nm) of AuNP when coated with 2000 MW poly(ethylene-glycol) carboxylic acid ligands (PCOOH). Low uptake values were observed with 15, 25, 100, and 150 nm PCOOH AuNP, revealing interplay between size and surface functionality. Transmission electron microscopy (TEM) and CT performed on cells revealed similar patterns of high gold uptake for 50 nm PCOOH and 75 nm PCOOH AuNP. These results demonstrate that highly negatively charged carboxylic acid coatings for AuNP provide the greatest internalization of AuNP in monocytes, with a complex dependency on size.

Nonspecific Colloidal-Type Interaction Explains Size-Dependent Specific Binding of Membrane-Targeted Nanoparticles

Emerging biomedical applications such as molecular imaging and drug delivery often require directed binding of nanoparticles to cell-membrane receptors. The specific apparent affinity of such ligand-functionalized particles is size-dependent, an observation so far solely attributed to multivalent receptor-ligand interaction. We question the universality of this explanation by demonstrating that the binding kinetics also depends on weak, attractive colloidal-type interaction between nanoparticles and a lipid membrane. Applying label-free single-particle imaging, we correlate binding of nanoparticles targeted to a cell-mimetic lipid membrane with the distribution of nontargeted particles freely diffusing close to the membrane interface. This analysis shows that already a weak, k_BT-scale attraction present between 50 nm gold nanoparticles and the membrane renders these particles an order of magnitude higher avidity compared to 20 nm particles. A stronger emphasis on nonspecific particle-membrane interaction might thus be required to accurately predict nanoparticle targeting and other similar processes such as cellular uptake of exosomes and viruses.