Silver and Gold Nanoparticles Exposure to In Vitro Cultured Retina – Studies on Nanoparticle Internalization,Apoptosis, Oxidative Stress,Glial- and Microglial Activity

The complex network of neuronal cells in the retina makes it a potential target of neuronal toxicity – a risk factor for visual loss. With growing use of nanoparticles (NPs) in commercial and medical applications, including ophthalmology, there is a need for reliable models for early prediction of NP toxicity in the eye and retina. Metal NPs, such as gold and silver, gain much of attention in the ophthalmology community due to their potential to cross the barriers of the eye. Here, NP uptake and signs of toxicity were investigated after exposure to 20 and 80 nm Ag- and AuNPs, using an in vitro tissue culture model of the mouse retina. The model offers long-term preservation of retinal cell types, numbers and morphology and is a controlled system for delivery of NPs, using serum-free defined culture medium. AgNO₃-treatment was used as control for toxicity caused by silver ions. These end-points were studied; gross morphological organization, glial activity, microglial activity, level of apoptosis and oxidative stress, which are all well described as signs of insult to neural tissue. TEM analysis demonstrated cellular- and nuclear uptake of all NP types in all neuronal layers of the retina. Htx-eosin staining showed morphological disruption of the normal complex layered retinal structure, vacuole formation and pyknotic cells after exposure to all Ag- and AuNPs. Significantly higher numbers of apoptotic cells as well as an increased number of oxidative stressed cells demonstrated NP-related neuronal toxicity. NPs also caused increased glial staining and microglial cell activation, typical hallmarks of neural tissue insult. This study demonstrates that low concentrations of 20 and 80 nm sized Ag- and AuNPs have adverse effects on the retina, using an organotypic retina culture model. Our results motivate careful assessment of candidate NP, metallic or-non-metallic, to be used in neural systems for therapeutic approaches.     

Advances and potential application of gold nanoparticles in nanomedicine

Nanomedicine is an emerging research area which has brought new possibilities and promising applications in image, diagnosis, and treatment. Nanoparticles (NPs) for medicinal purposes can be made of several material types such as silica, carbon, different polymers, and metals as silver, copper, titanium, and gold. Gold NPs (AuNPs) are the most studied and used, mostly due to their characteristics including simple preparation, controllable size and distribution, biocompatibility, good acceptance of surface modifications, and specific surface plasmon resonance (SPR). This study reviews the scientific literature regarding the potential applications of AuNPs in the development of new diagnostic and therapeutic strategies for nanomedicine, including their biomedical use as a drug carrier, as an agent in radio and phototherapy, and bioimaging for image diagnosis. While it becomes clear that much research remains to be done to improve the use of these nanoparticles, with particular concern for safety issues, the evidence from the literature already points to the great potential of AuNPs in nanomedicine.     

Synthesis and in vivo evaluation of the biodistribution of a 18F-labeled conjugate gold-nanoparticle-peptide with potential biomedical application

Gold nanoparticles (AuNPs) have been extensively used in biological applications because of their biocompatibility, size, and ease of characterization, as well as an extensive knowledge of their surface chemistry. These features make AuNPs readily exploitable for biomedical applications, including drug delivery and novel diagnostic and therapeutic approaches. In a previous work, we studied ex vivo distribution of the conjugate C(AuNP)-LPFFD for its potential uses in the treatment of Alzheimer's disease. In this study, we covalently labeled the conjugate with [(18)F]-fluorobenzoate to study the in vivo distribution of the AuNP by positron emission tomography (PET). After intravenous administration in rat, the highest concentration of the radiolabeled conjugate was found in the bladder and urine with a lower proportion in the intestine, demonstrating progressive accumulation compatible with biliary excretion of the conjugate. The conjugate also accumulated in the liver and spleen. PET imaging allowed us to study the in vivo biodistribution of the AuNPs in a noninvasive and sensitive way using a reduced number of animals. Our results show that AuNPs can be covalently and radioactively labeled for PET biodistribution studies.     

Effect of the surface charge density of nanoparticles on their translocation across pulmonary surfactant monolayer: a molecular dynamics simulation

Interaction between nanoparticles (NPs) and pulmonary surfactant monolayer plays a very significant role in nanoparticle-based pulmonary drug delivery system. Previous researches have indicated that different properties of nanoparticles can affect their translocation across pulmonary surfactant monolayer. Here we performed coarse-grained molecular dynamics simulation aimed at nanoparticles’ surface charge density effect on their penetration behaviours. Several hydrophilic nanoparticles with different surface charge densities were modelled in the simulations. The results show that NPs’ surface charge density affects their translocation capability: the higher the surface charge densities of NPs are, the worse their translocation capability is. It will cause the structural changes of pulmonary surfactant monolayer, and inhibit the normal phase transition of the monolayer during the compression process. Besides, charged NPs can be adsorbed on the surface of the monolayer after translocation as a stable state, and the adsorption capability of NPs increases generally with the increase of surface charge densities. Our simulation results suggest that the study of nanoparticle-based pulmonary drug delivery system should consider the nanoparticles’ surface charge density effect in order to avoid biological toxicity and improve efficacy.     

Toxicity of gold nanoparticles (AuNPs): A review

Gold nanoparticles are a kind of nanomaterials that have received great interest in field of biomedicine due to their electrical, mechanical, thermal, chemical and optical properties. With these great potentials came the consequence of their interaction with biological tissues and molecules which presents the possibility of toxicity. This paper aims to consolidate and bring forward the studies performed that evaluate the toxicological aspect of AuNPs which were categorized into in vivo and in vitro studies. Both indicate to some extent oxidative damage to tissues and cell lines used in vivo and in vitro respectively with the liver, spleen and kidney most affected. The outcome of these review showed small controversy but however, the primary toxicity and its extent is collectively determined by the characteristics, preparations and physicochemical properties of the NPs. Some studies have shown that AuNPs are not toxic, though many other studies contradict this statement. In order to have a holistic inference, more studies are required that will focus on characterization of NPs and changes of physical properties before and after treatment with biological media. So also, they should incorporate controlled experiment which includes supernatant control Since most studies dwell on citrate or CTAB-capped AuNPs, there is the need to evaluate the toxicity and pharmacokinetics of functionalized AuNPs with their surface composition which in turn affects their toxicity. Functionalizing the NPs surface with more peculiar ligands would however help regulate and detoxify the uptake of these NPs.     

Plant protein-based hydrophobic fine and ultrafine carrier particles in drug delivery systems

For thousands of years, plants and their products have been used as the mainstay of medicinal therapy. In recent years, besides attempts to isolate the active ingredients of medicinal plants, other new applications of plant products, such as their use to prepare drug delivery vehicles, have been discovered. Nanobiotechnology is a branch of pharmacology that can provide new approaches for drug delivery by the preparation of biocompatible carrier nanoparticles (NPs). In this article, we review recent studies with four important plant proteins that have been used as carriers for targeted delivery of drugs and genes. Zein is a water-insoluble protein from maize; Gliadin is a 70% alcohol-soluble protein from wheat and corn; legumin is a casein-like protein from leguminous seeds such as peas; lectins are glycoproteins naturally occurring in many plants that recognize specific carbohydrate residues. NPs formed from these proteins show good biocompatibility, possess the ability to enhance solubility, and provide sustained release of drugs and reduce their toxicity and side effects. The effects of preparation methods on the size and loading capacity of these NPs are also described in this review.     

CeO2 nanoparticles synthesized through green chemistry are biocompatible: In vitro and in vivo assessment

Widespread use of cerium oxide (CeO₂) nanoparticles (NPs) is found in almost all areas of research due to their distinctive properties. CeO₂ NPs synthesized via green chemistry have been characterized for antioxidant, phytochemical, and biological potential. Physical characterization through scanning electron microscopy, XRD, and TGA showed that the NPs are circular in shape, 20‐25 nm in size, and stable in a wide range of temperature. NPs display significant antioxidant (32.7% free radical scavenging activity) and antileishmanial (IC₅₀ 48 µg mL^?1) properties. In vitro toxicity tested against lymphocytes verified that NPs are biocompatible (99.38% viability of lymphocytes at 2.5 μg mL^?1). In vivo toxicity experiments showed no harmful effects on rat serum chemistry and histology of various organs and did not even change the concentration of antioxidative enzymes, total protein contents, lipid peroxidation, and nitrosative stress. These observations are in line with the statement that plant‐based synthesis of CeO₂ NPs lessens or nullifies in vitro and in vivo toxicity and hence CeO₂ NPs are regarded as a safe and biocompatible material to be used in drug delivery.     

Synthesis of Peptide Mediated Au Core–Ag Shell Nanoparticles as Surface-Enhanced Raman Scattering Labels

As the fundamental understanding of metal–light interactions gains solid grounds, further research has been devoted to construct novel structures that take full advantage of such unique interactions, which is called plasmonics. In this report, the preparation of Au–Ag core–shell structures obtained by coating the Au surface with peptide and Raman reporter molecule and depositing an Ag layer on it is reported. The prepared Au–Ag NPs are tested for their surface-enhanced Raman scattering (SERS) performance. The negatively charged peptides with three different lengths, which are 3 (P1), 15 (P2), and 21 (P3) amino acid long, were chemically attached to 13 nm AuNPs along with Raman reporter molecule, carboxytetramethylrhodamine, and these modified AuNPs were coated with three different shell thickness of Ag metal. The prepared Au–Ag NPs were tested for their SERS performance and found that the Au–Ag NPs prepared with P2 and thickest shell performs best as SERS label.     

Characterization of intact antibody-drug conjugates from plasma/serum in vivo by affinity capture capillary liquid chromatography-mass spectrometry

Antibody–drug conjugates (ADCs) are designed to facilitate the targeted delivery of cytotoxic drugs to improve their tumor fighting effects and minimize systemic toxicity. However, efficacy and safety can potentially be compromised due to the release of conjugated drugs from the ADC with time while in circulation, resulting in changes in the drug-to-antibody ratio (DAR). Current understanding of this process is limited because existing methods such as immunoassays fail to distinguish ADCs with different DARs. Here we demonstrate a novel method with bead-based affinity capture and capillary liquid chromatography–mass spectrometry to allow direct measurement of drug release by quantifying DAR distributions of the ADC in plasma/serum. This method successfully identified individual intact conjugated antibody species produced due to drug loss from ADCs (e.g., an engineered site-specific anti-MUC16 THIOMAB–drug conjugate) and measured the corresponding DAR distributions in vitro and in vivo. Information obtained can provide insights into the mechanisms involved in drug loss and help to optimize ADC therapeutics. Other potential applications of the method may include characterization of posttranslational modifications, protein adducts, and immunogenicity.     

Poly(D,L-lactide-co-glycolide acid) nanoparticles for DNA delivery: waiving preparation complexity and increasing efficiency

When designing a nonviral gene delivery system based on polymeric nanoparticles (NPs), it is important to keep in mind obstacles associated with future clinical applications. Simplifying the procedure of NPs production and taking toxicity into account are the most important issues that need to be addressed. Toxicity concerns in clinical trials may be raised when using additives such as cationic polymers/lipids, buffering reagents, and proteins. Therefore, the aim of this study was to simplify the formulation of poly (lactide-co-glycolide) acid NPs by shortening steps such as sonication time and by avoiding the use of additives while preserving its efficiency. NPs (300 nm) were formulated using a modified w/o/w technique with DNA entrapment efficiency of 80%. Once achieving such NPs, formulation parameters such as DNA loading, release kinetics, DNA integrity and bioactivity, uptake by cells, and toxicity were addressed. The NPs were readily taken by several cell lines and were localized mostly in their endo-lysosomal compartments. The NPs did not affect cells viability. Most importantly, transfection studies in COS-7 and Cf2th cells resulted with a 250-fold protein expression levels when compared with the control. These expression levels are higher than ones achieved with more complicated NPs systems, demonstrating the efficiency of our simplified NPs for gene delivery.     

Nanoparticulate drug delivery systems for cancer chemotherapy

Nanoparticles (NPs) are, in general, colloidal particles, less than 1000 nm, that can be used for better drug delivery and prepared either by encapsulating the drug within a vesicle and or by dispersing the drug molecules within a matrix. Nanoparticulate drug delivery systems have been extensively studied in recent years for spatial and temporal delivery, especially in tumour and brain targeting. NPs have great promise for better drug delivery as found in both pharmaceutical and clinical research. As a drug carrier, NPs have significant advantages like better bioavailability, systemic stability, high drug loading, long blood circulation time and selective distribution in the organs/tissues with longer half life. The selective targeting of NPs can be achieved by the enhanced permeability and retention effect (EPR-effect), attaching specific ligands, or by making selective distribution due to change of the physiological conditions of specific systems like nature, pH, temperature, etc. It has been observed that drug-loaded NPs can have selective distribution to organs/tissues using different types of and proportions of polymers. The current aim of researchers is to prepare NPs that are long-lived with and that demonstrate the appropriate selective distribution for better therapy and thus improved clinical outcomes. Nanoparticulate drug delivery systems have the potential to deliver a drug to the target site with specificity and to maintain the desired concentration at the site for the intended time without untoward effects. In this review article, the methods for the preparation of NPs, their characterization, biodistribution, and pharmacokinetic characteristics are discussed.     

Targeting of nanoparticles to the clathrin-mediated endocytic pathway

Nanoparticles (NPs) are considered attractive carriers for gene therapy and drug delivery owing to their minor toxic effect and their ability to associate and internalize into mammalian cells. In this study, we compared the endocytosis into HeLa cells of NPs exposing either a negative or positive charge on their surface. The exposed charge significantly affected their ability to internalize as well as the cellular endocytosis mechanism utilized. Negatively charged NPs show an inferior rate of endocytosis and do not utilize the clathrin-mediated endocytosis pathway. On the other hand, positively charged NPs internalize rapidly via the clathrin-mediated pathway. When this pathway is blocked, NPs activate a compensatory endocytosis pathway that results in even higher accumulation of NPs. Overall, the addition of a positive charge to NPs may improve their potential as nanoparticulate carriers for drug delivery.     

Nanoparticulate drug delivery systems for cancer chemotherapy

Abstract

Nanoparticles (NPs) are, in general, colloidal particles, less than 1000 nm, that can be used for better drug delivery and prepared either by encapsulating the drug within a vesicle and or by dispersing the drug molecules within a matrix. Nanoparticulate drug delivery systems have been extensively studied in recent years for spatial and temporal delivery, especially in tumour and brain targeting. NPs have great promise for better drug delivery as found in both pharmaceutical and clinical research. As a drug carrier, NPs have significant advantages like better bioavailability, systemic stability, high drug loading, long blood circulation time and selective distribution in the organs/tissues with longer half life. The selective targeting of NPs can be achieved by the enhanced permeability and retention effect (EPR-effect), attaching specific ligands, or by making selective distribution due to change of the physiological conditions of specific systems like nature, pH, temperature, etc. It has been observed that drug-loaded NPs can have selective distribution to organs/tissues using different types of and proportions of polymers. The current aim of researchers is to prepare NPs that are long-lived with and that demonstrate the appropriate selective distribution for better therapy and thus improved clinical outcomes. Nanoparticulate drug delivery systems have the potential to deliver a drug to the target site with specificity and to maintain the desired concentration at the site for the intended time without untoward effects. In this review article, the methods for the preparation of NPs, their characterization, biodistribution, and pharmacokinetic characteristics are discussed.     

A model ternary heparin conjugate by direct covalent bond strategy applied to drug delivery system

A model ternary heparin conjugate by direct covalent bond strategy has been developed, in which modified heparin using active mix anhydride as intermediate conjugates with model drug molecule and model specific ligand, respectively. Designed ester bonds between model drug and heparin facilitate hydrolysis kinetics research. The strategy can be extended to design and synthesize a targeted drug delivery system. The key point is to use mixed anhydride groups as activating intermediates to mediate the synthesis of the ternary heparin conjugate. Formation of mixed anhydride is detected by the conductimetry experiment. The ternary heparin conjugate is characterized by ¹³C NMR, FT-IR and GPC, respectively. The decreased trend on degree of substitution (DS) is consistent with that of introduced anticancer drug and specific ligand in drug delivery system. Moreover, their anticoagulant activity is evaluated by measuring activated partial thromboplastin time (APTT) and anti-factor Xa activity. The results show that model ternary heparin conjugate with reduced anticoagulant activity may avoid the risk of severe hemorrhagic complication during the administration and is potential to develop a safe and effective drug delivery system on anticancer research.     

Adjusting the Balance between Effective Loading and Vector Migration of Macrophage Vehicles to Deliver Nanoparticles

The nature of macrophage allows the possibility that this cell type could be used as drug delivery system to track therapeutic drug nanoparticles (NPs) in cancer. However, there is no existing research on the regulation between effective loading of NPs and targeted delivery of macrophages. Here, we investigated the important parameters of intracellular NP quantity and the vector migration rate. Macrophage loading capacity was obtained by comparing the uptake quantity of varisized NPs, and the delivery ability of loaded cells was determined by measuring vector migration rates. We observed a positive correlation between the size of NPs and directed macrophage migration. Our findings suggest that the molecular mechanism of migration vector rate regulation involved increased expression levels of colony-stimulating factor-1 (CSF-1) receptor and integrin induced by 100-nm and 500-nm particles. The ability of macrophages uptake to varisized NPs showed the opposite trend, with the increased vector rate of cell migration influenced by NPs. We are able to demonstrate the important balance between effective macrophage loading and targeted delivery. By adjusting the balance parameters, it will be possible to utilize NPs in macrophage-mediated disease diagnosis and therapy.     

Stimuli-responsive nanocarriers for intracellular delivery

The emergence of different nanoparticles (NPs) has made a significant revolution in the field of medicine. Different NPs in the form of metallic NPs, dendrimers, polymeric NPs, carbon quantum dots and liposomes have been functionalized and used as platforms for intracellular delivery of biomolecules, drugs, imaging agents and nucleic acids. These NPs are designed to improve the pharmacokinetic properties of the drug, improve their bioavailability and successfully surpass physiological or pathological obstacles in the biological system so that therapeutic efficacy is achieved. In this review I present some of the current approaches used in intracellular delivery systems, with a focus on various stimuli-responsive nanocarriers, including cell-penetrating peptides, to highlight their various biomedical applications.     

微生物介导的金纳米颗粒合成

金纳米颗粒凭借其独特的光学和电化学特性,广泛应用于信息存储、化学传感、医学成像、药物传输以及生物标记等领域。近年来,生物法合成金纳米颗粒因其环境友好、绿色低毒等特点引起研究者的广泛关注。研究表明,多种微生物包括细菌、放线菌、真菌和病毒等均具有合成金纳米颗粒的能力。本文综述了微生物介导合成金纳米颗粒的特性、机制及应用,并对未来发展趋势进行了展望。     

Design of acid-activated cell penetrating peptide for delivery of active molecules into cancer cells

TP10-5 (TK) was screened as the most promising candidate among the designed analogues of transportan 10 (TP10), a cell penetrating peptide (CPP) with remarkable capacity for membrane translocation. However, low levels of specificity and high toxicity limit its successful use for drug delivery applications. Here, we developed a new type of acid-activated CPP (TH) by replacement of all lysines of TK with histidines. As expected, histidine-containing TH can be activated and subsequently enter cells at pH 6.0, whereas it is less active at pH 7.4. In contrast, the uptake of TK has no significant difference for both pH values. Importantly, the toxicity of TH is significantly lower than that of TK under physiological conditions. After attachment of camptothecin (CPT) to TH, this conjugate exhibited remarkable cytotoxicity to cancer cells in a pH-dependent manner compared with free CPT and TK-CPT. This study opens a new avenue to design CPPs that preferentially enter cells in acidic solid tumors, with minimal cellular uptake in normal tissues.     

Mechanisms of enhanced antiglioma efficacy of polysorbate 80‐modified paclitaxel‐loaded PLGA nanoparticles by focused ultrasound

The presence of blood‐brain barrier (BBB) greatly limits the availability of drugs and their efficacy against glioma. Focused ultrasound (FUS) can induce transient and local BBB opening for enhanced drug delivery. Here, we developed polysorbate 80‐modified paclitaxel‐loaded PLGA nanoparticles (PS‐80‐PTX‐NPs, PPNP) and examined the enhanced local delivery into the brain for glioma treatment by combining with FUS. Our result showed PPNP had good stability, fast drug release rate and significant toxicity to glioma cells. Combined with FUS, PPNP showed a stronger BBB permeation efficiency both in the in vitro and in vivo BBB models. Mechanism studies revealed the disrupted tight junction, reduced P‐glycoprotein expression and ApoE‐dependent PS‐80 permeation collectively contribute to the enhanced drug delivery, resulting in significantly stronger antitumour efficacy and longer survival time in the tumour‐bearing mice. Our study provided a new strategy to efficiently and locally deliver drugs into the brain to treat glioma.     

Gold nanoparticles and bioconjugation: a pathway for proteomic applications

In the last few years gold nanoparticles (AuNPs) became extremely interesting materials due to their enhanced optical, chemical and electrical properties. With the intention of taking advantage of those properties, the use of AuNPs has spread into a wide variety of areas such as physics, chemistry, biology, industry and medicine. More interestingly, their ability to form robust conjugates with biomolecules has given proteomics a new tool to improve aspects where the current methods to study proteins and their interactions in living cells cannot achieve the success required. In this review we present some of the current methods for AuNPs synthesis, the tailoring of their surface with ligands to improve stability and strategies to conjugate with biomolecules. Lastly, we also discuss their application in proteomic methods and recent developments in clinical diagnosis.