Charge and agglomeration dependent in vitro uptake and cytotoxicity of zinc oxide nanoparticles

Innovative surfactant-free synthesis of core-shell SiO2/ZnO particles: rapid ultrasonication and photocatalytic inhibition

This study demonstrates the preparation of SiO2/ZnO core-shell nanoparticles with controllable shell size and their optical properties. A facile ultrasonication method was utilized to prepare the core-shell particles in the absence of surfactant materials. The synthesis duration was 75% shorter than that required for the common sol-gel method, which favours its potential applicability in the future for mass production. Tetraethyl orthosilicate (TEOS) was used as the silica source, while the core material was prepared using zinc acetate dihydrate. The outer shell size could easily be controlled by changing the molar ratio of silica from 0.25 to 1.00. The experimental results show that increasing the silica ratio was effective in suppressing the self-agglomeration of ZnO and, further, in obtaining agglomeration-free particles. The investigation of the photoluminescence (PL) properties of nanometre-sized ZnO revealed several emission peaks in the ultraviolet (UV) wavelength range, indicating variations in bandgap energy. This did not appear in the spectrum of micrometre-sized ZnO particles. The core-shell particles produced with higher amounts of silica showed higher UV-A and UV-B absorption. In addition, the presence of silica reduced the photocatalytic activity of ZnO by 65% and reduced the PL intensity. The obtained emission peaks, intensity changes, and spectral characteristics open new avenues for further research on tailoring the properties of SiO2/ZnO core-shell structures for specific technological advancements. These advancements hold promising applications in UV attenuation materials, LED technologies, lenses, and solar cells within the realm of optical devices.

Nanocomposite-based smart fertilizers: A boon to agricultural and environmental sustainability

Fertilizers are indispensable agri-inputs to accomplish the growing food demand. The injudicious use of conventional fertilizer products has resulted in several environmental and human health complications. To mitigate these problems, nanocomposite-based fertilizers are viable alternative options. Nanocomposites, a novel class of materials having improved mechanical strength, barrier properties, and mechanical and thermal stability, are suitable candidates to develop eco-friendly slow/controlled release fertilizer formulations. In this review, the use of different nanocomposite materials developed for nutrient management in agriculture has been summarized with a major focus on their synthesis and characterization techniques, and application aspects in plant nutrition, along with addressing constraints and future opportunities of this domain. Further detailed studies on nanocomposite-based fertilizers are required to evaluate the cost-effective synthesis methods, in-depth field efficacy, environmental fate, stability, etc. before commercialization in the field of agriculture. The present review is expected to help the policy makers and all the stakeholders in the large-scale commercialization and application of nanocomposite-based smart fertilizer products with greater societal acceptance and environmental sustainability in near future.

Probing the interaction of zinc oxide nanorods with human serum albumin: A spectroscopic approach

Bio-functionalized metal oxide nanoparticles (NPs) have been taken great importance in biomedical fields. The use of nanoparticles as delivery agents of therapeutic molecules led the researchers to emphasize the potential impact of these NPs on bio-macromolecules as protein-nanoparticle complexes, which also extended their importance as vehicles in targeted drug delivery systems due to increased ease of administration, firmness, reduced toxic side effects, and half-life of drugs. Since human serum albumin is the blood protein responsible for transporting materials in the blood system, the interaction of these particles with HSA is essential to be understood before considering the nanoparticles for any individual biomedical application. In the present study, we synthesized zinc-oxide nanorods (ZONRs) using a microwave-assisted synthesis technique, and characterized them by XRD, FTIR, Raman, SEM-EDX, UV-Vis spectroscopy, and photoluminescence (PL) spectroscopy methods. The interaction studies were carried out using fluorescence spectroscopy, and the change in secondary structure was analyzed using CD spectroscopy. The results of MTT cell viability assay demonstrated that the ZONRs has potential cytotoxic properties.

Structural characterization and antibacterial activity of silver nanoparticles synthesized using a low-molecular-weight Royal Jelly extract

In recent years silver nanoparticles (Ag NPs) gained increased and widespread applications in various fields of industry, technology, and medicine. This study describes the green synthesis of silver nanoparticles (Ag NPs) applying a low-molecular-weight fraction (LMF) of Royal Jelly, the nanoparticle characterization, and particularly their antibacterial activity. The optical properties of NPs, characterized by UV–Vis absorption spectroscopy, showed a peak at ~ 430 nm. The hydrodynamic radius and concentration were determined by complementary dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). The particle morphology was investigated using transmission electron microscopy (TEM), and the crystallinity of the silver was confirmed by X-ray diffraction (XRD). The antibacterial activities were evaluated utilizing Gram-negative and Gram-positive bacteria and colony counting assays. The growth inhibition curve method was applied to obtain information about the corresponding minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC) required. Obtained results showed that (i) the sizes of Ag NPs are increasing within the increase of silver ion precursor concentration, (ii) DLS, in agreement with NTA, showed that most particles have dimensions in the range of 50–100 nm; (iii) E. coli was more susceptible to all Ag NP samples compared to B. subtilis.

Antagonistic Skin Toxicity of Co-Exposure to Physical Sunscreen Ingredients Zinc Oxide and Titanium Dioxide Nanoparticles

Being the main components of physical sunscreens, zinc oxide nanoparticles (ZnO NPs) and titanium dioxide nanoparticles (TiO₂ NPs) are often used together in different brands of sunscreen products with different proportions. With the broad use of cosmetics containing these nanoparticles (NPs), concerns regarding their joint skin toxicity are becoming more and more prominent. In this study, the co-exposure of these two NPs in human-derived keratinocytes (HaCaT) and the in vitro reconstructed human epidermis (RHE) model EpiSkin was performed to verify their joint skin effect. The results showed that ZnO NPs significantly inhibited cell proliferation and caused deoxyribonucleic acid (DNA) damage in a dose-dependent manner to HaCaT cells, which could be rescued with co-exposure to TiO₂ NPs. Further mechanism studies revealed that TiO₂ NPs restricted the cellular uptake of both aggregated ZnO NPs and non-aggregated ZnO NPs and meanwhile decreased the dissociation of Zn²⁺ from ZnO NPs. The reduced intracellular Zn²⁺ ultimately made TiO₂ NPs perform an antagonistic effect on the cytotoxicity caused by ZnO NPs. Furthermore, these joint skin effects induced by NP mixtures were validated on the epidermal model EpiSkin. Taken together, the results of the current research contribute new insights for understanding the dermal toxicity produced by co-exposure of different NPs and provide a valuable reference for the development of formulas for the secure application of ZnO NPs and TiO₂ NPs in sunscreen products.

Overview on Recent Developments in the Design, Application, and Impacts of Nanofertilizers in Agriculture

Nutrient management is always a great concern for better crop production. The optimized use of nutrients plays a key role in sustainable crop production, which is a major global challenge as it depends mainly on synthetic fertilizers. A novel fertilizer approach is required that can boost agricultural system production while being more ecologically friendly than synthetic fertilizers. As nanotechnology has left no field untouched, including agriculture, by its scientific innovations. The use of nanofertilizers in agriculture is in the early stage of development, but they appear to have significant potential in different ways, such as increased nutrient-use efficiency, the slow release of nutrients to prevent nutrient loss, targeted delivery, improved abiotic stress tolerance, etc. This review summarizes the current knowledge on various developments in the design and formulation of nanoparticles used as nanofertilizers, their types, their mode of application, and their potential impacts on agricultural crops. The main emphasis is given on the potential benefits of nanofertilizers, and we highlight the current limitations and future challenges related to the wide-scale application before field applications. In particular, the unprecedent release of these nanomaterials into the environment may jeopardize human health and the ecosystem. As the green revolution has occurred, the production of food grains has increased at the cost of the disproportionate use of synthetic fertilizers and pesticides, which have severely damaged our ecosystem. We need to make sure that the use of these nanofertilizers reduces environmental damage, rather than increasing it. Therefore, future studies should also check the environmental risks associated with these nanofertilizers, if there are any; moreover, it should focus on green manufactured and biosynthesized nanofertilizers, as well as their safety, bioavailability, and toxicity issues, to safeguard their application for sustainable agriculture environments.

Effective treatment of resistant opportunistic fungi associated with immuno-compromised individuals using silver biosynthesized nanoparticles

Drug resistance in filamentous fungus to antifungal medicines is a huge problem in biomedical applications; so, an effective strategy for treating opportunistic fungal infections is needed. Mentha piperita is a very fascinating plant to treat a variety of ailments as home remedies. Eighteen strains of Aspergillus species were used for this study which are having a unique antifungal resistance profile in presence of silver nanoparticles (AgNPs). AgNPs were prepared, using an aqueous extract of M. Piperita and characterized it by various techniques. Structural properties of AgNPs were systematically studied using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FT-IR), and Raman measurement, which emanate the single-phase fcc structure of silver nanoparticles. The spherical nature and elemental analysis of as-synthesized AgNPs were confirmed using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy, respectively. The optical study has been analyzed using UV–Vis spectroscopy and band gap was calculated as 2.51 eV, using Tauc plot. To analyze and validate the good efficacy of the disc approach, antifungal activity of AgNPs nanoparticles in different concentrations against isolates was achieved in both disc and broth microdilution. The extracellular enzymatic activity of A. fumigatus was found to explore the precise impact of nanoparticles on fungal metabolism. The antifungal efficacy of AgNPs against all fungi was highly successful in disc method. The broth approach underlined the favorable results of the disc method. It provided more precise results in determining the minimum inhibition concentration (MIC), as well as the minimum effective concentration (MEC). A. fumigatus (AM6) enzymatic activity was boosted by AgNPs. Also, ß-galactosidase, ß-glucuronidase, and ß-glucosidase are necessary enzymes whose activity has been boosted. Consequently, M. piperita AgNPs can play a major and intriguing function against resistant Aspergillus species with a significant shift in the enzymatic activity profile of fungi due to this action.

Quantitative considerations about the size dependence of cellular entry and excretion of colloidal nanoparticles for different cell types

Most studies about the interaction of nanoparticles (NPs) with cells have focused on how the physicochemical properties of NPs will influence their uptake by cells. However, much less is known about their potential excretion from cells. However, to control and manipulate the number of NPs in a cell, both cellular uptake and excretion must be studied quantitatively. Monitoring the intracellular and extracellular amount of NPs over time (after residual noninternalized NPs have been removed) enables one to disentangle the influences of cell proliferation and exocytosis, the major pathways for the reduction of NPs per cell. Proliferation depends on the type of cells, while exocytosis depends in addition on properties of the NPs, such as their size. Examples are given herein on the role of these two different processes for different cells and NPs.

Toxicity of Nanoparticles in Biomedical Application: Nanotoxicology

Nanoparticles are of great importance in development and research because of their application in industries and biomedicine. The development of nanoparticles requires proper knowledge of their fabrication, interaction, release, distribution, target, compatibility, and functions. This review presents a comprehensive update on nanoparticles' toxic effects, the factors underlying their toxicity, and the mechanisms by which toxicity is induced. Recent studies have found that nanoparticles may cause serious health effects when exposed to the body through ingestion, inhalation, and skin contact without caution. The extent to which toxicity is induced depends on some properties, including the nature and size of the nanoparticle, the surface area, shape, aspect ratio, surface coating, crystallinity, dissolution, and agglomeration. In all, the general mechanisms by which it causes toxicity lie on its capability to initiate the formation of reactive species, cytotoxicity, genotoxicity, and neurotoxicity, among others.

Sono-synthesis approach improves anticancer activity of ZnO nanoparticles: reactive oxygen species depletion for killing human osteosarcoma cells

Aim: To investigate the effect of ultrasound during the synthesis of ZnO nanoparticles (NPs) on their anticancer activity. Materials & methods: ZnO NPs were synthesized in the presence and absence of ultrasonic irradiation. Biological tests were performed on human osteosarcoma cancer cells (Saos-2). Results: The sono-synthesized sample indicated higher cytotoxicity than the conventional one. (IC₅₀ = 16.48 ± 0.41 μg/ml for sonochemical ZnO; 26.96 ± 0.33 μg/ml for conventional ZnO). Both sonochemical and conventional samples acted like antioxidants and reduced intracellular reactive oxygen species level. This reduction was more significant in cells treated with the sono-synthesized sample. The sono-synthesized ZnO NPs showed more tumor selectivity than the conventional sample. Conclusion: Sono-synthesis of ZnO NPs by a bath sonicator could improve their anticancer activity.

Silver Nanoparticles: Mechanism of Action and Probable Bio-Application

This review is devoted to the medical application of silver nanoparticles produced as a result of "green" synthesis using various living organisms (bacteria, fungi, plants). The proposed mechanisms of AgNPs synthesis and the action mechanisms on target cells are highlighted.

Zinc oxide nanoparticles (ZnO NPs) combined with cisplatin and gemcitabine inhibits tumor activity of NSCLC cells

Non-small cell lung cancer (NSCLC) is one of the most common malignancies worldwide. The use of a combination of chemotherapy drugs and zinc oxide nanoparticles (ZnO-NPs), which have proven to induce tumor-selective cell death, reduce the drug resistance and reduce the side effects in vitro. In the present study, we developed ZnO-NPs loaded with both cisplatin (Cp) and gemcitabine (Gem) (ZnO-NPs(Cp/Gem)), then the morphologies and the size distribution of ZnO-NPs(Cp/Gem) particles were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Also, MTT, western blot and Annexin V-PI were used to assess the anti-tumor role of ZnO-NPs(Cp/Gem) in A549 cells. The viability for A549 cells showed a significant decrease in the ZnO NPs(Cp/Gem) group, respectively relative to Cp, Gem, the combination of Cp and Gem (Cp+Gem), and ZnO-NPs loaded with Cp (ZnO-NPs(Cp)) or Gem (ZnO-NPs(Gem)). Furthermore, ZnO-NPs(Cp/Gem) remarkably enhanced the apoptosis-promoting effect of Cp and Gem in A549 cells. The xenograft model showed that Zno-NPS (Cp/Gem) significantly enhanced the inhibition of Cp and Gem on tumor formation. The above results suggested that therapy of NSCLC with ZnO-NPs(Cp/Gem) could enhance the cytotoxic action of chemotherapeutic agents synergistically, indicating a promising potential for ZnO-NPs in antitumor applications.

808 nm-activable core@multishell upconverting nanoparticles with enhanced stability for efficient photodynamic therapy

BACKGROUND

The unique upconversion properties of rare-earth-doped nanoparticles offers exciting opportunities for biomedical applications, in which near-IR remote activation of biological processes is desired, including in vivo bioimaging, optogenetics, and light-based therapies. Tuning of upconversion in purposely designed core-shell nanoparticles gives access to biological windows in biological tissue. In recent years there have been several reports on NIR-excitable upconverting nanoparticles capable of working in biological mixtures and cellular settings. Unfortunately, most of these nanosystems are based on ytterbium's upconversion at 980 nm, concurrent with water's absorption within the first biological window. Thus, methods to produce robust upconverting nanoplatforms that can be efficiently excited with other than 980 nm NIR sources, such as 808 nm and 1064 nm, are required for biomedical applications.

RESULTS

Herein, we report a synthetic method to produce aqueous stable upconverting nanoparticles that can be activated with 808 nm excitation sources, thus avoiding unwanted heating processes due to water absorbance at 980 nm. Importantly, these nanoparticles, once transferred to an aqueous environment using an amphiphilic polymer, remain colloidally stable for long periods of time in relevant biological media, while keeping their photoluminescence properties. The selected polymer was covalently modified by click chemistry with two FDA-approved photosensitizers (Rose Bengal and Chlorin e6), which can be efficiently and simultaneously excited by the light emission of our upconverting nanoparticles. Thus, our polymer-functionalization strategy allows producing an 808 nm-activable photodynamic nanoplatform. These upconverting nanocomposites are preferentially stored in acidic lysosomal compartments, which does not negatively affect their performance as photodynamic agents. Upon 808 nm excitation, the production of reactive oxidative species (ROS) and their effect in mitochondrial integrity were demonstrated.

CONCLUSIONS

In summary, we have demonstrated the feasibility of using photosensitizer-polymer-modified upconverting nanoplatforms that can be activated by 808 nm light excitation sources for application in photodynamic therapy. Our nanoplatforms remain photoactive after internalization by living cells, allowing for 808 nm-activated ROS generation. The versatility of our polymer-stabilization strategy promises a straightforward access to other derivatizations (for instance, by integrating other photosensitizers or homing ligands), which could synergistically operate as multifunctional photodynamic platforms nanoreactors for in vivo applications.

Preparation and characterization of positively surface charged zinc oxide nanoparticles against bacterial pathogens

Solvothermal synthesis was used to investigate the formation of zinc oxide (ZnO) nanoparticles (NPs). A series of ZnO NPs was synthesized with different relative ratios of didodecyldimethylammonium bromide (DDAB) and zinc nitrate (ZN). The variation in the molarity influenced the crystallinity, size, and morphology of the obtained ZnO NPs. X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and zeta potential analysis were used to study the characteristic features of the ZnO NPs. The ZnO surface charge, size, and morphological structure were highly reliant on the concentrations of DDAB and ZN. With increasing relative ratio of DDAB to ZN, the particle size of ZnO NPs decreased and the surface charge increased to higher positive value. The ZnO NPs synthesized with cationic liquid DDAB presented enhanced performance in preventing the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains. The antibacterial activity of ZnO NPs have direct contact with the microbial cell wall resulting in destruction of bacterial cell integrity, release of antimicrobial Zn²⁺ ions, and induce cell death. This is due to the positively charged smaller ZnO NPs, prepared with DDAB cationic surfactant, effectively acting as an antimicrobial agent against food-borne pathogenic bacteria.

Aggregation and dissolution of engineering nano Ag and ZnO pretreated with natural organic matters in the simulated lung biological fluids

The increasing application of engineered nanoparticles such as silver nanoparticles (nAg) and zinc oxide nanoparticles (nZnO), results in their accumulation in environmental media. The environmental natural organic matter (NOM) adsorbed by these nanoparticles may have great effects on the aggregation and dissolution of metall ions, which are interesting and important for the assessment of the inhalation risks of these airborne suspended NOM-coated nanoparticles to humans. Therefore, the aggregation and dissolution of nAg and nZnO pretreated with citric acid (CA), tartaric acid (TA) and fulvic acid (FA) in simulated lung biological fluids (artificial lysosomal fluid (ALF) and Gamble Solution) were investigated. The surface properties, morphology and size of the NOM-treated ENPs changed, but the crystalline phase was relatively stable when observed using surface-enhanced Raman scattering, transmission electron microscope, and X-ray diffraction. NOM treatment had no significant influence on the particle size of NOM-treated nAg and nZnO except for a decrease in the size of CA-treated nAg, and it could not promote the aggregation of NOM-treated nAg and nZnO except for the aggregation of TA-treated nAg in Gamble Solution or TA-treated nZnO in ALF. CA- and FA-treatments promoted the release of Zn²⁺ and Ag⁺, respectively, while no promotion was observed after TA-treatment. Therefore, NOM affects the release of Zn²⁺ and Ag⁺ from NOM-treated nAg and nZnO but does not promote the aggregation of NOM-treated nAg and nZnO, which influences the inhalation risk-based assessment.

Size-dependent cytotoxicity study of ZnO nanoparticles in HepG2 cells

Zinc oxide (ZnO) nanoparticles (NPs) are widely used in daily life. However, common utilization of ZnO NPs results in increases in environmental release, and their health hazards have attracted extensive attention. To investigate the cytotoxicity of ZnO NPs and their mechanism in HepG2 cells, a comprehensive analytical system was developed. The internalization, cytotoxic mechanism, death mechanism and elimination behavior of three sizes of ZnO NPs were studied by electrothermal vaporization (ETV)-inductively coupled plasma mass spectrometry (ICP-MS), MTT assays, GSH measurements, ROS measurements and analyses of apoptosis and gene expression. The size-, dose- and time-dependent characteristics of ZnO NPs were determined, and the metabolism of ZnO NPs in cells was discussed. The cytotoxicity of ZnO NPs was confirmed to depend on both the size and concentration and was attributed to the release of Zn²⁺, induction of oxidative stress and inflammatory response; the death mode of HepG2 cells incubated with ZnO NPs was necrotic rather than programmed cell death.

Characteristics of quantum dots phagocytosis by neutrophil granulocytes

This article describes the main morphological and biochemical features of neutrophil granulocytes in the process of phagocytosis of two types of quantum dots (CdSe/ZnS-MPA and CdSe/CdSeZnS/ZnS-PTVP). This study is the first to observe the transfer of large aggregates of quantum dots through neutrophils. During this process the cells demonstrate high chemotactic activity. Furthermore, neutrophil pseudopodia underwent alterations during the early stages of phagocytosis. The findings demonstrated that the biochemical profile of neutrophils is practically identical after phagocytosis of both types of quantum dots, but differs significantly from neutrophil metabolism after bacterial phagocytosis.

Comparative dissolution, uptake, and toxicity of zinc oxide particles in individual aquatic species and mixed populations

Potential differences in species susceptibility to nanoparticle (NP) contaminants make the use of multispecies community toxicity testing strategies beneficial in understanding NP risk to aquatic environments. Because of the limited knowledge of zinc oxide (ZnO) NP fate and toxicity, we conducted multispecies exposures and compared the responses of individual species to the same species in a community comprised of algae (Chlamydomonas reinhardtii), bacteria (Escherichia coli), crustaceans (Daphnia magna), and zebrafish (Danio rerio). Different-sized ZnO particles and ionic Zn were compared to investigate the contribution of particulate and dissolved Zn to aquatic organism toxicity. Each organism and community was exposed to Zn sources at 0.08, 0.8, and 8 mg Zn/L. The present results indicate that all 3 types of Zn elicited differential toxicity among test organisms, with stronger adverse outcomes observed in single species than within a community. The community assay (nanocosm) we developed increased resilience to all Zn exposures by 5 to 10% compared to individual exposures at equivalent concentrations. In addition, the uptake and toxicity of ZnO particles to aquatic communities appear to be driven by rapid dissolution and the concomitant impacts of zinc ion toxicity, and the size of the ZnO particles had little impact on uptake or toxicity. The nanocosm assay could be a useful screening tool for rapidly assessing the potential impacts of nanomaterials to aquatic species. Environ Toxicol Chem 2019;38:591-602. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Antibacterial and Photocatalytic Properties of ZnO-9-Aminoacridine Hydrochloride Hydrate Drug Nanoconjugates

The development of nanomaterial-based hybrid systems for healthcare and energy-related materials has attracted significant attention nowadays. Here, we have designed a nanocomposite of ZnO nanoparticles (NPs) with anticancer therapeutic drug 9-aminoacridine hydrochloride hydrate (9AA-HCl) for antibacterial and photocatalytic activities. Spectroscopic studies reveal that the photoinduced electron transfer from photoexcited 9AA-HCl to the conduction band of ZnO NP causes the generation of the reactive oxygen species (ROS), which is responsible for antibacterial activity and photocatalytic properties. It is seen that the efficiency of photodegradation of dye molecules increases in ZnO-9AA-HCl nanoconjugated systems than pure ZnO nanoparticles because of efficient charge separation. In addition, the antibacterial efficacy of the nanoconjugate is investigated using a strain of Gram-negative bacteria where the cell-killing activities are observed 99.99 and 100% for 20 and 21 μL/mL nanoconjugate, respectively, and very little cell-killing activity is observed for free ZnO NPs and free drug. Moreover, it is also observed that the nanoconjugate generates sufficient intracellular ROS that can hydrolyze 2',7'-dichlorodihydrofluoresceindiacetate (DCFH-DA) to highly fluorescent 2',7'-dichlorofluorescein (DCF). The outcome of the study will provide valuable information for designing new-edge nanoconjugate materials for potential applications in photocatalytic and antibacterial activities.

Large-scale immuno-magnetic cell sorting of T cells based on a self-designed high-throughput system for potential clinical application

In this contribution, we designed four types of immuno-magnetic nanoparticles for separation of different T cells (CD3⁺, CD4⁺, CD8⁺ and CD14⁺ T cells), and we established a new large-scale immuno-magnetic cell sorting procedure to achieve an enrichment of particular T cells using our designed auto-IMACS device. This device could achieve recyclable large-scale cell sorting, for which the throughput of the system reached ∼4000 mL and the maximum cell capacity was 4 × 10¹⁰. The collected cells were analyzed by flow cytometry and visual cytology data, and the effective selection rates of CD3⁺, CD4⁺, CD8⁺ and CD14⁺ T cells were 79.3%, 74.1%, 57.1% and 67.9%, respectively. The sorted CD8⁺ T cells still retained good cytotoxic activity against specific cells. In addition, the sorted T cells can also be further incubated in vitro and proliferated, and even could be infused back into patients for immunotherapy in the near future.

Quantitative Particle-Cell Interaction: Some Basic Physicochemical Pitfalls

There are numerous reports about particle-cell interaction studies in the literature. Many of those are performed in two-dimensional cell cultures. While the interpretation of such studies seems trivial at first sight, in fact for quantitative analysis some basic physical and physicochemical bases need to be considered. This starts with the dispersion of the particles, for which gravity, Brownian motion, and interparticle interactions need to be considered. The respective strength of these interactions determines whether the particles will sediment, are dispersed, or are agglomerated. This in turn largely influences their interaction with cells. While in the case of well-dispersed particles only a fraction of them will come into contact with cells in a two-dimensional culture, (agglomeration-induced) sedimentation drives the particles toward the cell surface, resulting in enhanced uptake.

The role of intracellular trafficking of CdSe/ZnS QDs on their consequent toxicity profile

Background

Nanoparticle interactions with cellular membranes and the kinetics of their transport and localization are important determinants of their functionality and their biological consequences. Understanding these phenomena is fundamental for the translation of such NPs from in vitro to in vivo systems for bioimaging and medical applications. Two CdSe/ZnS quantum dots (QD) with differing surface functionality (NH₂ or COOH moieties) were used here for investigating the intracellular uptake and transport kinetics of these QDs.

Results

In water, the COOH- and NH₂-QDs were negatively and positively charged, respectively, while in serum-containing medium the NH₂-QDs were agglomerated, whereas the COOH-QDs remained dispersed. Though intracellular levels of NH₂- and COOH-QDs were very similar after 24 h exposure, COOH-QDs appeared to be continuously internalised and transported by endosomes and lysosomes, while NH₂-QDs mainly remained in the lysosomes. The results of (intra)cellular QD trafficking were correlated to their toxicity profiles investigating levels of reactive oxygen species (ROS), mitochondrial ROS, autophagy, changes to cellular morphology and alterations in genes involved in cellular stress, toxicity and cytoskeletal integrity. The continuous flux of COOH-QDs perhaps explains their higher toxicity compared to the NH₂-QDs, mainly resulting in mitochondrial ROS and cytoskeletal remodelling which are phenomena that occur early during cellular exposure.

Conclusions

Together, these data reveal that although cellular QD levels were similar after 24 h, differences in the nature and extent of their cellular trafficking resulted in differences in consequent gene alterations and toxicological effects.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-017-0279-0) contains supplementary material, which is available to authorized users.

Multifunctional Core@Shell Magnetic Nanoprobes for Enhancing Targeted Magnetic Resonance Imaging and Fluorescent Labeling in Vitro and in Vivo

Core@shell magnetic nanoparticles (core@shell MNPs) are attracting widespread attention due to their enhancement properties for potential applications in hyperthermia treatment, magnetic resonance imaging (MRI), diagnostics, and so forth. Herein, we developed a facile thermal decomposition method for controllable synthesis of a superparamagnetic, monodispersed core@shell structure (Co@Mn = CoFe₂O₄@MnFe₂O₄) with uniform size distribution (σ < 5%, d_c ≈ 15 nm). The CoFe₂O₄ core could enhance magnetic anisotropy, and the MnFe₂O₄ shell could improve the magnetization value. The Co@Mn MNPs were transferred into aqueous solution with an amphiphilic polymer (labeled 2% TAMRA) and functionalized with PEG_2k and target molecules (folic acid, FA) to fabricate multifunctional PMA_TAMRA-Co@Mn-PEG_2k-FA nanoprobes. The obtained PMA_TAMRA-Co@Mn-PEG_2k-FA nanoprobes exhibit good biocompatibility, high T₂ relaxation values, and long-term fluorescence stability (at least 6 months). Our results demonstrate that the synthesized PMA_TAMRA-Co@Mn-PEG_2k-FA nanoprobes can effectively enhance the targeted MRI and fluorescent labeling in vitro and in vivo. The research outcomes will contribute to the rational design of new nanoprobes and provide a promising pathway to promote core@shell nanoprobes for further clinical contrast MRI and photodynamic therapy in the near future.

Optimizing conditions for labeling of mesenchymal stromal cells (MSCs) with gold nanoparticles: a prerequisite for in vivo tracking of MSCs

Background

Mesenchymal stromal cells (MSCs) have an inherent migratory capacity towards tumor tissue in vivo. With the future objective to quantify the tumor homing efficacy of MSCs, as first step in this direction we investigated the use of inorganic nanoparticles (NPs), in particular ca. 4 nm-sized Au NPs, for MSC labeling. Time dependent uptake efficiencies of NPs at different exposure concentrations and times were determined via inductively coupled plasma mass spectrometry (ICP-MS).

Results

The labeling efficiency of the MSCs was determined in terms of the amount of exocytosed NPs versus the amount of initially endocytosed NPs, demonstrating that at high concentrations the internalized Au NPs were exocytosed over time, leading to continuous exhaustion. While exposure to NPs did not significantly impair cell viability or expression of surface markers, even at high dose levels, MSCs were significantly affected in their proliferation and migration potential. These results demonstrate that proliferation or migration assays are more suitable to evaluate whether labeling of MSCs with certain amounts of NPs exerts distress on cells. However, despite optimized conditions the labeling efficiency varied considerably in MSC lots from different donors, indicating cell specific loading capacities for NPs. Finally, we determined the detection limits of Au NP-labeled MSCs within murine tissue employing ICP-MS and demonstrate the distribution and homing of NP labeled MSCs in vivo.

Conclusion

Although large amounts of NPs improve contrast for imaging, duration and extend of labeling needs to be adjusted carefully to avoid functional deficits in MSCs. We established an optimized labeling strategy for human MSCs with Au NPs that preserves their migratory capacity in vivo.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-017-0258-5) contains supplementary material, which is available to authorized users.

Nanoparticles for radiooncology: Mission, vision, challenges

Cancer is one of the leading non-communicable diseases with highest mortality rates worldwide. About half of all cancer patients receive radiation treatment in the course of their disease. However, treatment outcome and curative potential of radiotherapy is often impeded by genetically and/or environmentally driven mechanisms of tumor radioresistance and normal tissue radiotoxicity. While nanomedicine-based tools for imaging, dosimetry and treatment are potential keys to the improvement of therapeutic efficacy and reducing side effects, radiotherapy is an established technique to eradicate the tumor cells. In order to progress the introduction of nanoparticles in radiooncology, due to the highly interdisciplinary nature, expertise in chemistry, radiobiology and translational research is needed. In this report recent insights and promising policies to design nanotechnology-based therapeutics for tumor radiosensitization will be discussed. An attempt is made to cover the entire field from preclinical development to clinical studies. Hence, this report illustrates (1) the radio- and tumor-biological rationales for combining nanostructures with radiotherapy, (2) tumor-site targeting strategies and mechanisms of cellular uptake, (3) biological response hypotheses for new nanomaterials of interest, and (4) challenges to translate the research findings into clinical trials.

Generation of protective immunity against Orientia tsutsugamushi infection by immunization with a zinc oxide nanoparticle combined with ScaA antigen

Background

Zinc oxide nanoparticle (ZNP) has been applied in various biomedical fields. Here, we investigated the usage of ZNP as an antigen carrier for vaccine development by combining a high affinity peptide to ZNP.

Results

A novel zinc oxide-binding peptide (ZBP), FPYPGGDA, with high affinity to ZNP (K_a = 2.26 × 10⁶ M⁻¹) was isolated from a random peptide library and fused with a bacterial antigen, ScaA of Orientia tsutsugamushi, the causative agent of scrub typhus. The ZNP/ZBP-ScaA complex was efficiently phagocytosed by a dendritic cell line, DC2.4, in vitro and significantly enhanced anti-ScaA antibody responses in vivo compared to control groups. In addition, immunization with the ZNP/ZBP-ScaA complex promoted the generation of IFN-γ-secreting T cells in an antigen-dependent manner. Finally, we observed that ZNP/ZBP-ScaA immunization provided protective immunity against lethal challenge of O. tsutsugamushi, indicating that ZNP can be used as a potent adjuvant when complexed with ZBP-conjugated antigen.

Conclusions

ZNPs possess good adjuvant potential as a vaccine carrier when combined with an antigen having a high affinity to ZNP. When complexed with ZBP-ScaA antigen, ZNPs could induce strong antibody responses as well as protective immunity against lethal challenges of O. tsutsugamushi. Therefore, application of ZNPs combined with a specific soluble antigen could be a promising strategy as a novel vaccine carrier system.

Cytotoxicity, oxidative stress and inflammation induced by ZnO nanoparticles in endothelial cells: interaction with palmitate or lipopolysaccharide

Recent studies showed that ZnO nanoparticles (NPs) might induce the toxicity to human endothelial cells. However, little is known about the interaction between ZnO NPs and circulatory components, which is likely to occur when NPs enter the blood. In this study, we evaluated ZnO NP-induced cytotoxicity, oxidative stress and inflammation in human umbilical vein endothelial cells (HUVECs), with the emphasis on the interaction with palmitate (PA) or lipopolysaccharide (LPS), because PA and LPS are normal components in human blood that increase in metabolic diseases. Overall, ZnO NPs induced cytotoxicity and intracellular reactive oxygen species (ROS) at a concentration of 32 μg ml^-1 , but did not significantly affect the release of inflammatory cytokines or adhesion of THP-1 monocytes to HUVECs. In addition, exposure to ZnO NPs dose-dependently promoted intracellular Zn ions in HUVECs. PA and LPS have different effects. Two hundred μm PA significantly induced cytotoxicity and THP-1 monocyte adhesion, but did not affect ROS or release of inflammatory cytokines. In contrast, 1 μg ml^-1 LPS significantly induced ROS, release of inflammatory cytokines and THP-1 monocyte adhesion, but not cytotoxicity. The presence of ZnO NPs did not significantly affect the toxicity induced by PA or LPS. In addition, the accumulation of Zn ions after ZnO NP exposure was not significantly affected by the presence of PA or LPS. We concluded that there was no interaction between ZnO NPs and PA or LPS on toxicity to HUVECs in vitro. Copyright © 2016 John Wiley & Sons, Ltd.

Zwitterionic surface coating of quantum dots reduces protein adsorption and cellular uptake

We have studied the effect of the zwitterionic surface coating of quantum dots (QDs) on their interaction with a serum supplemented cell medium and their internalization by human cervical carcinoma (HeLa) cells. Zwitterionic QDs showed negligible adsorption of human serum albumin (HSA) selected as a model serum protein, in contrast to similar but negatively charged QDs. The incorporation of zwitterionic QDs by HeLa cells was found to be lower than for negatively charged QDs and for positively charged QDs, for which the uptake yield was largest. Our results suggest that the suppression of protein adsorption, here accomplished by zwitterionic QD surfaces, offers a strategy that allows for reducing the cellular uptake of nanoparticles.