An Integrated Multilevel Analysis Profiling Biosafety and Toxicity Induced by Indium- and Cadmium-Based Quantum Dots in Vivo

In vivo safety evaluation method for nanomaterials for cancer therapy

Nanomaterials are extensively used in the diagnosis and treatment of cancer and other diseases because of their distinctive physicochemical properties, including the small size and ease of modification. The approval of numerous nanomaterials for clinical treatment has led to a significant increase in human exposure to these materials. When nanomaterials enter organisms, they interact with DNA, cells, tissues, and organs, potentially causing various adverse effects, such as genotoxicity, reproductive toxicity, immunotoxicity, and damage to tissues and organs. Therefore, it is crucial to elucidate the side effects and toxicity mechanisms of nanomaterials thoroughly before their clinical applications. Although methods for in vitro safety evaluation of nanomaterials are well established, systematic methods for in vivo safety evaluation are still lacking. This review focuses on the in vivo safety evaluation of nanomaterials and explores their potential effects. In addition, the experimental methods for assessing such effects in various disciplines, including toxicology, pharmacology, physiopathology, immunology, and bioinformatics are also discussed.

Highly Sensitive, Stable InP Quantum Dot Fluorescent Probes for Quantitative Immunoassay Through Nanostructure Tailoring and Biotin-Streptavidin Coupling

Nontoxic, highly sensitive InP quantum dot (QD) fluorescent immunoassay probes are promising biomedical detection modalities due to their unique properties. However, InP-based QDs are prone to surface oxidation, and the stability of InP QD-based probes in biocompatible environments remains a crucial challenge. Although the thick shell can provide some protection during the phase transfer process of hydrophobic QDs, the photoluminescence quantum yield (PLQY) is generally decreased because of the contradiction between lattice stress relaxation and thick shell growth. Herein, we developed thick-shell InP-based core/shell QDs by inserting a ZnSeS alloy layer. The ternary ZnSeS intermediate shell could effectively facilitate lattice stress relaxation and passivate the defect states. The synthesized InP/ZnSe/ZnSeS/ZnS core/alloy shell/shell QDs (CAS-InP QDs) with nanostructure tailoring revealed a larger size, high PLQY (90%), and high optical stability. After amphiphilic polymer encapsulation, the aqueous CAS-InP QDs presented almost constant fluorescence attenuation and stable PL intensity under different temperatures, UV radiation, and pH solutions. The CAS-InP QDs were excellent labels of the fluorescence-linked immunosorbent assay (FLISA) for detecting C-reactive protein (CRP). The biotin-streptavidin (Bio-SA) system was first introduced in the FLISA to further improve the sensitivity, and the CAS-InP QDs-based SA-Bio sandwich FLISA realized the detection of CRP with an impressive limit of detection (LOD) of 0.83 ng/mL. It is believed that the stable and sensitive InP QD fluorescent probes will drive the rapid development of future eco-friendly, cost-effective, and sensitive in vitro diagnostic kits.

Impact of Surface Ligand on the Biocompatibility of InP/ZnS Quantum Dots with Platelets

InP/ZnS quantum dots (QDs) have received a large focus in recent years as a safer alternative to heavy metal-based QDs. Given their intrinsic fluorescent imaging capabilities, these QDs can be potentially relevant for in vivo platelet imaging. The InP/ZnS QDs are synthesized and their biocompatibility investigated through the use of different phase transfer agents. Analysis of platelet function indicates that platelet-QD interaction can occur at all concentrations and for all QD permutations tested. However, as the QD concentration increases, platelet aggregation is induced by QDs alone independent of natural platelet agonists. This study helps to define a range of concentrations and coatings (thioglycolic acid and penicillamine) that are biocompatible with platelet function. With this information, the platelet-QD interaction can be identified using multiple methods. Fluorescent lifetime imaging microscopy (FLIM) and confocal studies have shown QDs localize on the surface of the platelet toward the center while showing evidence of energy transfer within the QD population. It is believed that these findings are an important stepping point for the development of fluorescent probes for platelet imaging.

Recent Advances in Chemistry, Mechanism, and Applications of Quantum Dots in Photodynamic and Photothermal Therapy

Semiconductor quantum dots (QD) are a kind of nanoparticle with unique optical properties that have attracted a lot of attention in recent years. In this paper, the characteristics of these nanoparticles and their applications in nanophototherapy have been reviewed. Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has gained special importance because of its high accuracy and local treatment due to the activation of the drug at the tumor site. PDT is a new way of cancer treatment that is performed by activating light-sensitive compounds named photosensitizers (PS) by light. PSs cause the destruction of diseased tissue through the production of singlet oxygen. PTT is another non-invasive method that induces cell death through the conversion of near-infrared light (NIR) into heat in the tumor situation by the photothermal agent (PA). Through using energy transfer via the FRET (Förster resonance energy transfer) process, QDs provide light absorption wavelength for both methods and cover the optical weaknesses of phototherapy agents.

Application of Se-Met to CdTe QDs significantly reduces toxicity by modulating redox balance and inhibiting apoptosis

Cadmium tellurium quantum dots (CdTe QDs) as one of the most widely used QDs have been reported the toxicity and biosafety in recent years, little work has been done to reduce their toxicity however. Based on the mechanisms of toxicity of CdTe QDs on liver target organs such as oxidative stress and apoptosis previously reported by other researchers, we investigated the mechanism of action of trace element selenium (Se) to mitigate the hepatotoxicity of CdTe QDs. The experimental results showed that Se-Met at 40-140 μg L-1 could enhance the function of intracellular antioxidant defense system and the molecular structure of related antioxidant enzymes by reduce the production of ROS by 45%, protecting the activity of antioxidants and up-regulating the expression of selenoproteins with antioxidant functions, Gpx1 increase 225% and Gpx4 upregulated 47%. In addition, Se-Met could alleviate CdTe QDs-induced apoptosis by regulating two apoptosis-inducing factors, as intracellular caspase 3/9 expression levels were reduced by 70% and 87%, decreased Ca2+ concentration, and increased mitochondrial membrane potential measurements. Overall, this study indicates that Se-Met has a significant protective effect on the hepatotoxicity of CdTe QDs. Se-Met can be applied to the preparation of CdTe QDs to inhibit its toxicity and break the application limitation.

In vivo neuromodulation of animal behavior with organic semiconducting oligomers

Modulating neural activity with electrical or chemical stimulus can be used for fundamental and applied research. Typically, neuronal stimulation is performed with intracellular and extracellular electrodes that deliver brief electrical pulses to neurons. However, alternative wireless methodologies based on functional materials may allow clinical translation of technologies to modulate neuronal function. Here, we show that the organic semiconducting oligomer 4-[2-{2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophen-3-yl}ethoxy]butane-1-sulfonate (ETE-S) induces precise behaviors in the small invertebrate Hydra, which were dissected through pharmacological and electrophysiological approaches. ETE-S-induced behavioral response relies on the presence of head neurons and calcium ions and is prevented by drugs targeting ionotropic channels and muscle contraction. Moreover, ETE-S affects Hydra's electrical activity enhancing the contraction burst frequency. The unexpected neuromodulatory function played by this conjugated oligomer on a simple nerve net opens intriguing research possibilities on fundamental chemical and physical phenomena behind organic bioelectronic interfaces for neuromodulation and on alternative methods that could catalyze a wide expansion of this rising technology for clinical applications.

An update on the biological effects of quantum dots: From environmental fate to risk assessment based on multiple biological models

Quantum dots (QDs) are zero-dimension nanomaterials with excellent physical and chemical properties, which have been widely used in environmental science and biomedicine. Therefore, QDs are potential to cause toxicity to the environment and enter organisms through migration and bioenrichment effects. This review aims to provide a comprehensive and systematic analysis on the adverse effects of QDs in different organisms based on recently available data. Following PRISMA guidelines, this study searched PubMed database according to the pre-set keywords, and included 206 studies according to the inclusion and elimination criteria. CiteSpace software was firstly used to analyze the keywords of included literatures, search for breaking points of former studies, and summarize the classification, characterization and dosage of QDs. The environment fate of QDs in the ecosystems were then analyzed, followed with comprehensively summarized toxicity outcomes at individual, system, cell, subcellular and molecular levels. After migration and degradation in the environment, aquatic plants, bacteria, fungi as well as invertebrates and vertebrates have been found to be suffered from toxic effects caused by QDs. Aside from systemic effects, toxicity of intrinsic QDs targeting to specific organs, including respiratory system, cardiovascular system, hepatorenal system, nervous system and immune system were confirmed in multiple animal models. Moreover, QDs could be taken up by cells and disturb the organelles, which resulted in cellular inflammation and cell death, including autophagy, apoptosis, necrosis, pyroptosis and ferroptosis. Recently, several innovative technologies, like organoids have been applied in the risk assessment of QDs to promote the surgical interventions of preventing QDs' toxicity. This review not only aimed at updating the research progress on the biological effects of QDs from environmental fate to risk assessment, but also overcame the limitations of available reviews on basic toxicity of nanomaterials by interdisciplinarity and provided new insights for better applications of QDs.

Green synthesis of glyco-CuInS2 QDs with visible/NIR dual emission for 3D multicellular tumor spheroid and in vivo imaging

Glyco-quantum dots (glyco-QDs) have attracted significant interest in bioimaging applications, notably in cancer imaging, because they effectively combine the glycocluster effect with the exceptional optical properties of QDs. The key challenge now lies in how to eliminate the high heavy metal toxicity originating from traditional toxic Cd-based QDs for in vivo bioimaging. Herein, we report an eco-friendly pathway to prepare nontoxic Cd-free glyco-QDs in water by the "direct" reaction of thiol-ending monosaccharides with metal salts precursors. The formation of glyco-CuInS₂ QDs could be explained by a nucleation-growth mechanism following the LaMer model. As-prepared four glyco-CuInS₂ QDs were water-soluble, monodispersed, spherical in shape and exhibited size range of 3.0-4.0 nm. They exhibited well-separated dual emission in the visible region (500-590 nm) and near-infrared range (~ 827 nm), which may be attributable to visible excitonic emission and near-infrared surface defect emission. Meanwhile, the cell imaging displayed the reversibly distinct dual-color (green and red) fluorescence in tumor cells (HeLa, A549, MKN-45) and excellent membrane-targeting properties of glyco-CuInS₂ QDs based on their good biorecognition ability. Importantly, these QDs succeed in penetrating uniformly into the interior (the necrotic zone) of 3D multicellular tumor spheroids (MCTS) due to their high negative charge (zeta potential values ranging from - 23.9 to - 30.1 mV), which overcame the problem of poor penetration depth of existing QDs in in vitro spheroid models. So, confocal analysis confirmed their excellent ability to penetrate and label tumors. Thus, the successful application in in vivo bioimaging of these glyco-QDs verified that this design strategy is an effective, low cost and simple procedure for developing green nanoparticles as cheap and promising fluorescent bioprobes.

Potential Development of N-Doped Carbon Dots and Metal-Oxide Carbon Dot Composites for Chemical and Biosensing

Among carbon-based nanomaterials, carbon dots (CDs) have received a surge of interest in recent years due to their attractive features such as tunable photoluminescence, cost effectiveness, nontoxic renewable resources, quick and direct reactions, chemical and superior water solubility, good cell-membrane permeability, and simple operation. CDs and their composites have a large potential for sensing contaminants present in physical systems such as water resources as well as biological systems. Tuning the properties of CDs is a very important subject. This review discusses in detail heteroatom doping (N-doped CDs, N-CDs) and the formation of metal-based CD nanocomposites using a combination of matrices, such as metals and metal oxides. The properties of N-CDs and metal-based CDs nanocomposites, their syntheses, and applications in both chemical sensing and biosensing are reviewed.

Quantum Dots and Their Interaction with Biological Systems

Quantum dots are nanocrystals with bright and tunable fluorescence. Due to their unique property, quantum dots are sought after for their potential in several applications in biomedical sciences as well as industrial use. However, concerns regarding QDs’ toxicity toward the environment and other biological systems have been rising rapidly in the past decade. In this mini-review, we summarize the most up-to-date details regarding quantum dots’ impacts, as well as QDs’ interaction with mammalian organisms, fungal organisms, and plants at the cellular, tissue, and organismal level. We also provide details about QDs’ cellular uptake and trafficking, and QDs’ general interactions with biological structures. In this mini-review, we aim to provide a better understanding of our current standing in the research of quantum dots, point out some knowledge gaps in the field, and provide hints for potential future research.

Reproductive toxicity of InP/ZnS QDs in male rare minnow (Gobiocypris rarus)

InP/ZnS quantum dots (QDs) stand out among cadmium-free alternatives for higher exciton Bohr radius and strong quantum confined effect. In this study, the reproductive toxicity and mechanism of InP/ZnS QDs at different concentrations in male Chinese rare minnows (Gobiocypris rarus) were investigated. The results showed that QDs in 800 nmol/L concentration group could enter the testes after 1 d of exposure and caused changes in the structure of the testes, including the scattered distribution of seminal vesicles, reduction in germ cells and vacuolation in some areas of interstitial cells. The expression levels of androgen receptor (Ar) and doublesex and mab-3 related transcription factor 1 (Dmrt1) and the tight junction protein-related genes β-catenin and occludin were upregulated in rare minnows. The sperm quality and ATP content of parents in the 800 nmol/L treatment group were significantly decreased. Continuous detection of the development of F1 generation embryos showed that parental exposure to InP/ZnS QDs reduced the heart rate and spontaneous movement frequency of F1 generation embryos, and the fertilization rate of the F1 generation in the 800 nmol/L treatment group was significantly reduced. In general, the sperm quality and testicular structure of adult rare minnows were not significantly affected by concentrations below 400 nmol/L. High-concentration InP/ZnS QDs exposure can damage the integrity of the blood-testis barrier (BTB) and cause reproductive damage to the parents of rare minnows, which will continue to the next generation and affect their development.

The Aquatic Invertebrate Hydra vulgaris Releases Molecular Messages Through Extracellular Vesicles

Recent body of evidence demonstrates that extracellular vesicles (EVs) represent the first language of cell-cell communication emerged during evolution. In aquatic environments, transferring signals between cells by EVs offers protection against degradation, allowing delivering of chemical information in high local concentrations to the target cells. The packaging of multiple signals, including those of hydrophobic nature, ensures target cells to receive the same EV-conveyed messages, and the coordination of a variety of physiological processes across cells of a single organisms, or at the population level, i.e., mediating the population’s response to changing environmental conditions. Here, we purified EVs from the medium of the freshwater invertebrate Hydra vulgaris, and the molecular profiling by proteomic and transcriptomic analyses revealed multiple markers of the exosome EV subtype, from structural proteins to stress induced messages promoting cell survival. Moreover, positive and negative regulators of the Wnt/β-catenin signaling pathway, the major developmental pathway acting in body axial patterning, were identified. Functional analysis on amputated polyps revealed EV ability to modulate both head and foot regeneration, suggesting bioactivity of the EV cargo and opening new perspectives on the mechanisms of developmental signalling. Our results open the path to unravel EV biogenesis and function in all cnidarian species, tracing back the origin of the cell-cell, cross-species or cross-kingdom communication in aquatic ecosystems.

Multilabel hybridization probes for sequence-specific detection of sepsis-related drug resistance genes in plasmids

Emerging antimicrobial drug resistance is increasing the complexity involved in treating critical conditions such as bacterial induced sepsis. Methods for diagnosing specific drug resistance tend to be rapid or sensitive, but not both. Detection methods like sequence-specific single-molecule analysis could address this concern if they could be adapted to work on smaller targets similar to those produced in traditional clinical situations. In this work we demonstrate that a 120 bp double stranded polynucleotide with an overhanging single stranded 25 bp probe sequence can be created by immobilizing DNA with a biotin/streptavidin magnetic bead system, labeling with SYBR Gold, and rinsing the excess away while the probe retains multiple fluorophores. These probes with multiple fluorophores can then be used to label a bacterial plasmid target in a sequence-specific manner. These probes enabled the detection of 1 pM plasmid samples containing a portion of an antibiotic resistance gene sequence. This system shows the possibility of improving capture and fluorescence labeling of small nucleic acid fragments, generating lower limits of detection for clinically relevant samples while maintaining rapid processing times.

Seamless integration of bioelectronic interface in an animal model via in vivo polymerization of conjugated oligomers

Leveraging the biocatalytic machinery of living organisms for fabricating functional bioelectronic interfaces, in vivo, defines a new class of micro-biohybrids enabling the seamless integration of technology with living biological systems. Previously, we have demonstrated the in vivo polymerization of conjugated oligomers forming conductors within the structures of plants. Here, we expand this concept by reporting that Hydra, an invertebrate animal, polymerizes the conjugated oligomer ETE-S both within cells that expresses peroxidase activity and within the adhesive material that is secreted to promote underwater surface adhesion. The resulting conjugated polymer forms electronically conducting and electrochemically active μm-sized domains, which are inter-connected resulting in percolative conduction pathways extending beyond 100 μm, that are fully integrated within the Hydra tissue and the secreted mucus. Furthermore, the introduction and in vivo polymerization of ETE-S can be used as a biochemical marker to follow the dynamics of Hydra budding (reproduction) and regeneration. This work paves the way for well-defined self-organized electronics in animal tissue to modulate biological functions and in vivo biofabrication of hybrid functional materials and devices.

NIR-quantum dots in biomedical imaging and their future

Fluorescence imaging has gathered interest over the recent years for its real-time response and high sensitivity. Developing probes for this modality has proven to be a challenge. Quantum dots (QDs) are colloidal nanoparticles that possess unique optical and electronic properties due to quantum confinement effects, whose excellent optical properties make them ideal for fluorescence imaging of biological systems. By selectively controlling the synthetic methodologies it is possible to obtain QDs that emit in the first (650-950 nm) and second (1000-1400 nm) near infra-red (NIR) windows, allowing for superior imaging properties. Despite the excellent optical properties and biocompatibility shown by some NIR QDs, there are still some challenges to overcome to enable there use in clinical applications. In this review, we discuss the latest advances in the application of NIR QDs in preclinical settings, together with the synthetic approaches and material developments that make NIR QDs promising for future biomedical applications.

The cytotoxicity of core-shell or non-shell structure quantum dots and reflection on environmental friendly: A review

Quantum dots are widely applicated into bioindustry and research owing to its superior properties such as broad excitation spectra, narrow bandwidth emission spectra and high resistance to photo-bleaching. However, the toxicity of quantum dots should not be underestimated and aroused widespread concern. The surface properties and size of quantum dots are critical relevant properties on toxicity. Then, the core/shell structure becomes one common way to affect the activity of quantum dots such as enhance biocompatibility and stability. Except those toxicity it induced, the problem it brought into the environment such as the degradation of quantum dot similarly becomes a hot issue. This review initially took a brief scan of current research on the cytotoxicity of QDs and the mechanism behind that over the past five years. Mainly discussion concentrated on the diversity of structure on quantum dots whether played a key role on the cytotoxicty of quantum dots. It also discussed the role of different shells with metal or nonmetal cores and the influence on the environment.

Toxicity evaluation of cadmium-containing quantum dots: A review of optimizing physicochemical properties to diminish toxicity

Fluorescent quantum dots (QDs) have received extensive attention because of their excellent optical properties and wide utilization in biological and biomedical areas. Nonetheless, there have been intense concerns on the cytotoxicity assessment of cadmium-containing QDs due to free cadmium ions release and nano-size effects. This paper reviews the representative synthetic strategies for preparation of cadmium-containing QDs and their applications. Then the toxicity assessments of QDs from cell studies to animal models are discussed, which can aid in improving our understanding of the cytotoxicity of QDs, and the toxicity mechanism is proposed. Several critical physicochemical properties of QDs are discussed and suggestions are provided for optimizing QDs design in view of minimal cytotoxicity. Finally, accurate detection techniques and systematic methodologies for the toxicity assessment of QDs are expected to achieve further breakthroughs in the future, especially in-situ, real-time, and rapid quantitative analysis methods.

Nephrotoxicity Evaluation of Indium Phosphide Quantum Dots with Different Surface Modifications in BALB/c Mice

InP QDs have shown a great potential as cadmium-free QDs alternatives in biomedical applications. It is essential to understand the biological fate and toxicity of InP QDs. In this study, we investigated the in vivo renal toxicity of InP/ZnS QDs terminated with different functional groups—hydroxyl (hQDs), amino (aQDs) and carboxyl (cQDs). After a single intravenous injection into BALB/c mice, blood biochemistry, QDs distribution, histopathology, inflammatory response, oxidative stress and apoptosis genes were evaluated at different predetermined times. The results showed fluorescent signals from QDs could be detected in kidneys during the observation period. No obvious changes were observed in histopathological detection or biochemistry parameters. Inflammatory response and oxidative stress were found in the renal tissues of mice exposed to the three kinds of QDs. A significant increase of KIM-1 expression was observed in hQDs and aQDs groups, suggesting hQDs and aQDs could cause renal involvement. Apoptosis-related genes (Bax, Caspase 3, 7 and 9) were up-regulated in hQDs and aQDs groups. The above results suggested InP/ZnS QDs with different surface chemical properties would cause different biological behaviors and molecular actions in vivo. The surface chemical properties of QDs should be fully considered in the design of InP/ZnS QDs for biomedical applications.

Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media

Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%.

Revisiting the cytotoxicity of quantum dots: an in-depth overview

Recently, medical research has been shifting its focus to nanomedicine and nanotherapeutics in the pursuit of drug development research. Quantum dots (QDs) are a critical class of nanomaterials due to their unique properties, which include optical, electronic, and engineered biocompatibility in physiological environments. These properties have made QDs an attractive biomedical resource such that they have found application as both in vitro labeling and in vivo theranostic (therapy-diagnostic) agents. Considerable research has been conducted exploring the suitability of QDs in theranostic applications, but the cytotoxicity of QDs remains an obstacle. Several types of QDs have been investigated over the past decades, which may be suitable for use in biomedical applications if the barrier of cytotoxicity can be resolved. This review attempts to report and analyze the cytotoxicity of the major QDs along with relevant related aspects.

In Vivo Bioengineering of Fluorescent Conductive Protein-Dye Microfibers

Engineering protein-based biomaterials is extremely challenging in bioelectronics, medicine, and materials science, as mechanical, electrical, and optical properties need to be merged to biocompatibility and resistance to biodegradation. An effective strategy is the engineering of physiological processes in situ, by addition of new properties to endogenous components. Here we show that a green fluorescent semiconducting thiophene dye, DTTO, promotes, in vivo, the biogenesis of fluorescent conductive protein microfibers via metabolic pathways. By challenging the simple freshwater polyp Hydra vulgaris with DTTO, we demonstrate the stable incorporation of the dye into supramolecular protein-dye co-assembled microfibers without signs of toxicity. An integrated multilevel analysis including morphological, optical, spectroscopical, and electrical characterization shows electrical conductivity of biofibers, opening the door to new opportunities for augmenting electronic functionalities within living tissue, which may be exploited for the regulation of cell and animal physiology, or in pathological contexts to enhance bioelectrical signaling.

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The oligothiophene DTTO promotes the synthesis of microfibers in Hydra vulgaris

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DTTO co-assembles with proteins giving rise to fluorescent and conductive microfibers

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The biofiber synthesis is an active process, based on protein synthesis

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In situ produced hybrid microfibers have great potential in biolectronics and biomedicine

Gold Nanorods and Nanoprisms Mediate Different Photothermal Cell Death Mechanisms In Vitro and In Vivo

Photothermal therapy (PTT) is an efficient method of inducing localized hyperthermia and can be achieved using gold nanoparticles as photothermal agents. However, there are many hurdles to get over before this therapy can safely reach the clinics, including nanoparticles' optimal shape and the accurate prediction of cellular responses. Here, we describe the synthesis of gold nanorods and nanoprisms with similar surface plasmon resonances in the near-infrared (NIR) and comparable photothermal conversion efficiencies and characterize the response to NIR irradiation in two biological systems, melanoma cells and the small invertebrate Hydra vulgaris. By integrating animal, cellular, and molecular biology approaches, we show a diverse outcome of nanorods and nanoprisms on the two systems, sustained by the elicitation of different pathways, from necrosis to programmed cell death mechanisms (apoptosis and necroptosis). The comparative multilevel analysis shows great accuracy of in vivo invertebrate models to predict overall responses to photothermal challenging and superior photothermal performance of nanoprisms. Understanding the molecular pathways of these responses may help develop optimized nanoheaters that, safe by design, may improve PTT efficacy for clinical purposes.

In vivo Comparison of the Biodistribution and Toxicity of InP/ZnS Quantum Dots with Different Surface Modifications

INTRODUCTION

Indium phosphide (InP) quantum dots (QDs) have shown a broad application prospect in the fields of biophotonics and nanomedicine. However, the potential toxicity of InP QDs has not been systematically evaluated. In particular, the effects of different surface modifications on the biodistribution and toxicity of InP QDs are still unknown, which hinders their further developments. The present study aims to investigate the biodistribution and in vivo toxicity of InP/ZnS QDs.

METHODS

Three kinds of InP/ZnS QDs with different surface modifications, hQDs (QDs-OH), aQDs (QDs-NH2), and cQDs (QDs-COOH) were intravenously injected into BALB/c mice at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively. Biodistribution of three QDs was determined through cryosection fluorescence microscopy and ICP-MS analysis. The subsequent effects of InP/ZnS QDs on histopathology, hematology and blood biochemistry were evaluated at 1, 3, 7, 14 and 28 days post-injection.

RESULTS

These types of InP/ZnS QDs were rapidly distributed in the major organs of mice, mainly in the liver and spleen, and lasted for 28 days. No abnormal behavior, weight change or organ index were observed during the whole observation period, except that 2 mice died on Day 1 after 25 mg/kg BW hQDs treatment. The results of H&E staining showed that no obvious histopathological abnormalities were observed in the main organs (including heart, liver, spleen, lung, kidney, and brain) of all mice injected with different surface-functionalized QDs. Low concentration exposure of three QDs hardly caused obvious toxicity, while high concentration exposure of the three QDs could cause some changes in hematological parameters or biochemical parameters related to liver function or cardiac function. More attention needs to be paid on cQDs as high-dose exposure of cQDs induced death, acute inflammatory reaction and slight changes in liver function in mice.

CONCLUSION

The surface modification and exposure dose can influence the biological behavior and in vivo toxicity of QDs. The surface chemistry should be fully considered in the design of InP-based QDs for their biomedical applications.

In Vivo Biotransformations of Indium Phosphide Quantum Dots Revealed by X-Ray Microspectroscopy

Many attempts have been made to synthesize cadmium-free quantum dots (QDs), using nontoxic materials, while preserving their unique optical properties. Despite impressive advances, gaps in knowledge of their intracellular fate, persistence, and excretion from the targeted cell or organism still exist, precluding clinical applications. In this study, we used a simple model organism (Hydra vulgaris) presenting a tissue grade of organization to determine the biodistribution of indium phosphide (InP)-based QDs by X-ray fluorescence imaging. By complementing elemental imaging with In L-edge X-ray absorption near edge structure, unique information on in situ chemical speciation was obtained. Unexpectedly, spectral profiles indicated the appearance of In-O species within the first hour post-treatment, suggesting a fast degradation of the InP QD core in vivo, induced mainly by carboxylate groups. Moreover, no significant difference in the behavior of bare core QDs and QDs capped with an inorganic Zn(Se,S) gradient shell was observed. The results paralleled those achieved by treating animals with an equivalent dose of indium salts, confirming the preferred bonding type of In³⁺ ions in Hydra tissues. In conclusion, by focusing on the chemical identity of indium along a 48 h long journey of QDs in Hydra, we describe a fast degradation process, in the absence of evident toxicity. These data pave the way to new paradigms to be considered in the biocompatibility assessment of QD-based biomedical applications, with greater emphasis on the dynamics of in vivo biotransformations, and suggest strategies to drive the design of future applied materials for nanotechnology-based diagnosis and therapeutics.

Influence of the Core/Shell Structure of Indium Phosphide Based Quantum Dots on Their Photostability and Cytotoxicity

With the goal to improve their photostability, InP-based QDs are passivated with three types of inorganic shells, namely (i) a gradient ZnSe_xS_1−x shell, (ii) an additional ZnS shell on top of the gradient shell with two different thicknesses (core/shell/shell, CSS), (iii) an alumina coating on top of ZnS. All three systems have photoluminescence quantum yields (PLQY) > 50% and similar PL decay times (64–67 ns). To assess their photostability they are incorporated into a transparent poly (methyl methacrylate) (PMMA) matrix and exposed to continuous irradiation with simulated sunlight in a climate chamber. The alumina coated core/shell system exhibits the highest stability in terms of PLQY retention as well as the lowest shift of the PL maximum and lowest increase of the PL linewidth, followed by the CSS QDs and finally the gradient shell system. By means of XPS studies we identify the degradation of the ZnS outer layer and concomitant oxidation of the emissive InZnP core as the main origins of degradation in the gradient structure. These modifications do not occur in the case of the alumina-capped sample, which exhibits excellent chemical stability. The gradient shell and CSS systems could be transferred to the aqueous phase using surface ligand exchange with penicillamine. Cytotoxicity studies on human primary keratinocytes revealed that exposure for 24 h to 6.25–100 nM of QDs did not affect cell viability. However, a trend toward reduced cell proliferation is observed for higher concentrations of gradient shell and CSS QDs with a thin ZnS shell, while CSS QDs with a thicker ZnS shell do not exhibit any impact.