Nanodiamonds for In Vivo Applications

Multicomponent-assembled nanodiamond hybrids for targeted and imaging guided triple-negative breast cancer therapy via a ternary collaborative strategy

Uniting combinational strategies has been confirmed to be a robust choice for high-performance cancer treatment due to their abilities to overcome tumor heterogeneity and complexity. However, the development of a simple, effective, and multifunctional theranostics nanoplatform still remains a challenge. In this study, we integrated multicomponent hyaluronic acid (HA), protamine (PS), nanodiamonds (NDs), curcumin (Cur), and IR780 into a single nanoplatform (denoted as HPNDIC) based on the combination of hydrophobic and electrostatic noncovalent interactions for dual-modal fluorescence/photoacoustic imaging guided ternary collaborative Cur/photothermal/photodynamic combination therapy of triple-negative breast cancer (TNBC). A two-step coordination assembly strategy was utilized to realize this purpose. In the first step, PS was utilized to modify the NDs clusters to form positively charged PS@NDs (PND) and the simultaneous encapsulation of the natural small-molecule drug Cur and the photosensitive small-molecule IR780 (PNDIC). Second, HA was adsorbed onto the outer surface of the PNDIC through charge complexation for endowing a tumor-targeting ability (HPNDIC). The resulting HPNDIC had a uniform size, high drug-loading ability, and excellent colloidal stability. It was found that under the near-infrared irradiation condition, IR780 could be triggered to exhibit both PTT/PDT dual-pattern therapy effects, leading to an enhanced therapy efficiency of Cur both in vitro and in vivo with good biocompatibility. Due to the intrinsic imaging property of IR780, the biodistribution and accumulation behavior of HPNDIC in vivo could be monitored by dual-modal fluorescence/photoacoustic imaging. Taken together, our current work demonstrated the assembly of a NDs-based multicomponent theranostic platform for dual-modal fluorescence/photoacoustic imaging guided triple-collaborative Cur/photothermal/photodynamic against TNBC.

Biofilm inhibition in oral pathogens by nanodiamonds

Complex microbial communities, e.g., biofilms residing in our oral cavity, have recognized clinical significance, as they are typically the main cause for infections. Particularly, they show high resistance to conventional antibiotics, and alternatives including nanotechnology are being intensively explored nowadays to provide more efficient therapeutics. Diamond nanoparticles, namely, nanodiamonds (NDs) with many promising physico-chemical properties, have been demonstrated to work as an effective antibacterial agent against planktonic cells (free-floating state). However, little is known about the behaviors of NDs against biofilms (sessile state). In this study, we uncovered their role in inhibiting biofilm formation and their disrupting effect on preformed biofilms in several selected orally and systemically important organisms. The current findings will advance the mechanistic understanding of NDs on oral pathogens and might accelerate corresponding clinical translation.

Photoluminescent Nanomaterials for Medical Biotechnology

Creation of various photoluminescent nanomaterials has significantly expanded the arsenal of approaches used in modern biomedicine. Their unique photophysical properties can significantly improve the sensitivity and specificity of diagnostic methods, increase therapy effectiveness, and make a theranostic approach to treatment possible through the application of nanoparticle conjugates with functional macromolecules. The most widely used nanomaterials to date are semiconductor quantum dots; gold nanoclusters; carbon dots; nanodiamonds; semiconductor porous silicon; and up-conversion nanoparticles. This paper considers the promising groups of photoluminescent nanomaterials that can be used in medical biotechnology: in particular, for devising agents for optical diagnostic methods, sensorics, and various types of therapy.

Green Approaches to Carbon Nanostructure-Based Biomaterials

The family of carbon nanostructures comprises several members, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. Their unique electronic properties have attracted great interest for their highly innovative potential in nanomedicine. However, their hydrophobic nature often requires organic solvents for their dispersibility and processing. In this review, we describe the green approaches that have been developed to produce and functionalize carbon nanomaterials for biomedical applications, with a special focus on the very latest reports.

Nanodiamond Relaxometry-Based Detection of Free-Radical Species When Produced in Chemical Reactions in Biologically Relevant Conditions

Diamond magnetometry is a quantum sensing method involving detection of magnetic resonances with nanoscale resolution. For instance, T1 relaxation measurements, inspired by equivalent concepts in magnetic resonance imaging (MRI), provide a signal that is equivalent to T1 in conventional MRI but in a nanoscale environment. We use nanodiamonds (between 40 and 120 nm) containing ensembles of specific defects called nitrogen vacancy (NV) centers. To perform a T1 relaxation measurement, we pump the NV center in the ground state (using a laser at 532 nm) and observe how long the NV center can remain in this state. Here, we use this method to provide real-time measurements of free radicals when they are generated in a chemical reaction. Specifically, we focus on the photolysis of H₂O₂ as well as the so-called Haber–Weiss reaction. Both of these processes are important reactions in biological environments. Unlike other fluorescent probes, diamonds are able to determine spin noise from different species in real time. We also investigate different diamond probes and their ability to sense gadolinium spin labels. Although this study was performed in a clean environment, we take into account the effects of salts and proteins that are present in a biological environment. We conduct our experiments with nanodiamonds, which are compatible with intracellular measurements. We perform measurements between 0 and 10⁸ nM, and we are able to reach detection limits down to the nanomolar range and typically find T1 times of a few 100 μs. This is an important step toward label-free nano-MRI signal quantification in biological environments.

Coated nanodiamonds interact with tubulin beta-III negative cells of adult brain tissue

Fluorescent nanodiamonds (NDs) coated with therapeutics and cell-targeting structures serve as effective tools for drug delivery. However, NDs circulating in blood can eventually interact with the blood-brain barrier, resulting in undesired pathology. Here, we aimed to detect interaction between NDs and adult brain tissue. First, we cultured neuronal tissue with ND ex vivo and studied cell prosperity, regeneration, cytokine secretion, and nanodiamond uptake. Then, we applied NDs systemically into C57BL/6 animals and assessed accumulation of nanodiamonds in brain tissue and cytokine response. We found that only non-neuronal cells internalized coated nanodiamonds and responded by excretion of interleukin-6 and interferon-γ. Cells of neuronal origin expressing tubulin beta-III did not internalize any NDs. Once we applied coated NDs intravenously, we found no presence of NDs in the adult cortex but observed transient release of interleukin-1α. We conclude that specialized adult neuronal cells do not internalize plain or coated NDs. However, coated nanodiamonds interact with non-neuronal cells present within the cortex tissue. Moreover, the coated NDs do not cross the blood-brain barrier but they interact with adjacent barrier cells and trigger a temporary cytokine response. This study represents the first report concerning interaction of NDs with adult brain tissue.

Nanodiamonds for bioapplications, recent developments

The world of biomedical research is in constant evolution, requiring more and more conditions and norms through pre-clinic and clinic studies. Nanodiamonds (NDs) with exceptional optical, thermal and mechanical properties emerged on the global scientific scene and recently gained more attention in biomedicine and bioanalysis fields. Many problematics have been deliberated to better understand their in vitro and in vivo efficiency and compatibility. Light was shed on their synthesis, modification and purification steps, as well as particle size and surface properties in order to find the most suitable operating conditions. In this review, we present the latest advances of NDs use in bioapplications. A large variety of subjects including anticancer and antimicrobial systems, wound healing and tissue engineering management tools, but also bioimaging and labeling probes are tackled. The key information resulting from these recent works were evidenced to make an overview of the potential features of NDs, with a special look on emerging therapeutic and diagnosis combinations.

Effects of Fluorescent Diamond Particles FDP-NV-800nm on Essential Biochemical Functions of Primary Human Umbilical Vein Cells and Human Hepatic Cell Line, HepG-2 in vitro (Part VI): Acute Biocompatibility Studies

Background

Recently, we reported the safety and biocompatibility of fluorescent diamond particles, FDP-NV-Z-800nm (FDP-NV) injected intravenously into rats, where no morbidity and mortality were noted over a period of 3 months. The acute effects of FDP-NV-800nm particles on cultured human endothelial and hepatic cells remain unexplored.

Purpose

In this study, we aimed to explore select cellular and biochemical functions in cultured human umbilical endothelial cells (HUVEC) and a human hepatic cancer cell line (HepG-2) exposed to FDP-NV-800 in vitro at exposure levels within the pharmacokinetics (Cmax and the nadir) previously reported in vivo.

Methods

Diverse cellular and biochemical functions were monitored, which cumulatively can provide insights into some vital cellular functions. Cell proliferation and migration were assessed by quantitative microscopy. Mitochondrial metabolic functions were tested by the MTT assay, and cytosolic esterase activity was studied by the calcein AM assay. Chaperons (CHOP), BiP and apoptosis (caspase-3 activation) were monitored by using Western blot (WB). MAPK Erk1/2 signaling was assessed by the detection of the phosphorylated form of the protein (P-Erk 1/2) and its translocation into the cell nucleus.

Results

At all concentrations tested (0.001–0.1mg/mL), FDP-NV did not affect any of the biomarkers of cell integrity of HepG2 cells. In contrast, the proliferation of HUVEC was affected at the highest concentration tested (0.1mg/mL, C_max). Exposure of HUVEC to (0.01 mg/mL) FDP-NV had a mild-moderate effect on cell proliferation as evident in the MTT assay and was absent when proliferation was assessed by direct cell counting or by using the calcein AM assays. In both cell types, exposure to the highest concentration (0.1 mg/mL) of FDP-NV did neither affect FBS-stimulated cell signaling (MAPK Erk1/2 phosphorylation) nor did it activate of Caspase 3.

Conclusion

Our data suggest that FDP-NV-800nm are largely biocompatible with HepG-2 cells proliferation within the pharmacokinetic data reported previously. In contrast, HUVEC proliferation at the highest exposure dose (0.1 mg/mL) responded adversely with respect to several biomarkers of cell integrity. However, since the C_max levels are very short-living, the risk for endothelial injury is likely minimal for slow rate cell proliferation such as endothelial cells.

Multimodal Imaging and Soft X-Ray Tomography of Fluorescent Nanodiamonds in Cancer Cells

Multimodal imaging promises to revolutionize the understanding of biological processes across scales in space and time by combining the strengths of multiple imaging techniques. Fluorescent nanodiamonds (FNDs) are biocompatible, chemically inert, provide high contrast in light- and electron-based microscopy, and are versatile optical quantum sensors. Here it is demonstrated that FNDs also provide high absorption contrast in nanoscale 3D soft X-ray tomograms with a resolution of 28 nm in all dimensions. Confocal fluorescence, atomic force, and scanning electron microscopy images of FNDs inside and on the surface of PC3 cancer cells with sub-micrometer precision are correlated. FNDs are found inside ≈1 µm sized vesicles present in the cytoplasm, providing direct evidence of the active uptake of bare FNDs by cancer cells. Imaging artefacts are quantified and separated from changes in cell morphology caused by sample preparation. These results demonstrate the utility of FNDs in multimodal imaging, contribute to the understanding of the fate of FNDs in cells, and open up new possibilities for biological imaging and sensing across the nano- and microscale.

Targeting Nanodiamonds to the Nucleus in Yeast Cells

Nanodiamonds are widely used for drug delivery, labelling or nanoscale sensing. For all these applications it is highly beneficial to have control over the intracellular location of the particles. For the first time, we have achieved targeting the nucleus of yeast cells. In terms of particle uptake, these cells are challenging due to their rigid cell wall. Thus, we used a spheroplasting protocol to remove the cell wall prior to uptake. To achieve nuclear targeting we used nanodiamonds, which were attached to antibodies. When using non-targeted particles, only 20% end up at the nucleus. In comparison, by using diamonds linked to antibodies, 70% of the diamond particles reach the nucleus.

Recent Progress of Nanocarrier-Based Therapy for Solid Malignancies

Conventional chemotherapy is still an important option of cancer treatment, but it has poor cell selectivity, severe side effects, and drug resistance. Utilizing nanoparticles (NPs) to improve the therapeutic effect of chemotherapeutic drugs has been highlighted in recent years. Nanotechnology dramatically changed the face of oncology by high loading capacity, less toxicity, targeted delivery of drugs, increased uptake to target sites, and optimized pharmacokinetic patterns of traditional drugs. At present, research is being envisaged in the field of novel nano-pharmaceutical design, such as liposome, polymer NPs, bio-NPs, and inorganic NPs, so as to make chemotherapy effective and long-lasting. Till now, a number of studies have been conducted using a wide range of nanocarriers for the treatment of solid tumors including lung, breast, pancreas, brain, and liver. To provide a reference for the further application of chemodrug-loaded nanoformulations, this review gives an overview of the recent development of nanocarriers, and the updated status of their use in the treatment of several solid tumors.

Carbon Quantum Dots: In vitro and in vivo Studies on Biocompatibility and Biointeractions for Optical Imaging

BACKGROUND

Understanding the biocompatibility and biointeractions of nano-carbon quantum dots (nano-CQDs) in vitro and in vivo is important for assessing their potential risk to human health. In the previous research, the physical properties of CQDs synthesized by the laser ablation in liquid (LAL) method were analyzed in detail; however, possible bioapplications were not considered.

MATERIALS AND METHODS

CQDs were prepared by LAL and characterized by atomic force microscopy, fluorescence lifetime, absorption spectrum, Fourier-transform infrared spectroscopy, and dynamic light scattering. Their biocompatibility was evaluated in vitro using assays for cytotoxicity, apoptosis, and biodistribution and in vivo using immunotoxicity and the relative expression of genes. Cells were measured in vitro using fluorescence-lifetime imaging microscopy to analyze the biointeractions between CQDs and intracellular proteins.

RESULTS

There were no significant differences in biocompatibility between the CQDs and the negative control. The intracellular interactions had no impact on the optical imaging of CQDs upon intake by cells. Optical imaging of zebrafish showed the green fluorescence was well dispersed.

CONCLUSION

We have demonstrated that the CQDs have an excellent biocompatibility and can be used as efficient optical nanoprobes for cell tracking and biomedical labeling except for L929 and PC-3M cells.

Nanodiamond-enabled biomedical imaging

Biomedical imaging allows in vivo studies of organisms, providing valuable information of biological processes at both cellular and tissue levels. Nanodiamonds have recently emerged as a new type of probe for fluorescence imaging and contrast agent for magnetic resonance and photoacoustic imaging. Composed of sp3-carbon atoms, diamond is chemically inert and inherently biocompatible. Uniquely, its matrix can host a variety of optically and magnetically active defects suited for bioimaging applications. Since the first production of fluorescent nanodiamonds in 2005, a large number of experiments have demonstrated that fluorescent nanodiamonds are useful as photostable markers and nanoscale sensors in living cells and organisms. In this review, we focus our discussion on the recent advancements of nanodiamond-enabled biomedical imaging for preclinical applications.

Effect of medium and aggregation on antibacterial activity of nanodiamonds

Fluorescent nanodiamonds are widely used as abrasives, optical or magnetic labels, in drug delivery or nanoscale sensing. They are considered very biocompatible in mammalian cells. However, in bacteria the situation looks different and results are highly controversial. This article presents a short review of the published literature and a systematic experimental study of different strains, nanoparticle sizes and surface chemistries. Most notably, particle aggregation behaviour and bacterial clumping are taken into consideration to explain reduced colony counts, which can be wrongly interpreted as a bactericidal effect. The experiments show no mechanism can be linked to a specific material property, but prove that aggregation and bacteriostatic effect of nanodiamond attachment play a significant role in the reported results.

Therapeutic Nanoparticles and Their Targeted Delivery Applications

Nanotechnology offers many advantages in various fields of science. In this regard, nanoparticles are the essential building blocks of nanotechnology. Recent advances in nanotechnology have proven that nanoparticles acquire a great potential in medical applications. Formation of stable interactions with ligands, variability in size and shape, high carrier capacity, and convenience of binding of both hydrophilic and hydrophobic substances make nanoparticles favorable platforms for the target-specific and controlled delivery of micro- and macromolecules in disease therapy. Nanoparticles combined with the therapeutic agents overcome problems associated with conventional therapy; however, some issues like side effects and toxicity are still debated and should be well concerned before their utilization in biological systems. It is therefore important to understand the specific properties of therapeutic nanoparticles and their delivery strategies. Here, we provide an overview on the unique features of nanoparticles in the biological systems. We emphasize on the type of clinically used nanoparticles and their specificity for therapeutic applications, as well as on their current delivery strategies for specific diseases such as cancer, infectious, autoimmune, cardiovascular, neurodegenerative, ocular, and pulmonary diseases. Understanding of the characteristics of nanoparticles and their interactions with the biological environment will enable us to establish novel strategies for the treatment, prevention, and diagnosis in many diseases, particularly untreatable ones.

The Fate of Lipid-Coated and Uncoated Fluorescent Nanodiamonds during Cell Division in Yeast

Fluorescent nanodiamonds are frequently used as biolabels. They have also recently been established for magnetic resonance and temperature sensing at the nanoscale level. To properly use them in cell biology, we first have to understand their intracellular fate. Here, we investigated, for the first time, what happens to diamond particles during and after cell division in yeast (Saccharomyces cerevisiae) cells. More concretely, our goal was to answer the question of whether nanodiamonds remain in the mother cells or end up in the daughter cells. Yeast cells are widely used as a model organism in aging and biotechnology research, and they are particularly interesting because their asymmetric cell division leads to morphologically different mother and daughter cells. Although yeast cells have a mechanism to prevent potentially harmful substances from entering the daughter cells, we found an increased number of diamond particles in daughter cells. Additionally, we found substantial excretion of particles, which has not been reported for mammalian cells. We also investigated what types of movement diamond particles undergo in the cells. Finally, we also compared bare nanodiamonds with lipid-coated diamonds, and there were no significant differences in respect to either movement or intracellular fate.

3D tomographic magnetofluorescence imaging of nanodiamonds

We demonstrate lensless imaging of three-dimensional phantoms of fluorescent nanodiamonds in solution. Magnetofluorescence imaging is employed, which relies on a dependence of the fluorescence yield on the magnetic field, and pervading the object with an inhomogeneous magnetic field. This field provides a field-free field line, which is rastered through the object. A 3D image of the object is obtained by imaging a set of 2D slices. Each 2D slice image is computed from a set of 1D projections, obtained under different projection directions, using a backprojection algorithm. Reconstructed images containing up to 36 × 36 × 8 voxels are obtained. A spatial resolution better than 2 mm is achieved in three dimensions. The approach has the potential for scalability.

Nanoparticle-based Cell Trackers for Biomedical Applications

The continuous or real-time tracking of biological processes using biocompatible contrast agents over a certain period of time is vital for precise diagnosis and treatment, such as monitoring tissue regeneration after stem cell transplantation, understanding the genesis, development, invasion and metastasis of cancer and so on. The rationally designed nanoparticles, including aggregation-induced emission (AIE) dots, inorganic quantum dots (QDs), nanodiamonds, superparamagnetic iron oxide nanoparticles (SPIONs), and semiconducting polymer nanoparticles (SPNs), have been explored to meet this urgent need. In this review, the development and application of these nanoparticle-based cell trackers for a variety of imaging technologies, including fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, magnetic particle imaging, positron emission tomography and single photon emission computing tomography are discussed in detail. Moreover, the further therapeutic treatments using multi-functional trackers endowed with photodynamic and photothermal modalities are also introduced to provide a comprehensive perspective in this promising research field.

Carboxylated nanodiamond-mediated CRISPR-Cas9 delivery of human retinoschisis mutation into human iPSCs and mouse retina

Nanodiamonds (NDs) are considered to be relatively safe carbon nanomaterials used for the transmission of DNA, proteins and drugs. The feasibility of utilizing the NDs to deliver CRISPR-Cas9 system for gene editing has not been clearly studied. Therefore, in this study, we aimed to use NDs as the carriers of CRISPR-Cas9 components designed to introduce the mutation in RS1 gene associated with X-linked retinoschisis (XLRS). ND particles with a diameter of 3 nm were functionalized by carboxylation of the surface and covalently conjugated with fluorescent mCherry protein. Two linear DNA constructs were attached to the conjugated mCherry: one encoded Cas9 endonuclease and GFP reporter, another encoded sgRNA and contained insert of HDR template designed to introduce RS1 c.625C>T mutation. Such nanoparticles were successfully delivered and internalized by human iPSCs and mouse retinas, the efficiency of internalization was significantly improved by mixing with BSA. The delivery of ND particles led to introduction of RS1 c.625C>T mutation in both human iPSCs and mouse retinas. Rs1 gene editing in mouse retinas resulted in several pathological features typical for XLRS, such as aberrant photoreceptor structure. To conclude, our ND-based CRISPR-Cas9 delivery system can be utilized as a tool for creating in vitro and in vivo disease models of XLRS. STATEMENT OF SIGNIFICANCE: X-linked retinoschisis (XLRS) is a prevalent hereditary retinal disease, which is caused by mutations in RS1 gene, whose product is important for structural organization of the retina. The recent development of genome editing techniques such as CRISPR-Cas9 significantly improved the prospects for better understanding the pathology and development of treatment for this disease. Firstly, gene editing can allow development of appropriate in vitro and in vivo disease models; secondly, CRISPR-Cas9 can be applied for gene therapy by removing the disease-causative mutation in vivo. The major prerequisite for these approaches is to develop safe and efficient CRISPR-Cas9 delivery system. In this study, we tested specifically modified nanodiamonds for such a delivery system. We were able to introduce Rs1 mutation into the mouse retina and, importantly, observed several XLRS-specific effects.

A redox-sensitive core-crosslinked nanosystem combined with ultrasound for enhanced deep penetration of nanodiamonds into tumors

Nanodiamonds (NDs) as drug delivery vehicles are of great significance in anticancer therapy through enhancing drug retention. However, the major barrier to clinical application of NDs is insufficient tumor penetration owing to their strong aggregation and low passive penetration efficiency. Herein, the core-crosslinked pullulan carrier, assembled using the visible light-induced diselenide (Se–Se) bond crosslinking method for encapsulating nanodiamonds-doxorubicin (NDX), is proposed to improve monodispersity. Furthermore, the core-crosslinked diselenide bond provides the nanosystem with redox-responsive capability and improved structural stability in a physiological environment, which prevents premature drug leakage and achieves tumor site-specific controlled release. What's more, ultrasound (US) is utilized to promote nanosystem intratumoral penetration via enlarged tumor vascular endothelium cell gaps. As expected, the nanosystem combined with ultrasound can enhance anti-tumor efficacy with deep penetration and excellent retention performance in a HepG2 xenograft mouse model. This study highlights the ability of the integrated therapeutic paradigm to overcome the limitation of nanodiamonds and the potential for further application in cancer therapy.

A redox-sensitive core-crosslinked nanosystem is developed as a drug vehicle combined with ultrasound for efficient enhanced deep penetration of nanodiamonds into tumors.

Nanodiamond-Based Theranostic Platform for Drug Delivery and Bioimaging

Nanodiamonds (NDs) are promising candidates for biomedical application due to their excellent biocompatibility and innate physicochemical properties. In this Concept article, nanodiamond-based theranostic platforms, which combine both drug delivery features and bioimaging functions, are discussed. The latest developments of therapeutic strategies are introduced and future perspectives for theranostic NDs are addressed.

A Perspective on Fluorescent Nanodiamond Bioimaging

The field of fluorescent nanodiamonds (FNDs) has advanced greatly over the past few years. Though historically limited primarily to red fluorescence, the wavelengths available for nanodiamonds have increased due to continuous technical advancement. This Review summarizes the strides made in the synthesis, functionalization, and application of FNDs to bioimaging. Highlights range from super-resolution microscopy, through cellular and whole animal imaging, up to constantly emerging fields including sensing and hyperpolarized magnetic resonance imaging.

Combined toxicity of graphite-diamond nanoparticles and thiabendazole to Daphnia magna

Carbon-based nanomaterials exhibit unique properties that make them suitable for a wide variety of industrial and biomedical applications. In this work, we studied the acute toxicity of graphite-diamond nanoparticles (GDN) combined with the fungicide thiabendazole (TBZ) to the immobilization of the cladoceran Daphnia magna in the presence and absence of the micro green algae Raphidocelis subcapitata, supplied as food source. The toxicity of GDN to D. magna decreased in the presence of R. subcapitata, while that of TBZ increased, the latter suggesting a carrier effect to TBZ. GDN-TBZ mixtures were fitted to the most common conceptual models applied to mixture toxicity: Concentration Addition (CA), Independent Action (IA) and Combination Index (CI). For GDN-TBZ mixtures in the absence of food the best fit was obtained with dose ratio deviation from CA model, while in the presence of food, dose level deviation from CA gave a better fit. The binary mixtures of GDN and TBZ showed synergistic toxic interactions at low concentrations, which could be attributed to the increased bioavailability of TBZ adsorbed on GDN. For higher concentrations of GDN, the binary mixtures turned antagonistic due to particle agglomeration. Our study provides evidence that deviations from additivity are dose dependent and relevant for the risk assessment of mixtures of nanoparticles with other chemical pollutants.

The effect of particle size on nanodiamond fluorescence and colloidal properties in biological media

Fluorescent nanodiamonds (FNDs) are extremely photostable markers and nanoscale sensors, which are increasingly used in biomedical applications. Nanoparticle size is a critical parameter in the majority of these applications. Yet, the effect of particle size on FND's fluorescence and colloidal properties is not well understood today. Here, we investigate the fluorescence and colloidal stability of commercially available high-pressure high-temperature FNDs containing nitrogen-vacancy (NV) centers in biological media. Unconjugated FNDs in sizes ranging between 10 nm and 140 nm with an oxidized surface are studied using dynamic light scattering and fluorescence spectroscopy. We determine their colloidal stability in water, fetal bovine serum, Dulbecco's Modified Eagle Medium and complete media. The FNDs' relative fluorescence brightness, the NV charge-state, and the FND fluorescence against media autofluorescence are analyzed as a function of FND size. Our results will enable researchers in biology and beyond to identify the most promising FND particle size for their application.

Biocompatibility studies of fluorescent diamond particles-(NV)~800nm (part V): in vitro kinetics and in vivo localization in rat liver following long-term exposure

Background

We recently reported on long-term comprehensive biocompatibility and biodistribution study of fluorescent nanodiamond particles (NV)-Z-average 800nm (FNDP-(NV)) in rats. FNDP-(NV) primary deposition was found in the liver, yet liver function tests remained normal.

Purpose

The present study aimed to gain preliminary insights on discrete localization of FNDP-(NV) in liver cells of the hepatic lobule unit and venous micro-vasculature. Kinetics of FDNP-(NV) uptake into liver cells surrogates in culture was conducted along with cell cytokinesis as markers of cells' viability.

Methods

Preserved liver specimens from a pilot consisting of two animals which were stained for cytoskeletal elements (fluorescein-isothiocyanate-phalloidin) were examined for distribution of FNDP-(NV) by fluorescent microscopy (FM) and Confocal-FM (CFM) using near infra-red fluorescence (NIR). Hepatocellular carcinoma cells (HepG-2) and human umbilical vein endothelial cells (HUVEC) were cultured with FNDP-(NV) and assayed for particle uptake and location using spectrophotometric technology and microscopy.

Results

HepG-2 and HUVEC displayed rapid (<30 mins) onset and concentration-dependent FNDP-(NV) internalization and formation of peri-nuclear corona. FM/CFM of liver sections revealed FNDP-(NV) presence throughout the hepatic lobules structures marked by spatial distribution, venous microvascular spaces and parenchyma and non-parenchyma cells.

Conclusion

The robust presence of FNDP-(NV) throughout the hepatic lobules including those internalized within parenchyma cells and agglomerates in the liver venous micro-circulation were not associated with macro or micro histopathological signs nor vascular lesions. Cells cultures indicated normal cytokinesis in cells containing FNDP-(NV) agglomerates. Liver parenchyma cells and the liver microcirculation remain agnostic to presence of FNDP-(NV) in the sinusoids or internalized in the hepatic cells.

Knockdown of microRNA-135b in Mammary Carcinoma by Targeted Nanodiamonds: Potentials and Pitfalls of In Vivo Applications

Nanodiamonds (ND) serve as RNA carriers with potential for in vivo application. ND coatings and their administration strategy significantly change their fate, toxicity, and effectivity within a multicellular system. Our goal was to develop multiple ND coating for effective RNA delivery in vivo. Our final complex (NDA135b) consisted of ND, polymer, antisense RNA, and transferrin. We aimed (i) to assess if a tumor-specific coating promotes NDA135b tumor accumulation and effective inhibition of oncogenic microRNA-135b and (ii) to outline off-targets and immune cell interactions. First, we tested NDA135b toxicity and effectivity in tumorospheres co-cultured with immune cells ex vivo. We found NDA135b to target tumor cells, but it binds also to granulocytes. Then, we followed with NDA135b intravenous and intratumoral applications in tumor-bearing animals in vivo. Application of NDA135b in vivo led to the effective knockdown of microRNA-135b in tumor tissue regardless administration. Only intravenous application resulted in NDA135b circulation in peripheral blood and urine and the decreased granularity of splenocytes. Our data show that localized intratumoral application of NDA135b represents a suitable and safe approach for in vivo application of nanodiamond-based constructs. Systemic intravenous application led to an interaction of NDA135b with bio-interface, and needs further examination regarding its safety.

Applications of Nanodiamonds in the Detection and Therapy of Infectious Diseases

We are constantly exposed to infectious diseases, and they cause millions of deaths per year. The World Health Organization (WHO) estimates that antibiotic resistance could cause 10 million deaths per year by 2050. Multidrug-resistant bacteria are the cause of infection in at least one in three people suffering from septicemia. While antibiotics are powerful agents against infectious diseases, the alarming increase in antibiotic resistance is of great concern. Alternatives are desperately needed, and nanotechnology provides a great opportunity to develop novel approaches for the treatment of infectious diseases. One of the most important factors in the prognosis of an infection caused by an antibiotic resistant bacteria is an early and rigorous diagnosis, jointly with the use of novel therapeutic systems that can specifically target the pathogen and limit the selection of resistant strains. Nanodiamonds can be used as antimicrobial agents due to some of their properties including size, shape, and biocompatibility, which make them highly suitable for the development of efficient and tailored nanotherapies, including vaccines or drug delivery systems. In this review, we discuss the beneficial findings made in the nanodiamonds field, focusing on diagnosis and treatment of infectious diseases. We also highlight the innovative platform that nanodiamonds confer for vaccine improvement, drug delivery, and shuttle systems, as well as their role in the generation of faster and more sensitive clinical diagnosis.

Targeting EGFR of triple-negative breast cancer enhances the therapeutic efficacy of paclitaxel- and cetuximab-conjugated nanodiamond nanocomposite

Breast cancer is the most common malignancy and a leading cause of cancer-related mortality among women worldwide. Triple-negative breast cancer (TNBC) is characterized by the lack of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2). However, epidermal growth factor receptor (EGFR) is highly expressed in most of the TNBCs, which may provide a potential target for EGFR targeting therapy. Nanodiamond (ND) is a carbon-based nanomaterial with several advantages, including fluorescence emission, biocompatibility, and drug delivery applications. In this study, we designed a nanocomposite by using ND conjugated with paclitaxel (PTX) and cetuximab (Cet) for targeting therapy on the EGFR-positive TNBC cells. ND-PTX inhibited cell viability and induced mitotic catastrophe in various human breast cancer cell lines (MDA-MB-231, MCF-7, and BT474); in contrast, ND alone did not induce cell death. ND-PTX inhibited the xenografted human breast tumors in nude mice. We further investigated ND-PTX-Cet drug efficacy on the TNBC of MDA-MB-231 breast cancer cells. ND-PTX-Cet could specifically bind to EGFR and enhanced the anticancer effects including drug uptake levels, mitotic catastrophe, and apoptosis in the EGFR-expressed MDA-MB-231 cells but not in the EGFR-negative MCF-7 cells. In addition, ND-PTX-Cet increased the protein levels of active caspase-3 and phospho-histone H3 (Ser10). Furthermore, ND-PTX-Cet showed more effective on the reduction of TNBC tumor volume by comparison with ND-PTX. Taken together, these results demonstrated that ND-PTX-Cet nanocomposite enhanced mitotic catastrophe and apoptosis by targeting EGFR of TNBC cells, which can provide a feasible strategy for TNBC therapy. STATEMENT OF SIGNIFICANCE: Current TNBC treatment is ineffective against the survival rate of TNBC patients. Therefore, the development of new treatment strategies for TNBC patients is urgently needed. Here, we have designed a nanocomposite by targeting on the EGFR of TNBC to enhance therapeutic efficacy by ND-conjugated PTX and Cet (ND-PTX-Cet). Interestingly, we found that the co-delivery of Cet and PTX by ND enhanced the apoptosis, mitotic catastrophe and tumor inhibition in the EGFR-expressed TNBC in vitro and in vivo. Consequently, this nanocomposite ND-PTX-Cet can be applied for targeting EGFR of human TNBC therapy.

Fluorescent Fe Embedded Magnetic Nanodiamonds Made by Ion Implantation

We demonstrate fluorescent Fe embedded magnetic nanodiamonds by ion implantation and two-step annealing. The diamond characteristics with a highly ordered core and a graphite surface layer are maintained after the implantation process. After the two-step annealing process, a bright red fluorescence associated with nitrogen-vacancy centers is observed. These new fluorescent magnetic nanodiamonds can be used as a dual-function in vivo tracer with both optical visibility and magnetic resonance imaging capabilities. They are potentially useful for the more advanced in vivo biological and medical applications.

Nanosensors for diagnosis with optical, electric and mechanical transducers

Nanosensors with high sensitivity utilize electrical, optical, and acoustic properties to improve the detection limits of analytes.

Toward Using Fluorescent Nanodiamonds To Study Chronological Aging in Saccharomyces cerevisiae

One of the theories aiming to explain cellular aging is the free radical theory of aging, which describes the possible role of increased production and accumulation of free radicals. Fluorescent nanodiamonds (FNDs) are proposed to provide a tool to detect these radicals, as they function as magnetic sensors that change their optical properties depending on their magnetic surrounding. Therefore, they could enable the study of aging at a molecular level and unravel the exact role of free radicals in this process. In this study, important steps toward this goal are made. FNDs are introduced in chronologically aging yeast cells. Furthermore, the behavior of FNDs in these aging cells is studied to demonstrate the potency of using FNDs in the search for causes of cellular aging.

Chronic toxicity of nanodiamonds can disturb development and reproduction of Acheta domesticus L

The use of nanodiamonds in numerous materials designed for industry and medicine is growing rapidly. Consequently health and environmental risks associated with the exposure of humans and other biota to nanodiamonds-based materials are of the utmost importance. Scarcity of toxicological data for these particles led us to examine the potentially deleterious effects of nanodiamonds in model insect species, Acheta domesticus (Orthoptera) chronically exposed to ND in its diet. Organism-level end-point indices (lifespan, body weight, consumption, caloric value of faeces, reproduction) revealed adverse changes in the treated crickets in comparison with the control. Preliminary studies of oxidative stress level in the offspring of ND-treated crickets suggest toxicity of these particles limited to the exposed individuals. EPR analysis showing increase of radical signal in the faeces of ND-fed crickets led us to propose novel mechanism of nanodiamonds toxicity that is discussed in the light of literature data.

CAPSULE

Development and reproduction of Acheta domesticus can be disturbed by the chronic exposure to nanodiamonds.

Interaction of nanodiamonds with bacteria

Nanocarbons come in many forms and among their applications is the engineering of biocompatible and antibacterial materials. Studies have shown that diamond nanoparticles might have the interesting combination of both properties: they are highly biocompatible, while surprisingly reducing bacterial viability or growth at the same time. In this article, we consider for the first time the interaction of milled HPHT nanodiamonds with bacteria. These nanoparticles are capable of hosting nitrogen-vacancy (NV) centers, which provide stable fluorescence with potential use in sensing applications. An initial study was performed to assess the interaction of partially oxidized monocrystalline nanodiamonds with Gram positive S. aureus ATCC 12600 and Gram negative E. coli ATCC 8739. It was shown that for S. aureus ATCC 12600, the presence of these nanodiamonds leads to a sharp reduction of colony forming ability under optimal conditions. A different effect was observed on Gram negative E. coli ATCC 8739, where no significant adverse effects of ND presence was observed. The mode of interaction was further studied by electron microscopy and confocal microscopy. The effects of NDs on S. aureus viability were found to depend on many factors, including the concentration and size of nanoparticles, the suspension medium and incubation time.

Fe Doped Magnetic Nanodiamonds Made by Ion Implantation as Contrast Agent for MRI

We report in this paper a new MRI contrast agent based on magnetic nanodiamonds fabricated by Fe ion implantation. The Fe atoms that are implanted into the nanodiamonds are not in direct contact with the outside world, enabling this new contrast agent to be free from cell toxicity. The image enhancement was shown clearly through T2 weighted images. The concentration dependence of the T2 relaxation time gives a relaxivity value that is about seven times that of the regular non-magnetic nanodiamonds. Cell viability study has also been performed. It was shown that they were nearly free from cytotoxicity independent of the particle concentration used. The imaging capability demonstrated here adds a new dimension to the medical application of nanodiamonds. In the future one will be able to combine this capability of magnetic nanodiamonds with other functions through surface modifications to perform drug delivery, targeted therapy, localized thermal treatment and diagnostic imaging at the same time.

The Response of HeLa Cells to Fluorescent NanoDiamond Uptake

Fluorescent nanodiamonds are promising probes for nanoscale magnetic resonance measurements. Their physical properties predict them to have particularly useful applications in intracellular analysis. Before using them in intracellular experiments however, it should be clear whether diamond particles influence cell biology. While cytotoxicity has already been ruled out in previous studies, we consider the non-fatal influence of fluorescent nanodiamonds on the formation of reactive oxygen species (an important stress indicator and potential target for intracellular sensing) for the first time. We investigated the influence of different sizes, shapes and concentrations of nanodiamonds on the genetic and protein level involved in oxidative stress-related pathways of the HeLa cell, an important model cell line in research. The changes in viability of the cells and the difference in intracellular levels of free radicals, after diamond uptake, are surprisingly small. At lower diamond concentrations, the cellular metabolism cannot be distinguished from that of untreated cells. This research supports the claims of non-toxicity and includes less obvious non-fatal responses. Finally, we give a handhold concerning the diamond concentration and size to use for non-toxic, intracellular measurements in favour of (cancer) research in HeLa cells.