Disposable biosensor based on nanodiamond particles, ionic liquid and poly-l-lysine for determination of phenolic compounds

This study describes the development of a highly sensitive amperometric biosensor for the analysis of phenolic compounds such as catechol. The biosensor architecture is based on the immobilization of tyrosinase (Tyr) on a screen-printed carbon electrode (SPE) modified with nanodiamond particles (ND), 1-butyl-3-methylimidazolium hexafluorophosphate (IL) and poly-l-lysine (PLL). Surface morphologies of the electrodes during the modification process were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical characteristics of the modified electrodes. Owing to the synergistic effect of the modification materials, the Tyr/PLL/ND-IL/SPE exhibited high sensitivity (328.2 μA mM-1) towards catechol with a wide linear range (5.0 × 10-8 - 1.2 × 10-5 M) and low detection limit (1.1 × 10-8 M). Furthermore, the method demonstrated good reproducibility and stability. The amperometric response of the biosensor towards other phenolic compounds such as bisphenol A, phenol, p-nitrophenol, m-cresol, p-cresol and o-cresol was also investigated. The analytical applicability of the biosensor was tested by the analysis of catechol in tap water. The results of the tap water analysis showed that the Tyr/PLL/ND-IL/SPE can be used as a practical and effective method for catechol determination.

Eudragit S100 coated nanodiamond-based nanoparticles as an oral chemo-photothermal delivery system for local treatment of colon cancer

Oral colonic nano-drug delivery system has received more and more attention in the treatment of colon cancer due to local precision treatment and reduction of drug system distribution. However, the complex and harsh gastrointestinal environment and the retention of nanoparticles in the colon limit its development. To this end, we designed Eudragit S100 (ES) coated nanoparticles (ES@PND-PEG-TPP/DOX). Polydopamine coated nanodiamond (PND) was modified with amino-functionalized polyethylene glycol (NH2-PEG-NH2) and triphenylphosphine (TPP) successively. Due to the high specific surface area of PND, it can efficiently load the model drug doxorubicin hydrochloride (DOX). In addition, PND also has high photothermal conversion efficiency, generating heat to kill cancer cells under near infrared (NIR) laser, realizing the combination of chemotherapy and photothermal therapy (CT-PTT). TPP modification enhanced nanoparticle uptake by colon cancer cells and prolonged preparations retention time at the colon. ES shell protected the drug from being destroyed and prevented the nanoparticles from sticking to the small intestine. Ex vitro fluorescence imaging showed that TPP modification can enhance the residence time of nanoparticles in the colon. In vivo pharmacodynamics demonstrated that CT-PTT group has the greatest inhibitory effect on tumor growth, which means that the nanocarrier has potential clinical value in the in-situ treatment of colon cancer.

In situ detection of dopamine in single living cells by molecularly imprinted polymer-functionalized nanoelectrodes

In situ detection of dopamine (DA) at single-cell level is critical for exploring neurotransmitter-related biological processes and diseases. However, the low content of DA and a variety of distractors with similar oxidation potentials as DA in cells brought great challenges. Here, a sensitive and specific electrochemical nanosensor was proposed for in situ detection of DA in single living cells based on nanodiamond (ND) and molecularly imprinted polymer (MIP)-functionalized carbon fiber nanoelectrode (ND/MIP/CFNE). Due to its excellent electrocatalytic property, ND was modified to the surface of CFNE based on amide bonding. Compared with bare CFNE, ND-modified CFNE can enhance oxidation currents of DA by about 4-fold, improving signal-to-noise ratio and detection sensitivity. MIP was further electropolymerized on the surface of nanoelectrodes to achieve specific capture and recognition of DA, which could avoid the interference of complex matrix and analogs in cells. Taking advantage of the precise positioning capability of a single-cell analyzer and micromanipulator, ND/MIP/CFNE could be precisely inserted into different locations of single cells and monitor oxidation signal of DA. The concentration of DA in the cytoplasm of single pheochromocytoma (PC12) cell was measured to be about 0.4 μM, providing a sensitive and powerful method for single-cell detection. Furthermore, the nanoelectrodes can monitor the fluctuation of intracellular DA under drug stimulation, providing new ideas and methods for new drug development and efficacy evaluation.

Preparation of nanodiamond anchored on copper tannic acid as a heterogenous catalyst for synthesis of 1,4-benzodiazepines derivatives

In this research, a new and eco-friendly heterogeneous catalyst (ND@Tannicacid-Cu) was synthesized based on nanodiamond and copper tannic acid via esterification process. The as-prepared catalyst was characterized by Fourier transforms infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD) methods. The catalytic efficacy of the intended catalyst was examined by one-step three-component reaction of 1,4-benzodiazepine derivatives from a mixture of ortho-phenylenediamine, aromatic aldehydes, and dimedone under mild conditions. In all instances, corresponding 2,4-benzodiazepines derivatives were synthesized with high efficiency, short reaction time, straightforward work up procedure, no requirement for column-chromatography, and cost-effective catalyst. The heterogeneous catalyst was easily recycled using fillers, and it can be reused for eight cycles without significantly diminishing its performance.

Bottom-up strategy of multi-level structured boron-doped diamond for the durable electrode in water purification

Long-term exposition of electrodes to aqueous media inevitably results in biofouling and adhesion of bacteria, reducing the electrolysis efficiency of electrodes for water treatment. To ensure technically efficient antifouling of materials for durable electrodes, hierarchical micro-/nano structured boron-doped diamond (BDD) electrodes were designed and synthesized. Multi-level structured BDD was coated on titanium mesh by a bottom-up strategy, based on a combination of self-assembly seeding and hot filament chemical vapor deposition (HFCVD) growth. The morphology of the BDD coating can be controlled by manipulating the seeding density and boron doping concentration. The designed micro/nano hierarchical structure of the BDD electrode suppressed bacterial adhesion greatly and exhibited excellent anti-biofouling efficiency with an antibacterial rate of ∼ 93 %, which entails simplified self-cleaning and durable BDD-coated electrodes. The BDD-coated electrodes were employed to electrochemically treat Escherichia coli-contaminated water, killing virtually all bacteria (≥99.9 %) in 1 min. Finally, real river water was electrochemically treated, reducing the chemical oxygen demand (COD) down to 5 mg/L in 4 h. The excellent performance shows the great potential of the structured BDD electrodes for long-term water purification.

Nanodiamond (ND)-Based ND@CuAl2O4@Fe3O4 electrochemical sensor for Tofacitinib detection: A unified approach to integrate experimental data with DFT and molecular docking

Tofacitinib (TOF) is gaining recognition as a potent therapeutic agent for a variety of autoimmune disorders, including rheumatoid arthritis and psoriasis. Ensuring precise drug concentration control during treatment necessitates a rapid and sensitive detection method. This study introduces a novel electrochemical sensor employing a composite of nanodiamond (ND), copper aluminate spinel oxide (CuAl2O4), and iron (II, III) oxide (Fe3O4) as modified materials for efficient TOF detection. Extensive analyses using physicochemical and electrochemical techniques were carried out to characterize the morphological, structural, and electrochemical properties of the ND@CuAl2O4@Fe3O4 composite. Thereafter, various voltammetric methods were utilized to evaluate the electrochemical behavior of the ND@CuAl2O4@Fe3O4-modified glassy carbon electrode (GCE) concerning TOF determination. The fabricated electrode showcased superior performance in electrochemical TOF detection in a buffered solution (pH = 5), achieving a remarkably low detection limit of 7.8 nM and a linear response from 0.05 μM to 13.21 μM. Furthermore, applying the modified electrode as an electrochemical sensor exhibited exceptional selectivity, stability, and practicality in determining TOF in pharmaceutical and biological samples. Alongside the sensor development, this study conducted a thorough investigation using Density Functional Theory (DFT) for the geometry optimization of TOF and the TOF-ND complex. Consequently performed molecular docking studies using Janus Kinase 1 (JAK1) (PDB ID: 3EYG) and JAK3 (PDB ID: 3LXK) indicated higher interaction of the TOF-ND conjugate with the JAKs, reflected by binding energies of -12.9 kcal/mol and -11.7 kcal/mol for JAK1 and JAK3 respectively, compared to -7.0 kcal/mol and -6.9 kcal/mol for TOF alone. These findings illustrate the potential of the ND-based ND@CuAl2O4@Fe3O4 composite as a proficient sensing material for TOF detection and the merits of DFT in providing a detailed understanding of the interactions at play. This pioneering research holds promise for real-time TOF monitoring, which will advance personalized treatment strategies and improve therapeutic outcomes for patients with autoimmune disorders.

Complex Three-Dimensional Microscale Structures for Quantum Sensing Applications

We present a novel method for fabricating highly customizable three-dimensional structures hosting quantum sensors based on nitrogen vacancy (NV) centers using two-photon polymerization. This approach overcomes challenges associated with structuring traditional single-crystal quantum sensing platforms and enables the creation of complex, fully three-dimensional, sensor assemblies with submicroscale resolutions (down to 400 nm) and large fields of view (>1 mm). By embedding NV center-containing nanoparticles in exemplary structures, we demonstrate high sensitivity optical sensing of temperature and magnetic fields at the microscale. Our work showcases the potential for integrating quantum sensors with advanced manufacturing techniques, facilitating the incorporation of sensors into existing microfluidic and electronic platforms, and opening new avenues for widespread utilization of quantum sensors in various applications.

Innovative electrochemical platform for the simultaneous determination of L-DOPA and L-tyrosine using layer-by-layer assembled L-proline-linked nanodiamonds on printed graphene

Discovering alternative analytical techniques is crucial for practical applications; thus, this work aims to develop an innovative and simple electrochemical sensor for melanoma and the clinical diagnosis of related disorders by the simultaneous determination of 3,4-dihydroxy-L-phenylalanine (L-DOPA) and L-tyrosine (L-Tyr). The fabrication is based on the layer-by-layer electrodeposition of poly L-proline (poly(L-pro)) and nanodiamond (ND) onto a screen-printed graphene electrode (SPGE). The poly(L-pro)/ND/SPGEs were morphologically characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and Raman spectroscopy followed by electrochemical investigation using cyclic voltammetry, differential pulse voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. These modifier-based electrodes pave a feasible way to unlock the coexisting interfering substances from screen-printing ink composition and improve the sensitivity. Additionally, computational chemistry calculations were performed to fully comprehend the sensing behavior on both target analytes. Under optimal conditions, the developed sensor provided linear concentration ranges of 0.075-50 μM, with a detection limit of 0.021 μM for L-DOPA, and 2.5-120 μM with a detection limit of 0.74 μM for L-Tyr. To demonstrate the reliability of the poly(L-pro)/ND/SPGE in practical application, it was successfully applied to the determination of these analytes in human urine and blood serum samples, with satisfactory recovery ranges (81.73-110.62% for L-DOPA and 82.17-110.01% for L-Tyr) and relative standard deviations (0.69-9.90% for L-DOPA and 0.40-9.55% for L-Tyr). Due to its simplicity, long-term stability (> 87.8% of their initial currents after 35 days), and portability, the developed sensor is a promising alternative analytical method for on-site clinical monitoring.

Effect of sp3/sp2 carbon ratio and hydrodynamic size on the biodistribution kinetics of nanodiamonds in mice via intravenous injection

BACKGROUND

Nanodiamonds (NDs) have gained a rapidly growing interest in biomedical applications; however, little is known regarding their biokinetics owing to difficulties in measurements and limited synthesis/purification technologies. In this study, we investigated the distribution kinetics of detonation-synthesized NDs in mice via intravenous injection to evaluate the parameters that determine the behavior of the particles. We prepared two distinctive NDs that controlled the sp3/sp2 carbon ratio and particle size by coating them with serum proteins. The four control samples were intravenously injected into mice, and tissue distribution and clearance were evaluated at 30 min and 1, 7, and 28 days post-injection.

RESULTS

The sp3/sp2 carbon ratio showed no correlation with the organ distribution of the NDs. However, hydrodynamic size showed an excellent correlation with organ distribution levels: a negative correlation in the liver and positive correlations in the spleen and lungs. Furthermore, the deposition levels of NDs in the lung suggest that particles smaller than 300 nm could avoid lung deposition. Finally, a similar organ distribution pattern was observed in mice injected with carbon black nanoparticles controlled hydrodynamic size.

CONCLUSIONS

In conclusion, the tissue distribution of NDs is modulated not by the sp3/sp2 carbon ratio but by the hydrodynamic size, which can provide helpful information for targeting the tissue of NDs. Furthermore, the organ distribution pattern of the NDs may not be specific to NDs but also can apply to other nanoparticles, such as carbon black.

Covalent conjugates based on nanodiamonds with doxorubicin and a cytostatic drug from the group of 1,3,5-triazines: Synthesis, biocompatibility and biological activity

We report the synthesis of covalent conjugates of nanodiamonds with doxorubicin and a cytostatic drug from the class of 1,3,5-triazines. The obtained conjugates were identified using a number of physicochemical methods (IR-spectroscopy, NMR-spectroscopy, XRD, XPS, TEM). As a result of our study, it was found that ND-СONH-Dox and ND-COO-Diox showed good hemocompatibility, since they did not affect plasma coagulation hemostasis, platelet functional activity, and erythrocyte membrane. The ND-COO-Diox conjugates are also capable of binding to human serum albumin due to the presence of ND in their composition. In the study of the cytotoxic properties of ND-СONH-Dox and ND-COO-Diox in the T98G glioblastoma cell line, indicating that ND-СONH-Dox and ND-COO-Diox demonstrate greater cytotoxicity at lower concentrations of Dox and Diox in the composition of the conjugates compared to individual drugs; the cytotoxic effect of ND-COO-Diox was statistically significantly higher than that of ND-СONH-Dox at all concentrations studied. Greater cytotoxicity at lower concentrations of Dox and Diox in the composition of conjugates compared to individual cytostatics makes it promising to further study the specific antitumor activity and acute toxicity of these conjugates in models of glioblastoma in vivo. Our results demonstrated that ND-СONH-Dox and ND-COO-Diox enter HeLa cells predominantly via a nonspecific actin-dependent mechanism, while for ND-СONH-Dox a clathrin-dependent endocytosis pathway. All data obtained provide that the synthesized nanomaterials show a potential application as the agents for intertumoral administration.

Efficient removal of heavy metal ions from aqueous media by unmodified and modified nanodiamonds

This article deals with the adsorption performances of the unmodified nanodiamond (ND) and thermally oxidized nanodiamond (Ox-ND) for the removal of different heavy metal ions such as Fe (III), Cu (II), Cr (VI), and Cd (II) from wastewater. The adsorption capacities of the ions onto adsorbents are higher and follow the order: Ox-ND-3 > Ox-ND-1.5 > ND, which is consistent with their surface areas, zeta potentials, and the presence of carboxyl groups, suggesting that electrostatic attractions between the positive metal ions and the negatively charged adsorbents are the predominant adsorption mechanisms. Adsorption capacities of these adsorbents were found to be 26.8, 31.3, and 45.7 mg/g for Fe (III), 25.2, 30.5, and 44.5 mg/g for Cu (II), 33.6, 44.1, and 55.9 mg/g for Cr (VI), and 40.9, 52.9, and 67.9 mg/g for Cd (II) over ND, Ox-ND-1.5, and Ox-ND-3, respectively. The impact of various operating parameters such as agitation time, initial metal ion concentration, temperature, pH solution, adsorbent dosage, and coexistence of the metal ions on the adsorption performance of Ox-ND-3 towards Cd (II) ions along with the batch adsorption experiments were performed. The equilibrium was reached in 120 min and adsorption data were fitted well with the pseudo-second-order kinetic as well as the Freundlich isotherm models. Adsorption process was spontaneous and exothermic, while the maximum removal efficiency of Cd (II) ions occurred at pH of 6.9 and at 4 g/L dosage. These findings demonstrated that thermally oxidized nanodiamond (Ox-ND) can be a versatile adsorbent to remove the Cd (II) ions from wastewater.

Nanodiamond enhanced mechanical and biological properties of extrudable gelatin hydrogel cross-linked with tannic acid and ferrous sulphate

Background

The requirements for cell-encapsulated injectable and bioprintable hydrogels are extrusion ability, cell supportive micro-environment and reasonable post-printing stability for the acclimatization of the cells in the target site. Detonation nanodiamond (ND) has shown its potential to improve the mechanical and biological properties of such hydrogels. Enhancing the performance properties of natural biopolymer gelatin-based hydrogels can widen their biomedical application possibilities to various areas including drug delivery, tissue engineering and 3D bioprinting.

Method

In this study, natural cross-linker tannic acid (TA) is used along with ferrous sulphate (FS) to optimize the swelling and disintegration of extrudable and 3D printable gelatin hydrogels. The amounts of TA and FS are restricted to improve the extrusion ability of the gels in 3D printing. Further, ND particles (detonation type) are dispersed using twin screw extrusion technology to study their effect on mechanical and biological properties of the 3D printing hydrogel.

Results

The improved dispersion of ND particles helps to improve compressive strength almost ten times and dynamic modulus three times using 40 mg ND (2% w/w of gelatin). The surface-functional groups of detonation ND also contributed for such improvement in mechanical properties due to higher interaction with the hydrogel matrix. The stability of the hydrogels in water was also improved to 7 days. Four times improvement of the cell growth and proliferation was observed in ND based hydrogel.

Conclusion

The cell-supportive nature of these moderately stable and extrudable ND dispersed gelatin hydrogels makes them a good candidate for short term regenerative applications of cell-encapsulated injectable hydrogels with better mechanical properties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00285-3.

Silicon-Vacancy Nanodiamonds as High Performance Near-Infrared Emitters for Live-Cell Dual-Color Imaging and Thermometry

Nanodiamonds (NDs) with color centers are excellent emitters for various bioimaging and quantum biosensing applications. In our work, we explore new applications of NDs with silicon-vacancy centers (SiV) obtained by high-pressure high-temperature (HPHT) synthesis based on metal-catalyst-free growth. They are coated with a polypeptide biopolymer, which is essential for efficient cellular uptake. The unique optical properties of NDs with SiV are their high photostability and narrow emission in the near-infrared region. Our results demonstrate for the first time that NDs with SiV allow live-cell dual-color imaging and intracellular tracking. Also, intracellular thermometry and challenges associated with SiV atomic defects in NDs are investigated and discussed for the first time. NDs with SiV nanoemitters provide new avenues for live-cell bioimaging, diagnostic (SiV as a nanosized thermometer), and theranostic (nanodiamonds as drug carrier) applications.

Silicon-Vacancy Nanodiamonds as High Performance Near-Infrared Emitters for Live-Cell Dual-Color Imaging and Thermometry

Nanodiamonds (NDs) with color centers are excellent emitters for various bioimaging and quantum biosensing applications. In our work, we explore new applications of NDs with silicon-vacancy centers (SiV) obtained by high-pressure high-temperature (HPHT) synthesis based on metal-catalyst-free growth. They are coated with a polypeptide biopolymer, which is essential for efficient cellular uptake. The unique optical properties of NDs with SiV are their high photostability and narrow emission in the near-infrared region. Our results demonstrate for the first time that NDs with SiV allow live-cell dual-color imaging and intracellular tracking. Also, intracellular thermometry and challenges associated with SiV atomic defects in NDs are investigated and discussed for the first time. NDs with SiV nanoemitters provide new avenues for live-cell bioimaging, diagnostic (SiV as a nanosized thermometer), and theranostic (nanodiamonds as drug carrier) applications.

Nanodiamond-based multifunctional platform for oral chemo-photothermal combinational therapy of orthotopic colon cancer

Combination therapy system has become a promising strategy for achieving favorable antitumor efficacy. Herein, a novel oral drug delivery system with colon localization and tumor targeting functions was designed for orthotopic colon cancer chemotherapy and photothermal combinational therapy. The polydopamine coated nanodiamond (PND) was used as the photothermal carrier, through the coupling of sulfhydryl-polyethylene glycol-folate (SH-PEG-FA) on the surface of PND to achieve systematic colon tumor targeting, curcumin (CUR) was loaded as the model drug, and then coated with chitosan (CS) to achieve the long gastrointestinal tract retention and colon localization functions to obtain PND-PEG-FA/CUR@CS nanoparticles. It has high photothermal conversion efficiency and good photothermal stability and exhibited near-infrared (NIR) laser-responsive drug release behavior. Folate (FA) modification effectively promotes the intracellular uptake of nanoparticles by CT26 cells, and the combination of chemotherapy and photothermal therapy (CT/PTT) can enhance cytotoxicity. Compared with free CUR group, nanoparticles prolonged the gastrointestinal tract retention time, accumulated more in colon tumor tissues, and exhibited good photothermal effect in vivo. More importantly, the CT/PTT group exhibited satisfactory tumor growth inhibition effects with good biocompatibility in vivo. In summary, this oral drug delivery system is an efficient platform for chemotherapy and photothermal combinational therapy of orthotopic colon cancer.

SARS-CoV-2 Quantum Sensor Based on Nitrogen-Vacancy Centers in Diamond

The development of highly sensitive and rapid biosensing tools targeted to the highly contagious virus SARS-CoV-2 is critical to tackling the COVID-19 pandemic. Quantum sensors can play an important role because of their superior sensitivity and fast improvements in recent years. Here we propose a molecular transducer designed for nitrogen-vacancy (NV) centers in nanodiamonds, translating the presence of SARS-CoV-2 RNA into an unambiguous magnetic noise signal that can be optically read out. We evaluate the performance of the hybrid sensor, including its sensitivity and false negative rate, and compare it to widespread diagnostic methods. The proposed method is fast and promises to reach a sensitivity down to a few hundreds of RNA copies with false negative rate less than 1%. The proposed hybrid sensor can be further implemented with different solid-state defects and substrates, generalized to diagnose other RNA viruses, and integrated with CRISPR technology.

Prospective environmental risk screening of seven advanced materials based on production volumes and aquatic ecotoxicity

The number and volume of advanced materials being manufactured is increasing. In order to mitigate future impacts from such materials, assessment methods that can provide early indications of potential environmental risk are required. This paper presents a further development and testing of an environmental risk screening method based on two proxy measures: aquatic ecotoxicity and global annual production volumes. In addition to considering current production volumes, this further developed method considers potential future production volumes, thereby enabling prospective environmental risk screening. The proxy measures are applied to seven advanced materials: graphene, graphene oxide, nanocellulose, nanodiamond, quantum dots, nano-sized molybdenum disulfide, and MXenes. Only MXenes show high aquatic ecotoxicity, though the number of test results is still very limited. While current production volumes are relatively modest for most materials, several of the materials (graphene, graphene oxide, nanocellulose, nano-sized molybdenum disulfide, and MXenes) have the potential to become high-volume materials in the future. For MXenes, with both high aquatic ecotoxicity and high potential future production volumes, more detailed environmental risk assessments should be considered. For the other materials with high potential future production volumes, the recommendation is to continuously monitor their aquatic ecotoxicity data. Based on the application of the proxy measures combined with future scenarios for production volumes, we recommend this environmental risk screening method be used in the early development of advanced materials to prioritize which advanced materials should be subject to more detailed environmental assessments.

Pickering emulsions stabilized by carboxylated nanodiamonds over a broad pH range

HYPOTHESIS

Surfactants in emulsions sometimes do not provide adequate stability against coalescence, whereas Pickering emulsions often offer greater stability. In a search for stabilizers offering biocompatibility, we hypothesized that carboxylated nanodiamonds (ND) would impart stability to Pickering emulsions.

EXPERIMENTS

We successfully prepared Pickering emulsions of sunflower oil in water via two different methods: membrane emulsification and probe sonication. The first method was only possible when the pH of the aqueous ND suspension was ≤ 4.

FINDINGS

Pendant-drop tensiometry confirmed that carboxylated ND is adsorbed at the oil/water interface, with a greater decrease in interfacial tension found with increasing ND concentrations in the aqueous phase. The carboxylated ND become more hydrophilic with increasing pH, according to three-phase contact angle analysis, because of deprotonation of the carboxylic acid groups. Membrane emulsification yielded larger (about 30 µm) oil droplets, probe sonication produced smaller (sub-μm) oil droplets. The Pickering emulsions show high stability against mechanical vibration and long-term storage for one year. They remain stable against coalescence across a wide range of pH values. Sonicated emulsions show stability against creaming. In this first-ever systematic study of carboxylated ND-stabilized Pickering emulsions, we demonstrate a promising application in the delivery of β-carotene, as a model active ingredient.

Enhanced osteogenic differentiation of alendronate-conjugated nanodiamonds for potential osteoporosis treatment

Background

Alendronate (Alen) is promising material used for bone-targeted drug delivery due to its high bone affinity and therapeutic effects on bone diseases. In addition, Alen can enhance the osteogenic differentiation of osteoblastic cell. Recently, nanodiamonds (NDs) with hardness, non-toxicity, and excellent biocompatibility are employed as promising materials for carrier systems and osteogenic differentiation. Therefore, we prepared Alen-conjugated NDs (Alen-NDs) and evaluated their osteogenic differentiation performances.

Methods

Alen-NDs were synthesized using DMTMM as a coupling reagent. Morphological change of Mouse calvaria-derived preosteoblast (MC3T3-E1) treated with Alen-NDs was observed using the confocal microscope. The osteogenic differentiation was confirmed by cell proliferation, alkaline phosphatase (ALP), calcium deposition, and real-time polymerase chain reaction assay.

Results

Alen-NDs were prepared to evaluate their effect on the proliferation and differentiation of osteoblastic MC3T3-E1 cells. The Alen-NDs had a size of about 100 nm, and no cytotoxicity at less than 100 μg/mL of concentration. The treatment of NDs and Alen-NDs reduced the proliferation rate of MC3T3-E1 cells without cell death. Confocal microscopy images confirmed that the treatment of NDs and Alen-NDs changed the cellular morphology from a fibroblastic shape to a cuboidal shape. Flow cytometry, alkaline phosphatase (ALP) activity, calcium deposition, and real-time polymerase chain reaction (RT-PCR) confirmed the higher differentiation of MC3T3-E1 cells treated by Alen-NDs, compared to the groups treated by osteogenic medium and NDs. The higher concentration of Alen-ND treated in MC3T3-E1 resulted in a higher differentiation level.

Conclusions

Alen-NDs can be used as potential therapeutic agents for osteoporosis treatment by inducing osteogenic differentiation.

Conjugation with nanodiamonds via hydrazone bond fundamentally alters intracellular distribution and activity of doxorubicin

Doxorubicin (DOX) has been widely incorporated in various delivery forms for tareted treatment of malignant tumors such as triple-negative breast cancer (TNBC), with numerous studies reporting higher therapeutic efficacy and lower toxicity at the same time. However, little attention has been paid to whether DOX in a delivery form acts with the same actions and processes as in free form at the cellular level. This question was investigated in the present study wherein DOX conjugated with polyglycerol-coated nanodiamonds through the pH-sensitive hydrazone bond (Nano-DOX) was compared with DOX in free form on the 4T1 mouse TNBC model. We first found Nano-DOX to have a distinct intracellular distribution profile from DOX. Internalized Nano-DOX mainly stayed in the lysosomes slowly releasing DOX into the cytoplasm and then the nucleus whereas DOX displayed both nuclear and lysosomal distribution after cell uptake. Next, Nano-DOX was shown to induce endoplasmic reticulum (ER) stress without substantial DNA damage while DOX caused massive DNA damage as well as ER stress. Consequently, Nano-DOX only caused minimal activation of pro-inflammatory signaling mediated by MAPK/ERK, NF-κB and STAT3 as seen in response to DOX-inflicted DNA damage. Consistently, DOX-induced activities of ABC transporters, CXCL-1, GM-CSF and IL-6, which are tumor protective events downstream to the pro-inflammatory signaling, were also minimal in Nano-DOX-treated cancer cells. These findings are compelling proof that a chemotherapy in nano form can have distinct intracellular pharmacokinetics from its free from, which can result in altered cellular effects of the drug. Implications of these findings are discussed with an emphasis on nano-drug design, tumor pharmacology and chemoresistance.

UHMWPE / nanodiamond nanocomposites for orthopaedic applications: A novel sandwich configuration based approach

Ultra high molecular weight polyethylene (UHMWPE) remains a primary choice of material for load bearing applications in total joint arthroplasty. Superior mechanical properties and wear resistance are unique to its performance. However, the addition of nanomaterials has improved its properties significantly. In the present study, a novel sandwich configuration has been considered to achieve unique surface and bulk properties specific to these sandwich composites. UHMWPE was reinforced at various loadings of 0.1, 0.3, 0.5, and 0.7 wt. % by surface modified Nano-diamond (ND). It is observed that the young's modulus, yield stress, fracture stress and toughness of UHMWPE were improved by 15, 31, 30, and 49.6% respectively at the optimum loading of 0.5 wt. % ND filler. The % of elongations and impact strength showed best results at 0.3 wt. % ND. Sandwich nanocomposites were prepared with the optimum loading of 0.3 & 0.5 wt. % ND and assessed for their properties and behaviour. The sectional hardness of sandwich nanocomposites revealed the cross-sectional variation of properties of the material. The reasons for diminution of the mechanical properties of nanocomposites and sandwich nanocomposites were also ascertained by rheological studies. The vibration response, damping behaviour, water contact angle and density of the composites which influence the longevity of the implant material were also assessed. The sandwich composite (PE 0.3ND - PE - PE 0.3ND) has shown better performance in all respect as compare to SW1 and SW3 composite due to good intermingling between the adjacent layers. It is concluded that the existence of ND improved the surface properties and mechanical properties of UHMWPE. However, sandwich nanocomposites have shown better properties unique unto itself.

Hand-ground fullerene-nanodiamond composite for photosensitized water treatment and photodynamic cancer therapy

The unique capability of fullerene (C₆₀) to absorb light and generate reactive oxygen species (ROS) has been extensively studied for photosensitized water treatment and cancer therapy. Various material synthesis strategies have been proposed in parallel to overcome its intrinsic hydrophobicity and to enhance availability in water and physiological media. We present here a strikingly simple approach to make C₆₀ available to these applications by hand-grinding dry C₆₀ powder with nanodiamond (ND) using a mortar and pestle. The resulting ND-C₆₀ composite was found to form a stable aqueous colloidal suspension and efficiently drive photosensitized production of ROS under visible light illumination. ND-C₆₀ rapidly adsorbed and oxidized organic contaminants by photogenerated ROS. In the experiments for photodynamic cancer therapy, ND-C₆₀ was internalized by cancer cells and induced cell apoptosis without noticeable toxicity. Treatment of tumor-bearing mice with ND-C₆₀ and light irradiation resulted in tumor shrinkage and prolonged survival time.

Examining relaxivities in suspensions of nanodiamonds grafted by magnetic entities: comparison of two approaches

OBJECTIVES

Detonation nanodiamonds (DND) with Gd³⁺ ions directly grafted to the DND surface have recently demonstrated enhanced relaxivity for protons in aqueous suspensions. Herewith, the relaxivity measurements were done on a series of suspensions with the gadolinium content varied by changing number of Gd³⁺ ions grafted per each DND particle whereas the DND content in each suspension was kept the same. Such an approach to vary the contrast agent content differs from that commonly used in the relaxivity measurements. In the common approach, contrast agents are directly dissolved/suspended in media. Aiming to test validity of the unconventional approach, in the present study we follow the common way of measurement relaxivity: using variable concentrations of carriers (DND particles) in aqueous suspension keeping the number of Gd³⁺ ions per each carrier fixed.

MATERIALS AND METHODS

¹H NMR relaxation measurements of aqueous suspensions of DND with Gd³⁺ ions directly grafted to the DND surface were carried out at room temperature (293 K or 20 °C) in the external magnetic field B₀ = 8.0 T.

RESULTS AND CONCLUSIONS

Comparative study of two approaches for measuring relaxivity in suspensions containing DND as magnetic entities' carriers reveals complete identity of techniques in use.

A review of recent advances in nanodiamond-mediated drug delivery in cancer

INTRODUCTION

Nanodiamond (ND) refers to diamond particles with sizes from few to near 100 nanometers. For its superb physical, chemical and spectroscopic properties, it has been proposed and studied with the aims for bio imaging and drug delivery. Many modalities on conjugating drug molecules on ND to form ND-X for more efficient drug delivery have been demonstrated in the cellular and animal models.

AREA COVERED

Many novel drug delivery approaches utilizing nanodiamond as a platform have been demonstrated recently. This review summarizes recent developments on the nanodiamond facilitated drug delivery, from the ND-X complexes preparations to tests in the cellular and animal models. The outlook on clinical translation is discussed.

EXPERT OPINION

Nanodiamond and drug complexes (ND-X) produced from different methods are realized for drug delivery; almost all studies reported ND-X being more efficient compared to pure drug alone. However, ND of particle size less than 10 nm are found more toxic due to size and surface structure, and strongly aggregate. In vivo studies demonstrate ND accumulation in animal organs and no confirmed long-term effect studies on their release from organs are available. Standardized nanodiamond materials and drug delivery approaches are needed to advance the applications to the clinical level.

Highly biocompatible multifunctional hybrid nanoparticles based on Fe3O4 decorated nanodiamond with superior superparamagnetic behaviors and photoluminescent properties

The multifunctional nanostructures with superparamagnetic and luminescent properties undergo revolution in the field of bio-nanotechnology. In this article, we reported a facile and efficient one-step modified co-precipitation method to load superparamagnetic Fe₃O₄ nanoparticle on oxidized nanodiamond (Ox-ND). Subsequently, the as-prepared Ox-ND/Fe₃O₄ hybrid nanoparticle was surface functionalized with vinyltrimethoxysilane (VTMS) to enhance its compatibility with organic media. The structure, morphology, magnetic, and optical properties of the nanohybrid were systematically investigated. The results confirmed successful loading of crystalline Fe₃O₄ on the surface of Ox-ND. Ox-ND/Fe₃O₄ multifunctional hybrid nanoparticle presented strong superparamagnetism (with a saturation magnetization of 67 emu/g at room temperature) and photoluminescence (blue emission) with good chemical reactivity. PrestoBlue assay indicated great biocompatibility of silanized Ox-ND/Fe₃O₄ in MCF-7 cells even at high concentrations, e.g. 7.2 mg/mL. The hybrid nanoparticle synthesized in this study potentially opens doors for high contrast imaging and targeted delivery applications.

The sp3/sp2 carbon ratio as a modulator of in vivo and in vitro toxicity of the chemically purified detonation-synthesized nanodiamond via the reactive oxygen species generation

Nanodiamonds have been suggested as biocompatible materials and are suitable for various biomedical applications, but little is known about how to synthesize safer nanodiamonds. Herein, seven different detonation-synthesized nanodiamonds (DNDs) with sequential sp³/sp² carbon ratios were assembled by controlling the chemical purification parameters and the role of sp³/sp² carbon ratio on the toxicity of DNDs was investigated. Carbon black and nickel oxide nanoparticles were used as reference particles. The intrinsic reactive oxygen species (ROS) generation potential of DNDs was estimated by a 2'7'-dichlorofluorescein diacetate (DCFH-DA) assay, and these values showed a good negative correlation with the sp³/sp² carbon ratios, which implies that ROS generation increased as the sp³/sp² carbon ratio decreased. As a model to investigate inflammogenic potential of DND samples, a rat intratracheal instillation model was used as the lung is very sensitive to nanoparticle exposures. The sp³/sp² carbon ratios or the estimated values of ROS generation potential showed excellent linear correlations with the number of neutrophils and pro-inflammatory cytokines in bronchoalveolar lavage fluid at 24 h after instillation. Treatment of DND samples to THP-1 derived macrophages also showed that the sp³/sp² carbon ratios or the estimated values of ROS generation potential were closely related with the toxicity endpoints such as cell viability and pro-inflammatory cytokines. Taken together, these data demonstrate that the sp³/sp² carbon ratio is the key determinant for the toxicity of DNDs, which can be a useful tool for the safer-by-design approach of DNDs and the safety assessment of carbon nanoparticles.

Carbon nanomaterial-derived lung burden analysis using UV-Vis spectrophotometry and proteinase K digestion

BACKGROUND

The quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics. However, some types of nanomaterials, including carbon nanomaterials (CNMs), are difficult to quantify in a biological matrix. Therefore, developing improved methodologies for quantification of CNMs in vital organs is instrumental in their continued modification and application.

RESULTS

In this study, carbon black, nanodiamond, multi-walled carbon nanotube, carbon nanofiber, and graphene nanoplatelet were assembled and used as a panel of CNMs. All CNMs showed significant absorbance at 750 nm, while their bio-components showed minimal absorbance at this wavelength. Quantification of CNMs using their absorbance at 750 nm was shown to have more than 94% accuracy in all of the studied materials. Incubating proteinase K (PK) for 2 days with a mixture of lung tissue homogenates and CNMs showed an average recovery rate over 90%. The utility of this method was confirmed in a murine pharyngeal aspiration model using CNMs at 30 μg/mouse.

CONCLUSIONS

We developed an improved lung burden assay for CNMs with an accuracy > 94% and a recovery rate > 90% using PK digestion and UV-Vis spectrophotometry. This method can be applied to any nanomaterial with sufficient absorbance in the near-infrared band and can differentiate nanomaterials from elements in the body, as well as the soluble fraction of the nanomaterial. Furthermore, a combination of PK digestion and other instrumental analysis specific to the nanomaterial can be applied to organ burden analysis.

Carbon nanostructures: The drug and the delivery system for brain disorders

Neurodegenerative disorders and brain tumors are major pathological conditions affecting the brain. The delivery of therapeutic agents into the brain is not as easy as to other organs or systems. The presence of the blood-brain barrier (BBB) makes the drug delivery into the brain more complicated and challenging. Many techniques have been developed to overcome the difficulties with BBB and to achieve brain-targeted drug delivery. Incorporation of the drugs into nanocarriers capable to penetrate BBB is a simple technique. Different nanocarriers have been developed including polymeric nanoparticles, carbon nanoparticles, lipid-based nanoparticles, etc. Carbon nanostructures could make a superior position among them, because of their good biocompatibility and easy penetration of BBB. Carbon-family nanomaterials consist of different carbon-based structures including zero-dimensional fullerene, one-dimensional carbon nanotube, two-dimensional graphene, and some other related structures like carbon dots and nanodiamonds. They can be used as efficient carriers for drug delivery into the brain. Apart from the drug delivery applications, they can also be used as a central nervous system (CNS) therapeutic agent; some of the carbon nanostructures have neuroregenerative activity. Their influence on neuronal growth and anti-amyloid action is also interesting. This review focuses on different carbon nanostructures for brain-targeted drug delivery and their CNS activities. As a carrier and CNS therapeutic agent, carbon nanostructures can revolutionize the treatment of brain disorders.

Changes in tribological and antibacterial properties of poly(methyl methacrylate)-based 3D-printed intra-oral appliances by incorporating nanodiamonds

It is essential for 3D-printed intra-oral appliances to be able to withstand the mechanical and microbial insult existent in the harsh environment of the oral cavity. Poly(methyl methacrylate) (PMMA)-based appliances are widely used in dentistry. Hence, the present study aimed to evaluate the role of nanodiamonds (NDs) as fillers to enhance the resistance to friction and wear. Using a solution-based mixing technique, 0.1 wt% ND was incorporated into the PMMA, and specimens were 3D-printed for tribological and bacterial analysis. The control specimens without ND fillers were tested against specimens with both amine-functionalized NDs (A-ND) and pure non-functionalized NDs (ND). The surface hardness test revealed a statistically significant increase in the Vickers micro-hardness (p < 0.001) in the nanocomposite groups. There was a significant reduction in the coefficient of friction (COF) (p < 0.01) in both the ND and A-ND nanocomposites compared to the stainless steel (SS) counter surfaces. However, for titanium (Ti)-based specimens, the COF of the control group was similar to that of A-ND but lower than that of ND. The wear resistance evaluation revealed that both the ND and A-ND groups displayed enhanced resistance to surface loss in comparison to the controls for both SS and Ti counter-surfaces (p < 0.001). Furthermore, both A-ND and ND exhibited significantly enhanced resistance to the formation of Streptococcus mutans biofilms after 48 h (p < 0.01) compared to the control group. Hence, we concluded that the addition of 0.1 wt% ND in the PMMA-based resin for 3D printing resulted in significant improvement in properties such as COF, wear resistance, and resistance to S. mutans, without any notable impact associated with the functionalization of the NDs.

An amperometric biosensor based on poly(L-aspartic acid), nanodiamond particles, carbon nanofiber, and ascorbate oxidase-modified glassy carbon electrode for the determination of L-ascorbic acid

An amperometric L-ascorbic acid biosensor utilizing ascorbate oxidase (AOx) immobilized onto poly(L-aspartic acid) (P(L-Asp)) film was fabricated on carbon nanofiber (CNF) and nanodiamond particle (ND)-modified glassy carbon electrode (GCE). Effects of AOx, ND, and CNF amounts were investigated by monitoring the response currents of the biosensor at different amounts of AOx, ND, and CNF. The electropolymerization step of L-aspartic acid on CNF-ND/GCE surface was also optimized. Scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques were used to enlighten the modification steps of the biosensor. The effects of pH and applied potential were studied in detail to achieve the best analytical performance. Under optimized experimental conditions, the AOx/P(L-Asp)/ND-CNF/GCE biosensor showed a linear response to L-ascorbic acid in the range of 2.0 × 10^-7-1.8 × 10^-3 M with a detection limit of 1.0 × 10^-7 M and sensitivity of 105.0 μAmM^-1 cm^-2. The novel biosensing platform showed good reproducibility and selectivity. The strong interaction between AOx and the P(L-Asp)/ND-CNF matrix was revealed by the high repeatability (3.4%) and good operational stability. The AOx/P(L-Asp)/ND-CNF/GCE biosensor was successfully applied to the determination of L-ascorbic acid in vitamin C effervescent tablet and pharmaceutical powder containing ascorbic acid with good results, which makes it a promising approach for quantification of L-ascorbic acid. Graphical abstract.

Chitosan-coated nanodiamonds: Mucoadhesive platform for intravesical delivery of doxorubicin

Nanodiamonds (NDs) are an emerging delivery system with a massive surface area qualifying them for efficient loading with various drugs. However, NDs easily scavenge ions upon mixing with physiological media leading to rapid aggregation. Herein, chitosan was employed to endue steric stabilization to NDs and confer adhesiveness to the particles improving their retention in the urinary bladder. The effect of chitosan molecular weight and pH on the particle size and surface charge of chitosan-coated doxorubicin-loaded NDs (Chi-NDX) was investigated. Selected formula exhibited high drug loading efficiency (>90 %), small particle size (<150 nm), good colloidal stability, acid-favored drug release but limited stability in cell culture media. After further stabilization with TPP or dextran sulfate, selected TPP-treated formula displayed more potent cytotoxic effect compared with free doxorubicin and uncoated nanoparticles, and higher drug retention in ex vivo bovine bladder. Therefore, TPP-Chi-NDX is suggested as a promising system for mucosal anticancer delivery.

Ultrafast and simultaneous removal of anionic and cationic dyes by nanodiamond/UiO-66 hybrid nanocomposite

In this research, UiO-66 and its composite nanoparticles with thermally oxidized nanodiamond (OND) were synthesized via a simple solvothermal method and utilized as solid adsorbent for the removal of anionic methyl red (MR) dye and cationic malachite green (MG) dye from contaminated water. The synthesized adsorbents were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), N₂ adsorption-desorption, and zeta potential analyzer. The influences of various factors such as initial concentrations of the dyes, adsorption process time, solution pH, solution temperature and ionic strength on adsorption behavior of MR dye onto OND-UiO hybrid nanoparticle were investigated. The adsorption of MR onto OND-UiO hybrid nanoparticle could be well described by Langmuir isotherm model. Meanwhile, pseudo-second order kinetic model was found to be suitable for illustration of adsorption kinetics of MR onto OND-UiO. Thermodynamic investigation suggested that the adsorption process was spontaneous and endothermic, and controlled by an entropy change instead of enthalpy effect. The experimental adsorption results indicated that OND-UiO hybrid nanoparticle could simultaneously adsorb 59% of MR and 43% of MG from the mixture of both dyes in only 2 min showing synergistic effect compared with single UiO-66 and OND nanoparticles in terms of adsorption rate and removal capacity of anionic dyes. The appropriate removal efficiency, rapid adsorption kinetic, high water stability, and good reusability make OND-UiO hybrid nanoparticle attractive candidate for simultaneously removal of both anionic MR and cationic MG dyes from wastewater.

Location of paramagnetic defects in detonation nanodiamond from proton spin-lattice relaxation data

We developed an approach for determining location of intrinsic paramagnetic defects in nanodiamonds from the data of proton spin-lattice relaxation of the surface hydrogen atoms. The approach was applied to the detonation nanodiamond (DND) of the diameter of 5 nm. We found that dangling bonds with unpaired electron spins are located within the near-surface belt at the distance of 0.3-0.9 nm from the DND surface. The NMR data are compared with the results of EPR measurements.

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.

Effect of Nanodiamond Surface Chemistry on Adsorption and Release of Tiopronin

Tiopronin is an FDA-approved thiol drug currently used to treat cystinuria and rheumatoid arthritis. However, due to its antioxidant properties, it may be beneficial in a variety of other conditions. One primary obstacle to its wider application is its limited bioavailability, which necessitates administration of high systemic doses to achieve localized therapeutic effects. Incorporation of a drug delivery vehicle can solve this dilemma by providing a means of controlled, targeted release. Functionalized nanodiamond is a promising theranostic platform that has demonstrated great potential for biomedical applications, including drug delivery. Design of nanodiamond theranostic platforms requires comprehensive understanding of drug-platform interactions, and the necessary physical chemical investigations have only been realized for a limited number of compounds. Towards the long-term goal of developing a nanodiamond-tiopronin treatment paradigm, this study aims to shed light on the effects of nanodiamond surface chemistry on adsorption and release of tiopronin. Specifically, adsorption isotherms were measured and fit to Langmuir and Freundlich models for carboxylated, hydroxylated, and aminated nanodiamonds, and release was monitored in solutions at pH 4.0, 5.8, 7.3, and 8.1. Our results indicate that aminated nanodiamonds exhibit the highest loading capacity while hydroxylated nanodiamonds are the most effective for sustained release. Therefore, a high degree of flexibility may be afforded by the use of nanodiamonds with different surface chemistries optimized for specific applications.

Spontaneous Complexation of Fullerene Aggregates on Nanodiamond Aggregates and Their Enhanced Photocurrent Generation

Supramolecular composites composed of fullerene C₆₀ and carbon nanodiamond (ND) were constructed through spontaneous complexation of C₆₀ aggregates onto the surface of ND aggregates in N-methylpyrrolidone (NMP). The resulting C₆₀ -ND composite was assembled onto a nanostructured SnO₂ electrode by an electrophoretic deposition method. Formation of the C₆₀ -ND composite was confirmed by dynamic light scattering (DLS) and field-emission scanning electron microscopy (FESEM). The C₆₀ -ND composite on the SnO₂ electrode showed high incident photon-to-current efficiencies (IPCEs) in the visible region as compared with the single component system of C₆₀ or ND. The improved photocurrent generation of the C₆₀ -ND composite may result from the photoinduced charge separation at the interface between C₆₀ and ND. These results obtained here will provide valuable information on the design of optoelectronic devices based on all-nanocarbon materials.

Biological impact of nanodiamond particles - label free, high-resolution methods for nanotoxicity assessment

Current methods for the assessment of nanoparticle safety that are based on 2D cell culture models and fluorescence-based assays show limited sensitivity and they lack biomimicry. Consequently, the health risks associated with the use of many nanoparticles have not yet been established. There is a need to develop in vitro models that mimic physiology more accurately and enable high throughput assessment. There is also a need to set up new assays that offer high sensitivity and are label-free. Here we developed 'mini-liver' models using scaffold-free bioprinting and used these models together with label-free nanoscale techniques for the assessment of toxicity of nanodiamond produced by laser-assisted technology. Results showed that NDs induced cytotoxicity in a concentration and exposure-time dependent manner. The loss of cell function was confirmed by increased cell stiffness, decreased cell membrane barrier integrity and reduced cells mobility. We further showed that NDs elevated the production of reactive oxygen species and reduced cell viability. Our approach that combined mini-liver models with label-free high-resolution techniques showed improved sensitivity in toxicity assessment. Notably, this approach allowed for label-free semi-high throughput measurements of nanoparticle-cell interactions, thus could be considered as a complementary approach to currently used methods.

Formulation and characterization of a novel PHBV nanocomposite for bone defect filling and infection treatment

Biodegradable materials that combine bioactivity with sustained drug release have been proved promising for the treatment and prophylaxis of bone infection. In this work, injection-molded nanocomposites were formulated from poly(3-hydroxybutyrate-co-3-6%hydroxyvalerate) (PHBV), nanodiamond (nD) and nanohydroxyapatite (nHA) loaded with vancomycin (VC). The components were compounded using a rotary evaporator (PHBV/nHA/VC/nD-R) or a spray-dryer (PHBV/nHA/VC/nD-SD). The nanoparticles acted as a nucleating agent, increasing PHBV crystallinity from 57.1% to up to 73.3% (PHBV/nHA/VC/nD-SD). The nHA particles were found to be well distributed on the formulations fracture surface observed by SEM-EDS micrographs. PHBV/nHA/VC/nD-SD presented higher glass transition temperature (18.1 vs 14.8 °C) and stronger interface than PHBV/nHA/VC/nD-R, as determined by dynamic mechanical analysis (DMA). Furthermore, the incorporation of nanoparticles increased PHBV flexural elastic modulus by 34% and match the reported for human bone. Both systems were able to present a sustained release of VC for 22 days, reaching 7.1 ± 1.3%(PHBV/nHA/VC/nD-R) and 4.8 ± 0.6% (PHBV/nHA/VC/nD-SD). VC presented antibacterial activity even after being processed at 178 °C in an injection molding machine. Moreover, in vitro assays showed a good adhesion and growth of cells on the specimens and suggested a non-cytotoxic and non-cytostatic behavior. These findings indicate that these systems can be further explored as bone defect filling material.

Polymer/nanodiamond composites - a comprehensive review from synthesis and fabrication to properties and applications

Nanodiamond (ND) is an allotrope of carbon nanomaterials which exhibits many outstanding physical, mechanical, thermal, optical and biocompatibility characteristics. Meanwhile, ND particles possess unique spherical shape containing diamond-like structure at the core with graphitic carbon outer shell which intuitively contains many oxygen-containing functional groups at the outer surface. Such superior properties and unique structural morphology of NDs are essentially attractive to develop polymer composites with multifunctional properties. However, despite a long history from the discovery of NDs, which is dated back to the1960s, this nanoparticle has been less explored in the field of polymer (nano)composites compared with other carbon nanomaterials, e.g. carbon nanotube (CNT) and graphene. However, open literature indicates that research works in the field of polymer/ND (PND) composites have gained great momentum in the past half a decade. The present article provides a comprehensive review on recent achievements in ND based polymer composites. This review covers a very broad aspect from the synthesis, purification and functionalization of NDs to dispersion, preparation and fabrication of polymer/ND (PND) composites with a look in their recent applications for both structural and functional basis. Therefore, the review would be useful to pave the way for researchers to take some advancing steps in this respect.

Colloids of detonation nanodiamond particles for advanced applications

Nanodiamond (ND) is one of the most attractive allotropic modification of carbon due to their unique physical and chemical properties. In the present review the current state of science and technology in the field of NDs is analyzed. ND can be used in various application and in different form e.g. as a dispersion phase in suspension, as a filler in composites, etc., so the sedimentation stability of ND in different media are under scrutiny. Thus, theoretical aspects of ND suspension coagulation mechanisms and the methods avoiding it were considered. The dependence of rheological behavior on particles modification was discussed as well. Various methods for the preparation and modification of NDs to obtain particles of various sizes on a nanometer scale with different physicochemical properties were reviewed. The area of practical application for NDs was considered on the example of polymer composites. The various manufacturing methods, mechanical properties and medical aspects for thermosetting, thermoplastic and elastomer ND composites were summarized.

Doxorubicin-polyglycerol-nanodiamond composites stimulate glioblastoma cell immunogenicity through activation of autophagy

Immunosuppression is a salient feature of GBM associated with the disease's grim prognosis and the limited success of anti-GBM immunotherapy. Stimulating immunogenicity of the GBM cells (GC) is a promising approach to subverting the GBM-associated immunosuppression. We had previously devised a drug composite based on polyglycerol-functionalized nanodiamonds bearing doxorubicin (Nano-DOX) and demonstrated that Nano-DOX effectively modulated GBM's immunosuppressive microenvironment through stimulating the immunogenicity of GC and initiated anti-GBM immune responses. The present study now explored the mechanism of Nano-DOX's immunostimulatory action. Nano-DOX was found to induce autophagy rather than apoptosis in GC and stimulated GC to emit antigens and damage-associated molecular patterns (DAMPs) that are potent adjuvants, which resulted in enhanced activation of dendritic cells (DC). Heightened autophagosome release was observed in Nano-DOX-treated GC but was shown not to be a major channel of antigen donation. Blocking autophagy in GC not only reduced Nano-DOX-stimulated GC antigen donation and DAMPs emission, but also efficiently attenuated DC activation stimulated by Nano-DOX-treated GC. Taken together, these findings suggest that activation of autophagy is a central mechanism whereby Nano-DOX stimulates GC's immunogenicity. Our work provides new insight on how nanotechnology can be applied to therapeutically modulate the GBM immune microenvironment by harnessing autophagy in the cancer cells. STATEMENT OF SIGNIFICANCE: Immunosuppression is a salient feature of GBM associated with the grim prognosis of the disease and the limited success of anti-GBM immunotherapy. We demonstrated that Doxorubicin-polyglycerol-nanodiamond composites could activate autophagy in GBM cells and thereby stimulate the immunogenecity of GBM cells. This discovery 1, sheds new light on how nanotechnology could be applied to therapeutically modulate the tumor immune microenvironment, and 2, provides a powerful tool for subverting the GBM's immunosuppressive microenvironment, which has great therapeutic potential for the treatment of GBM.

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.

Immobilization of horseradish peroxidase on PMMA nanofibers incorporated with nanodiamond

In the present study, nanodiamond (ND) was blended with polymethyl methacrylate (PMMA) and then electrospun into nanofibers (nfPMMA-ND) for the immobilization of horseradish peroxidase (HRP). The maximum immobilization efficiency of HRP (96%) was detected at 10% ND and pH 7.0. ATR-FTIR, SEM and TEM were used to characterize the immobilized enzyme. The immobilized enzyme retained 60% of its initial activity after ten reuses. The pH was shifted from 7.0 for soluble HRP to 7.5 for the immobilized enzyme. The soluble HRP had an optimum temperature of 30 °C, whereas this temperature was shifted to 40 °C for the immobilized enzyme. The substrate analogs were oxidized by immobilized HRP with higher efficiencies than those of soluble HRP. The kinetic results showed that the soluble HRP had more affinity toward guiacol and H₂O₂ than immobilized HRP. The effect of metal ions on soluble and immobilized HRP was studied. The immobilized HRP was markedly more stable when it exposed to urea, isopropanol, butanol and heptane compared with the soluble enzyme. The immobilized HRP exhibited high resistance to proteolysis by trypsin than that of soluble enzyme. In conclusion, the nfPMMA-ND-HRP could be employed in several applications such as biosensor, biomedical and bioremediation.

Motion Control and Optical Interrogation of a Levitating Single Nitrogen Vacancy in Vacuum

Levitation optomechanics exploits the unique mechanical properties of trapped nano-objects in vacuum to address some of the limitations of clamped nanomechanical resonators. In particular, its performance is foreseen to contribute to a better understanding of quantum decoherence at the mesoscopic scale as well as to lead to novel ultrasensitive sensing schemes. While most efforts have focused so far on the optical trapping of low-absorption silica particles, further opportunities arise from levitating objects with internal degrees of freedom, such as color centers. Nevertheless, inefficient heat dissipation at low pressures poses a challenge because most nano-objects, even with low-absorption materials, experience photodamage in an optical trap. Here, by using a Paul trap, we demonstrate levitation in vacuum and center-of-mass feedback cooling of a nanodiamond hosting a single nitrogen-vacancy center. The achieved level of motion control enables us to optically interrogate and characterize the emitter response. The developed platform is applicable to a wide range of other nano-objects and represents a promising step toward coupling internal and external degrees of freedom.

Fabrication and optimization of Nanodiamonds-composited poly(ε-caprolactone) fibrous matrices for potential regeneration of hard tissues

Background

Electrospun fibrous matrices are of great importance for tissue engineering and drug delivery device. However, relatively low mechanical strength of the fibrous matrix is one of the major disadvantages. NDs with a positive charge were selected to enhance the mechanical property of a composited fibrous matrix by inducing the intermolecular interaction between NDs and polymer chain. We prepared ND-composited poly (ε-caprolactone) (PCL) fibrous matrices by electrospinning and evaluated their performance in terms of mechanical strength and cell behaviors.

Methods

A predetermined amounts of NDs (0.5, 1, 2 and 3 wt%) were added into PCL solution in a mixture of chloroform and 2,2,2-trifluoroethanol (8:2). ND-composited PCL (ND/PCL) fibrous matrices were prepared by electrospinning method. The tensile properties of the ND/PCL fibrous matrices were analyzed by using a universal testing machine. Mouse calvaria-derived preosteoblast (MC3T3-E1) was used for cell proliferation, alkaline phosphatase (ALP) assay, and Alizarin Red S staining.

Results

The diameters of the fibrous matrices were adjusted to approximately 1.8 μm by changing process variables. The intermolecular interaction between NDs and PCL polymers resulted in the increased tensile strength and the favorable interfacial adhesion in the ND/PCL fibrous matrices. The ND/PCL fibrous matrix with 1 wt% of ND had the highest tensile strength among the samples and also improved proliferation and differentiation of MC3T3-E1 cells.

Conclusions

Compared to the other samples, the ND/PCL fibrous matrix with 1 wt% of ND concentration exhibited superior performances for MC3T3 cells. The ND/PCL fibrous matrix can be potentially used for bone and dental tissue engineering.

Direct detection of carbapenemase-associated proteins of Acinetobacter baumannii using nanodiamonds coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The appearance and spread of carbapenem-resistant Acinetobacter baumannii (CRAB) pose a challenge for optimization of antibiotic therapies and outbreak preventions. The carbapenemase production can be detected through culture-based methods (e.g. Modified Hodge Test-MHT) and DNA based methods (e.g. Polymerase Chain Reaction-PCR). The culture-based methods are time-consuming, whereas those of PCR assays need only a few hours but due to its specificity, can only detect known genetic targets encoding carbapenem-resistance genes. Therefore, new approaches to detect carbapenemase-producing A. baumannii are of great importance. Here, we have developed a rapid and novel method using detonation nanodiamonds (DNDs) as a platform for concentration and extraction of A. baumannii carbapenemase-associated proteins prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS) analysis. To concentrate and extract the A. baumannii carbapenemase-associated proteins, we tested several protein precipitation conditions and found a 0.5% trifluoroacetic acid (TFA) solution within the bacterial suspension could result in strong ion signals with DNDs. A total of 66 A. baumannii clinical-isolates including 51 carbapenem-resistant strains and 15 carbapenem-susceptible strains were tested. Our result showed that among the 51 carbapenem-resistant strains 49 strains had a signal at m/z ~40,279 (±87); among the 15 carbapenem-susceptible strains, 4 strains showed a signal at m/z ~40,279. With on-diamond digestion, we confirmed that the captured protein at m/z ~40,279 was related to ADC family extended-spectrum class C beta-lactamase, from A. baumannii. Using this ADC family protein as a biomarker (m/z ~ 40,279) for carbapenem susceptibility testing of A. baumannii, the sensitivity and the specificity could reach 96% and 73% as compared to traditional imipenem susceptibility testing (MIC results). However, the sensitivity and specificity of this method reached 100% as compared to polymerase chain reaction (PCR) result. Our approach could directly detect the carbapenemase-associated proteins of A. baumannii within 90 min and does not require addition of carbapenemase substrate which is required in the MHT or other mass spectrometric methods. For future applications, our method could be efficiently used in the detection of other carbapenemase-producing bacteria.

Raman Spectra and Bulk Modulus of Nanodiamond in a Size Interval of 2-5 nm

Nanodiamond in a 2-5-nm size interval (which is typical for an appearance of quantum confinement effect) show Raman spectra composed of 3 bands at 1325, 1600, and 1500 cm^-1 (at the 458-nm laser excitation) which shifts to 1630 cm^-1 at the 257-nm laser excitation. Contrary to sp²-bonded carbon, relative intensities of the bands do not depend on the 458- and 257-nm excitation wavelengths, and a halfwidth and the intensity of the 1600 cm^-1 band does not change visibly under pressure at least up to 50 GPa. Bulk modulus of the 2-5-nm nanodiamond determined from the high-pressure study is around 560 GPa. Studied 2-5-nm nanodiamond was purified from contamination layers and dispersed in Si or NaCl.

Nanodiamond enhances immune responses in mice against recombinant HA/H7N9 protein

Background

The continuing spread of the newly emerged H7N9 virus among poultry in China, as well as the possibility of human-to-human transmission, has attracted numerous efforts to develop an effective vaccine against H7N9. The use of nanoparticles in vaccinology is inspired by the fact that most pathogens have a dimension within the nano-size range and therefore can be processed efficiently by the immune system, which leads to a potent immune response. Herein, we report a facile approach to increase antigen size to achieve not only fast but also effective responses against the recombinant HA/H7N9 protein via a simple conjugation of the protein onto the surface of nanodiamond particles.

Results

In this study, trimeric Haemagglutinin (H7) that is transiently expressed in N. benthamiana was purified using affinity chromatography, and its trimeric state was revealed successfully by the cross-linking reaction. The trimeric H7 solution was subsequently mixed with a nanodiamond suspension in different ratios. The successful conjugation of the trimeric H7 onto the surface of nanodiamond particles was demonstrated by the changes in size and Zeta-potential of the particles before and after protein coating, Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and Western-blot analysis. Next, biofunction of the protein-nanodiamond conjugates was screened using a haemagglutination assay. A mixture containing 5 µg of trimeric H7 and 60 µg of nanodiamond corresponds to a ratio of 1:12 (w/w) of agglutinated chicken red blood cells at HA titer of 1024, which is 512-fold higher than the HA titer of free trimeric H7. After the 2nd and 3rd immunization in mice, ELISA and Western blot analyses demonstrated that the physical mixture of trimeric H7 protein and nanodiamond (1:12, w/w) elicited statistically significant stronger H7-specific-IgG response demonstrated by higher amounts of H7N9-specific IgG (over 15.4-fold with P < 0.05 after the second immunization).

Conclusions

These results indicated a potential effect inherent to nanodiamond towards modulating immune systems, which should be further evaluated and broadly applied in nanovaccine development.

Functionalization of Nanodiamond with Four Kinds of Expoxies

In this work, a simple and effective method for the covalent functionalization of nanodiamond (ND) with four epoxies has been developed. After homogenization by mixed acids and thionyl chlorides, the surface of ND was modified with triethylenetetramine (TETA) to possess amine groups, which were used as active points to react with epoxy by ring opening reaction. Four different epoxies used are bifunctional diglycidyl ether of bisphenol-A (DGEBA), trifunctional triglycidyl p-amino phenol (TGAP), tetrafunctional tetraglycidyldiamino diphenylmethane (TGDDM) and bisphenol-A novolac epoxy resin (BAEPN). FT-IR spectra revealed that the epoxy was covalently attached to the ND (ND-g-epoxy). In addition, functionalized ND particles were characterized with WAXD and UV-Vis spectra to confirm the result. The weight gains as a result of the epoxy-functionalized ND were determined by TGA analysis. The ND-g-epoxy particles were better dispersed in common organic solvents and the average diameters were characterized. The better dispersion and of the modified ND were identified from the SEM images.

Plant Cell Imaging Based on Nanodiamonds with Excitation-Dependent Fluorescence

Despite extensive work on fluorescence behavior stemming from color centers of diamond, reports on the excitation-dependent fluorescence of nanodiamonds (NDs) with a large-scale redshift from 400 to 620 nm under different excitation wavelengths are so far much fewer, especially in biological applications. The fluorescence can be attributed to the combined effects of the fraction of sp(2)-hybridized carbon atoms among the surface of the fine diamond nanoparticles and the defect energy trapping states on the surface of the diamond. The excitation-dependent fluorescent NDs have been applied in plant cell imaging for the first time. The results reported in this paper may provide a promising route to multiple-color bioimaging using NDs.