Thiourea modification of fluorescent nanodiamonds towards enhanced quantum sensing

Fluorescent HPHT nanodiamonds have disk- and rod-like shapes

Fluorescent nanodiamonds (FNDs) with nitrogen vacancy centers (NVCs) show promise for use as thermometers owing to their unique physicochemical and optical properties. FND-based thermometry has been steadily developing and is now transitioning into the practical application phase. Various approaches have been proposed for FND assembly, which is a key process for temperature mapping applications. However, the assembly of high-sensitivity FND thermometers remains challenging because it requires the fabrication of three-dimensionally aggregated FNDs across the target area to generate a strong fluorescence signal. To overcome this drawback, we aimed to enable the microfluidics-guided assembly of FNDs to enhance the sensitivity of FND-based thermometry. Specifically, a microfluidic template with through-holes was used to fabricate vertically aggregated FNDs (FND clusters) on a substrate, thereby improving the signal-to-noise ratio (SNR) by superimposing the individual fluorescence events of the FNDs. The FND clusters were arrayed over a millimeter-scale area, and sensitivity improvements were achieved through vertical aggregation. Furthermore, the fluorescence spectra of the FND clusters were investigated to test the increase in temperature-mapping accuracy. Our microfluidics-guided assembly method has potential as a practical approach for creating an array of high-sensitivity FND thermometers on scalable substrates, broadening their use in various fields such as chemistry, electronics, and biology. • A novel microfluidic method vertically assembles fluorescent nanodiamonds (FNDs). • 10 µm diameter FND clusters were arrayed at 20 µm pitch over a millimeter-scale area. • High signal-to-noise ratio (SNR) of the fluorescence achieved by vertical aggregation. • Vertical aggregation of FNDs was found to provide improved accuracy for temperature mapping. • Provision of a practical approach for the fabrication of sensitive FND thermometers.

Quantum sensors based on fluorescent nanodiamonds (FNDs) have emerged as potential nanosensors for measuring the physical parameters inside single cells due to their remarkable photostability and unique magneto-optical properties. Owing to the physicochemical inertness of FNDs, they can be hybridized with gold nanoparticles (FND–GNPs). This hybrid has unique applications, which cannot be realized by FNDs alone, such as two-in-one nanoheaters/thermometers. Nevertheless, the development of FND–GNP hybrids with highly uniform structures, high dispersity, and diverse functionalities remains challenging. In this study, we have designed FND composite quantum sensors (CQSs). In the first step, GNPs were directly grown from HAuCl4 on the surface of a FND coated with a thin layer of polydopamine (PDA), FND–PDA–GNP. The wet chemistry route provided the highly uniform structure of FND–GNPs in which the size of the GNPs can be controlled by changing the reaction conditions. In the second step, FND–PDA–GNP was further stabilized using an additional PDA layer (FND–PDA2–GNP) and was then modified with hyperbranched polyglycerol (HPG), FND–PDA2–GNP–HPG. The obtained composite exhibits excellent dispersity and aggregation resistance in salt-containing solutions. Finally, the one-pot functionalization of the amine-modified CQS was established from FND–PDA2–GNP, facilitating cell internalization, and thus controlled heating in a living cell was demonstrated.

Fluorescent nanodiamonds (FNDs) are very promising fluorophores for use in biosystems due to their high biocompatibility and photostability. To overcome their tendency to aggregate in physiological solutions, which severely limits the biological applications of FNDs, we developed a new non-covalent coating method using a block copolymer, PEG-b-P(DMAEMA-co-BMA), or proteins such as BSA and HSA. By simple mixing of the block copolymer with FNDs, the cationic DMAEMA and hydrophobic BMA moieties can strongly interact with the anionic and hydrophobic moieties on the FND surface, while the PEG block can form a shell to prevent the direct contact between FNDs. The polymer-coated FNDs, along with BSA- and HSA-coated FNDs, showed non-aggregation characteristics and maintained their size at the physiological salt concentration. The well-dispersed, polymer- or protein-coated FNDs in physiological solutions showed enhanced intracellular uptake, which was confirmed by CLSM. In addition, the biocompatibility of the coated FNDs was expressly supported by a cytotoxicity assay. Our simple non-covalent coating with the block copolymer, which can be easily modified by various chemical methods, projects a very promising outlook for future biomedical applications, especially in comparison with covalent coating or protein-based coating.

Fluorescent nanodiamonds (FNDs) with nitrogen-vacancycenters arepivotal for advancing quantum photonics and imaging through deterministicquantum state manipulation. However, deterministic integration ofquantum emitters into photonic devices remains a challenge due tothe need for high coupling efficiency and Purcell enhancement. Wereport a deterministic FND-integrated nanofocusing device achievedby assembling FNDs at a plasmonic waveguide tip through plasmonic-enhancedoptical trapping. This technique not only increases the emission rateby 58.6 times compared to isolated FNDs but also preferentially directsradiation into the waveguide at a rate 5.3 times higher than thatinto free space, achieving an exceptional figure-of-merit of ∼3000for efficient energy transfer. Our findings represent a significantstep toward deterministic integration in quantum imaging and communication,opening new avenues for quantum technology advancements.

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.

Fluorescent nanodiamond (FND) indicated that it has excellent biocompatibility and photostability,so it well suited for long-term labeling and tracking of stem cells. There are many reports concerning the factors controlling stem cell differentiation. However, still little knowledge about the biomaterials properties influence stem cell alive, growth and differentiation processing. In this study, we evaluate the effect of fluorescent nanodiamond in in vitro culture and differentiation of ucMSC into hepatocyte-like cell. Mesenchymal stem cells (MSCs) were isolated from the umbilical cord (UC) and CD markers were analyzed by flow cytometry and genes expression. For hepatic differentiation of UC-MSCs, cells were induced with HGF and DMSO treated. FND was supply in the experimental group which 10 g/ml in 4 hours. The FND uptake was detected of fluorescence intensity of FND in cells by flow cytometry and laser scan microscopy. The effect of FND into UCMSCs was not only evaluated by the cell alive and growth assay but also effective differentiation throughout morphology charging or gene expression levels of AFP, ALB, and HNF4 were determined by RT-PCR and real-time PCR. The result showed that the FND was well uptake in UCMSCs. It was no affected into ability of the cell alive and growth. The existence of FNDs does not disturb the functions of UC-MSCs differentiation into hepatocyte-like cell. FND can be utilized for the labeling and tracking of UC-MSCs and hepatocyte-like cell in homing research.

Nanoscale carbon materials hold great promise for biotechnological and biomedical applications. Fluorescent nanodiamond (FND) is a recent new addition to members of the nanocarbon family. Here, we report long-term in vivo imaging of FNDs in Caenorhabditis elegans (C. elegans) and explore the nano-biointeractions between this novel nanomaterial and the model organism. FNDs are introduced into wild-type C. elegans by either feeding them with colloidal FND solution or microinjecting FND suspension into the gonads of the worms. On feeding, bare FNDs stay in the intestinal lumen, while FNDs conjugated with biomolecules (such as dextran and bovine serum albumin) are absorbed into the intestinal cells. On microinjection, FNDs are dispersed in the gonad and delivered to the embryos and eventually into the hatched larvae in the next generation. The toxicity assessments, performed by employing longevity and reproductive potential as physiological indicators and measuring stress responses with use of reporter genes, show that FNDs are stable and nontoxic and do not cause any detectable stress to the worms. The high brightness, excellent photostability, and nontoxic nature of the nanomaterial have enabled continuous imaging of the whole digestive system and tracking of the cellular and developmental processes of the living organism for several days.

Nanodiamond is a promising carbon nanomaterial developed for biomedical applications. Here, we show fluorescent nanodiamond (FND) with the biocompatible properties that can be used for the labeling and tracking of neuronal differentiation and neuron cells derived from embryonal carcinoma stem (ECS) cells. The fluorescence intensities of FNDs were increased by treatment with FNDs in both the mouse P19 and human NT2/D1 ECS cells. FNDs were taken into ECS cells; however, FNDs did not alter the cellular morphology and growth ability. Moreover, FNDs did not change the protein expression of stem cell marker SSEA-1 of ECS cells. The neuronal differentiation of ECS cells could be induced by retinoic acid (RA). Interestingly, FNDs did not affect on the morphological alteration, cytotoxicity and apoptosis during the neuronal differentiation. Besides, FNDs did not alter the cell viability and the expression of neuron-specific marker β-III-tubulin in these differentiated neuron cells. The existence of FNDs in the neuron cells can be identified by confocal microscopy and flow cytometry. Together, FND is a biocompatible and readily detectable nanomaterial for the labeling and tracking of neuronal differentiation process and neuron cells from stem cells.

Facile preparation of fluorescent nanodiamond based polymer nanoparticles via ring-opening polymerization and their biological imaging.

Fluorescent nanodiamonds engage innate immune effector cells: A potential vehicle for targeted anti-tumor immunotherapy

In recent years, nanodiamond has emerged as a promising biomaterial for diagnostic and therapeutic applications. Fluorescent nanodiamond (FND) containing nitrogen‐vacancy centers is a new addition to the nanodiamond family. The fluorophore produced by nitrogen‐vacancy made FND extremely photostable. Furthermore, the high refractive index makes FNDs visible under light microscopy. In previous studies, FND has been reported to have outstanding biocompatibility and high uptake rate in various cell types. However, the application of FND on neurons or nervous tissue remains elusive. In order to study the compatibility of FND on neurons, the viability and morphological alteration of neurons after treated with FND were examined. Dissociated primary neurons from both central nervous system (CNS) and peripheral nervous system (PNS) were cultured in the presence of FND and neither exhibited a reduction in viability. However, we did observe a FND dosage‐dependent decrease in neurite length in both CNS and PNS neurons. Time‐lapse live cell imaging suggested that the reduction of neurite length was due to the spatial hindrance of FND on advancing neuronal growth cone. Additionally, neuronal uptake of FNDs was confirmed using confocal microscopy and flow cytometry. These results indicated that FND exhibited low neuronal toxicity and can be readily taken into neurons. However, high dosage of FND may interfere with neurite elongation and should be taken into consideration when applications involve actively growing neurites (e.g. axon regeneration).Grant Funding Source: Supported by National Science Council of Taiwan

Due to their stable fluorescence, biocompatibility, and amenability to functionalization, fluorescent nanodiamonds (FND) are promising materials for long term cell labeling and tracking. However, transporting them to the cytosol remains a major challenge, due to low internalization efficiencies and endosomal entrapment. Here, nanostraws in combination with low voltage electroporation pulses are used to achieve direct delivery of FND to the cytosol. The nanostraw delivery leads to efficient and rapid FND transport into cells compared to when incubating cells in a FND-containing medium. Moreover, whereas all internalized FND delivered by incubation end up in lysosomes, a significantly larger proportion of nanostraw-injected FND are in the cytosol, which opens up for using FND as cellular probes. Furthermore, in order to answer the long-standing question in the field of nano-biology regarding the state of the cell membrane on hollow nanostructures, live cell stimulated emission depletion (STED) microscopy is performed to image directly the state of the membrane on nanostraws. The time-lapse STED images reveal that the cell membrane opens entirely on top of nanostraws upon application of gentle electrical pulses, which supports the hypothesis that many FND are delivered directly to the cytosol, avoiding endocytosis and lysosomal entrapment.

Fluorescent nanodiamonds (FNDs) have generated immense interest as fluorescent probes for biomedical imaging due to their unparalleled photostability and potential biocompatibility. Diamond can become fluorescent due to defects; in particular, nitrogen-vacancy (NV) centers in diamond are fluorescent sources with remarkable optical properties. FNDs containing NV centers do not photo-bleach or blink, their fluorescence emission can be modulated with a magnetic field making them one of the most sensitive magnetic field sensors, and they have fluorescence lifetime longer than fluorescent biomolecules. Commercial cost-effective availability along with method development for easy functionalization and imaging have promoted vigorous research on using FNDs as versatile bioimaging probes. Methods to coat FNDs with silica for easy functionalization for biomedical applications and to image FNDs background-free in vitro and in vivo by applying an alternating magnetic field with a conventional fluorescence microscope have been achieved. Functionalized FNDs have been used to track biomolecules in vitro and in vivo. For future use in humans and regulatory approval, it is necessary to study biodistribution, biotoxicity, and clearance, all of which have been studied in animals. This review gives an overview of the entire spectrum of FND related research.

Fluorescent nanodiamonds (FNDs) are carbon-based nanomaterials that emit bright, photostable fluorescence and exhibit a modifiable surface chemistry. Myeloid-derived suppressor cells (MDSCs) are an immunosuppressive cell population known to expand in cancer patients and contribute to worse patient outcomes. To target MDSC, glycidol-coated FND were conjugated with antibodies against the murine MDSC markers, CD11b and GR1 (dual-Ab FND). In vitro, dual-Ab FND uptake by murine MDSC was significantly higher than IgG-coated FND (94.7% vs. 69.0%, p < 0.05). In vivo, intra-tumorally injected dual-Ab FND primarily localized to the tumor 2 and 24 h post-injection, as measured by in vivo fluorescence imaging and flow cytometry analysis of the spleen and tumor. Dual-Ab FND were preferentially taken up by intra-tumoral MDSC, representing 87.1% and 83.0% of FND+ cells in the tumor 2 and 24 h post-injection, respectively. Treatment of mice with anti-PD-L1 immunotherapy prior to intra-tumoral injection of dual-Ab FND did not significantly alter the uptake of FND by MDSC. These results demonstrate the ability of our novel dual-antibody conjugated FND to target MDSC and reveal a potential strategy for targeted delivery to other specific immune cell populations in future cancer research.