A tumor-targeted, intracellular activatable and theranostic nanodiamond drug platform for strongly enhanced in vivo antitumor therapy

Nanodiamond-Based Sensing: A revolution for biosensors in capturing elusive bio-signals in living cells

Cells constantly produce elusive bio-signals, such as cellular forces, free radicals, and molecular interactions, that are important for understanding diseases and treatment effects. However, detecting these signals is challenging because of issues with sensitivity, specificity, and the complexity of biological systems. Owing to their unique properties, nanodiamonds have emerged as a promising platform for detecting such elusive bio-signals, providing enhanced precision and effectiveness in diagnostics and therapies. In this review, we explore the detection of intracellular elusive bio-signals using nitrogen-vacancy (NV) centers in nanodiamonds, presenting case studies on their applications in cell force, free radicals, molecular interactions, and nanoscale thermometry. Moreover, we explore the design and applications of nanodiamonds as nanocarriers in quantum sensors and drug delivery systems.

Recent progress in cancer vaccines and nanovaccines

Vaccine science, nanotechnology, and immunotherapy are at the forefront of cancer treatment strategies, each offering significant potential for enhancing tumor-specific immunity and establishing long-lasting immune memory to prevent tumor recurrence. Despite the promise of these personalized and precision-based anti-cancer approaches, challenges such as immunosuppression, suboptimal immune activation, and T-cell exhaustion continue to hinder their effectiveness. The limited clinical success of cancer vaccines often stems from difficulties in identifying effective antigens, efficiently targeting immune cells, lymphoid organs, and the tumor microenvironment, overcoming immune evasion, enhancing immunogenicity, and avoiding lysosomal degradation. However, numerous studies have demonstrated that integrating nanotechnology with immunotherapeutic strategies in vaccine development can overcome these challenges, leading to potent antitumor immune responses and significant progress in the field. This review highlights the critical components of cancer vaccine and nanovaccine strategies for immunomodulatory antitumor therapy. It covers general vaccine strategies, types of vaccines, antigen forms, nanovaccine platforms, challenges faced, potential solutions, and key findings from preclinical and clinical studies, along with future perspectives. To fully unlock the potential of cancer vaccines and nanovaccines, precise immunological monitoring during early-phase trials is essential. This approach will help identify and address obstacles, ultimately expanding the available options for patients who are resistant to conventional cancer immunotherapies.

Fluorescent Nanocarbons: From Synthesis and Structure to Cancer Imaging and Therapy

Nanocarbons are emerging at the forefront of nanoscience, with diverse carbon nanoforms emerging over the past two decades. Early cancer diagnosis and therapy, driven by advanced chemistry techniques, play a pivotal role in mitigating mortality rates associated with cancer. Nanocarbons, with an attractive combination of well-defined architectures, biocompatibility, and nanoscale dimension, offer an incredibly versatile platform for cancer imaging and therapy. This paper aims to review the underlying principles regarding the controllable synthesis, fluorescence origins, cellular toxicity, and surface functionalization routes of several classes of nanocarbons: carbon nanodots, nanodiamonds, carbon nanoonions, and carbon nanohorns. This review also highlights recent breakthroughs regarding the green synthesis of different nanocarbons from renewable sources. It also presents a comprehensive and unified overview of the latest cancer-related applications of nanocarbons and how they can be designed to interface with biological systems and work as cancer diagnostics and therapeutic tools. The commercial status for large-scale manufacturing of nanocarbons is also presented. Finally, it proposes future research opportunities aimed at engendering modifiable and high-performance nanocarbons for emerging applications across medical industries. This work is envisioned as a cornerstone to guide interdisciplinary teams in crafting fluorescent nanocarbons with tailored attributes that can revolutionize cancer diagnostics and therapy.

Nanodiamonds in biomedical research: Therapeutic applications and beyond

Nanodiamonds (NDs) comprise a family of carbon-based nanomaterials (i.e. diameter <100 nm) with the same sp3 lattice structure that gives natural diamonds their exceptional hardness and electrical insulating properties. Among all carbon nanomaterials-e.g. carbon nanotubes, nanodots, and fullerenes-NDs are of particular interest for biomedical applications because they offer high biocompatibility, stability in vivo, and a dynamic surface chemistry that can be manipulated to perform a seemingly limitless variety of ultra-specific tasks. NDs are already deepening our understanding of basic biological processes, while numerous laboratories continue studying these nanomaterials with an aim of making seismic improvements in the prevention, diagnosis, and treatment of human diseases. This review surveys approximately 2,000 the most recent articles published in the last 5 years and includes references to more than 150 of the most relevant publications on the biomedical applications of NDs. The findings are categorized by contemporary lines of investigation based on potential applications, namely: genetics and gene editing, drug delivery systems, neural interfacing, biomedical sensors, synthetic biology, and organ and tissue regeneration. This review also includes a brief background of NDs and the methods currently developed for their synthesis and preparation. Finally, recommendations for future investigations are offered.

Nanovaccines: An effective therapeutic approach for cancer therapy

Cancer vaccines hold considerable promise for the immunotherapy of solid tumors. Nanomedicine offers several strategies for enhancing vaccine effectiveness. In particular, molecular or (sub) cellular vaccines can be delivered to the target lymphoid tissues and cells by nanocarriers and nanoplatforms to increase the potency and durability of antitumor immunity and minimize negative side effects. Nanovaccines use nanoparticles (NPs) as carriers and/or adjuvants, offering the advantages of optimal nanoscale size, high stability, ample antigen loading, high immunogenicity, tunable antigen presentation, increased retention in lymph nodes, and immunity promotion. To induce antitumor immunity, cancer vaccines rely on tumor antigens, which are administered in the form of entire cells, peptides, nucleic acids, extracellular vesicles (EVs), or cell membrane-encapsulated NPs. Ideal cancer vaccines stimulate both humoral and cellular immunity while overcoming tumor-induced immune suppression. Herein, we review the key properties of nanovaccines for cancer immunotherapy and highlight the recent advances in their development based on the structure and composition of various (including synthetic and semi (biogenic) nanocarriers. Moreover, we discuss tumor cell-derived vaccines (including those based on whole-tumor-cell components, EVs, cell membrane-encapsulated NPs, and hybrid membrane-coated NPs), nanovaccine action mechanisms, and the challenges of immunocancer therapy and their translation to clinical applications.

Zero-Dimensional Carbon Nanomaterials for Fluorescent Sensing and Imaging

Advances in nanotechnology and nanomaterials have attracted considerable interest and play key roles in scientific innovations in diverse fields. In particular, increased attention has been focused on carbon-based nanomaterials exhibiting diverse extended structures and unique properties. Among these materials, zero-dimensional structures, including fullerenes, carbon nano-onions, carbon nanodiamonds, and carbon dots, possess excellent bioaffinities and superior fluorescence properties that make these structures suitable for application to environmental and biological sensing, imaging, and therapeutics. This review provides a systematic overview of the classification and structural properties, design principles and preparation methods, and optical properties and sensing applications of zero-dimensional carbon nanomaterials. Recent interesting breakthroughs in the sensitive and selective sensing and imaging of heavy metal pollutants, hazardous substances, and bioactive molecules as well as applications in information encryption, super-resolution and photoacoustic imaging, and phototherapy and nanomedicine delivery are the main focus of this review. Finally, future challenges and prospects of these materials are highlighted and envisaged. This review presents a comprehensive basis and directions for designing, developing, and applying fascinating fluorescent sensors fabricated based on zero-dimensional carbon nanomaterials for specific requirements in numerous research fields.

pH-Sensitive nanodiamond co-delivery of retinal and doxorubicin boosts breast cancer chemotherapy

Herein for the first time we take the advantage of nanodiamonds (NDs) to covalently immobilize all-trans retinal (NPA) by an imine bond, allowing pH-mediated drug release. DOX is then physically adsorbed onto NPA to form an NPA@D co-loaded double drug in the sodium citrate medium, which is also susceptible to pH-triggered DOX dissociation. The cytotoxicity results showed that NPA@D could markedly inhibit the growth of DOX-sensitive MCF-7 cells in a synergetic way compared to the NP@D system of single-loaded DOX, while NPA basically showed no cytotoxicity and weak inhibition of migration. In addition, NPA@D can overcome the drug resistance of MCF-7/ADR cells, indicating that this nanodrug could evade the pumping of DOX by drug-resistant cells, but free DOX is nearly ineffective against these cells. More importantly, the fluorescence imaging of tumor-bearing mice in vivo and ex vivo demonstrated that the NPA@D was mainly accumulated in the tumor site rather than any other organ by intraperitoneal injection after 24 h, in which the fluorescence intensity of NPA@D was 19 times that of the free DOX, suggesting that a far reduced off-target effect and side effects would be expected. Therefore, this work presents a new paradigm for improving chemotherapy and reversing drug resistance using the ND platform for co-delivery of DOX and ATR.

Carbon Nanomaterials (CNMs) in Cancer Therapy: A Database of CNM-Based Nanocarrier Systems

Carbon nanomaterials (CNMs) are an incredibly versatile class of materials that can be used as scaffolds to construct anticancer nanocarrier systems. The ease of chemical functionalisation, biocompatibility, and intrinsic therapeutic capabilities of many of these nanoparticles can be leveraged to design effective anticancer systems. This article is the first comprehensive review of CNM-based nanocarrier systems that incorporate approved chemotherapy drugs, and many different types of CNMs and chemotherapy agents are discussed. Almost 200 examples of these nanocarrier systems have been analysed and compiled into a database. The entries are organised by anticancer drug type, and the composition, drug loading/release metrics, and experimental results from these systems have been compiled. Our analysis reveals graphene, and particularly graphene oxide (GO), as the most frequently employed CNM, with carbon nanotubes and carbon dots following in popularity. Moreover, the database encompasses various chemotherapeutic agents, with antimicrotubule agents being the most common payload due to their compatibility with CNM surfaces. The benefits of the identified systems are discussed, and the factors affecting their efficacy are detailed.

The Antibacterial Effect, Biocompatibility, and Osteogenesis of Vancomycin-Nanodiamond Composite Scaffold for Infected Bone Defects

Purpose

The repair and treatment of infected bone defects (IBD) is a common challenge faced by orthopedic clinics, medical materials science, and tissue engineering.

Methods

Based on the treatment requirements of IBD, we utilized multidisciplinary knowledge from clinical medicine, medical materials science, and tissue engineering to construct a high-efficiency vancomycin sustained-release system with nanodiamond (ND) and prepare a composite scaffold. Its effect on IBD treatment was assessed from materials, cytology, bacteriology, and zoology perspectives.

Results

The results demonstrated that the Van-ND-45S5 scaffold exhibited an excellent antibacterial effect, biocompatibility, and osteogenesis in vitro. Moreover, an efficient animal model of IBD was established, and a Van-ND-45S5 scaffold was implanted into the IBD. Radiographic and histological analyses and bone repair-related protein expression, confirmed that the Van-ND-45S5 scaffold had good biocompatibility and osteogenic and anti-infective activities in vivo.

Conclusion

Collectively, our findings support that the Van-ND-45S5 scaffold is a promising new material and approach for treating IBD with good antibacterial effects, biocompatibility, and osteogenesis.

A nanodiamond chemotherapeutic folate receptor-targeting prodrug with triggerable drug release

Cancer chemotherapy is often accompanied by severe off-target effects that both damage quality of life and can decrease therapeutic compliance. This could be minimized through selective delivery of cytotoxic agents directly to the cancer cells. This would decrease the drug dose, consequently minimizing side effects and cost. With this goal in mind, a dual-gated folate-functionalized nanodiamond drug delivery system (NPFSSD) for doxorubicin with activatable fluorescence and cytotoxicity has been prepared. Both the cytotoxic activity and the fluorescence of doxorubicin (DOX) are quenched when it is covalently immobilized on the nanodiamond. The NPFSSD is preferentially uptaken by cancer cells overexpressing the folate receptor. Then, once inside a cell, the drug is preferentially released within tumor cells due to their high levels of endogenous of glutathione, required for releasing DOX through cleavage of a disulfide linker. Interestingly, once free DOX is loaded onto the nanodiamond, it can also evade resistance mechanisms that use protein pumps to remove drugs from the cytoplasm. This nanodrug, used in an in vivo model with local injection of drugs, effectively inhibits tumor growth with fewer side effects than direct injection of free DOX, providing a potentially powerful platform to improve therapeutic outcomes.

Sustained delivery of gambogic acid from mesoporous rod-structure hydroxyapatite for efficient in vitro cancer therapy

Inspired by the critical role of nanocarrier in biomaterials modification, we synthesized a mesoporous rod-structure hydroxyapatite (MR-HAp) nanoparticles for boosting gambogic acid (GA) bioavailability in cells and improving the tumor therapy. As expected, the GA loading ratio of MR-HAp was up to about 96.97% and GA-loaded MR-HAp (MR-HAp/GA) demonstrates a sustained release performance. Furthermore, a substantial improvement was observed in inhibiting the cell proliferation and inducing the apoptosis of HeLa cells, as the cell viability was decreased to 89.6% and the apoptosis was increased to 49.2% when the cells treated with MR-HAp/GA at a GA concentration of 1 μg/mL for 72 h. The remarkable inhibition effect of cell proliferation and the enhanced inducing apoptosis are attributed to the increasing intracellular reactive oxygen species level and reduced mitochondrial membrane potential. This result provides a promising and facile approach for highly efficient tumor treatment.

Emerging pro-drug and nano-drug strategies for gemcitabine-based cancer therapy

Gemcitabine has been extensively applied in treating various solid tumors. Nonetheless, the clinical performance of gemcitabine is severely restricted by its unsatisfactory pharmacokinetic parameters and easy deactivation mainly because of its rapid deamination, deficiencies in deoxycytidine kinase (DCK), and alterations in nucleoside transporter. On this account, repeated injections with a high concentration of gemcitabine are adopted, leading to severe systemic toxicity to healthy cells. Accordingly, it is highly crucial to fabricate efficient gemcitabine delivery systems to obtain improved therapeutic efficacy of gemcitabine. A large number of gemcitabine pro-drugs were synthesized by chemical modification of gemcitabine to improve its biostability and bioavailability. Besides, gemcitabine-loaded nano-drugs were prepared to improve the delivery efficiency. In this review article, we introduced different strategies for improving the therapeutic performance of gemcitabine by the fabrication of pro-drugs and nano-drugs. We hope this review will provide new insight into the rational design of gemcitabine-based delivery strategies for enhanced cancer therapy.

Tumor Microenvironment-Activated Theranostics Nanozymes for Fluorescence Imaging and Enhanced Chemo-Chemodynamic Therapy of Tumors

Chemodynamic therapy (CDT) is widely explored for tumor-specific therapy by converting endogenous H₂O₂ to lethal ·OH to destroy cancer cells. However, ·OH scavenging by glutathione (GSH) and insufficient intratumoral H₂O₂ levels seriously hinder the application of CDT. Herein, we reported the fabrication of copper ion-doped ZIF-8 loaded with gold nanozymes and doxorubicin hydrochloride (DOX) for the chemotherapy and CDT synergistic treatment of tumors with the assistance of tumor microenvironment (TME)-activated fluorescence imaging. The Cu²⁺-doped ZIF-8 shell was gradually degraded to release DOX and gold nanoclusters responding to the acidic TME. The fluorescence signal of the tumor region was acquired after the quenched fluorescence of the gold nanoclusters by Cu²⁺ and DOX by aggregation-induced quenching was turned on because of the interaction of GSH with Cu²⁺ and the release of free DOX. The Cu²⁺ ions could deplete the GSH via redox reactions and the generated Cu⁺ could convert internal H₂O₂ to ·OH for tumor CDT. The chemotherapeutic effect of DOX was strengthened through drug efflux inhibition and drug sensitivity increase due to the consumption of GSH and ·OH burst. Moreover, DOX could raise the level of H₂O₂ and augment the effect of CDT. In addition, the fluorescent gold nanoclusters not only served as a peroxidase to convert H₂O₂ to ·OH but also employed as an oxidase to consume GSH, resulting in the amplification of chemotherapy and CDT. This work presents an approach to construct tumor microenvironment-activated theranostic probes without external stimuli and to achieve the tumor elimination through cascade reactions and synergistic treatment.

The influence of differently functionalized nanodiamonds on proliferation, apoptosis and EMT/MET phenomena in 2D and 3D tumor cell cultures

Nanodiamonds (ND) have been suggested to have several potential uses in biomedicine, since they are seemingly biocompatible. However, data about the biological effects of ND in physiological conditions are scarce. In this study, we observed that prostate cancer cells (LNCaP) and breast cancer cells (MDA-MB-231 and MCF-7) cultured with ND show morphological changes and altered gene and protein expression. In 2D we could detect only slight effects of ND on cell growth and apoptosis induction. Therefore, we applied different functionalized ND in a novel 3D cell culture model that reflects better tissue conditions compared to conventional 2D cell cultures. In 3D proliferation was reduced by all nanoparticles and benzoquinone functionalized ND induced cell death. As the used decellularized scaffold maintains the tissue architecture, we could also functionally investigate if nanoparticles induce cell migration into deeper layers and if they display markers of Mesenchymal Epithelial Transition (MET). We detected in more mesenchymal and invasive growing MDA-MB-231 cells less vimentin and increased levels of pan-cytokeratin expression after ND treatment, which indicates a MET induction. Our observations suggest that the presence of ND stimulates MET, with varying degrees of transition. The observation that ND do not support the opposite, EMT, is beneficial, since EMT is known to play a major role in tumor metastasis. However, a special focus should be placed on the characterization of biological effects to be able to guarantee the safety of ND in clinical use.

Nanodiamonds and hydrogen-substituted graphdiyne heteronanostructure for the sensitive impedimetric aptasensing of myocardial infarction and cardiac troponin I

A novel heteronanostructure of nanodiamonds (NDs) and hydrogen-substituted graphdiyne (HsGDY) (denoted as HsGDY@NDs) was prepared for the impedimetric aptasensing of biomarkers such as myoglobin (Myo) and cardiac troponin I (cTnI). Basic characterizations revealed that the HsGDY@NDs were composed of nanospheres with sizes of 200-500 nm. In these nanospheres, NDs were embedded within the HsGDY network. The HsGDY@NDs nanostructure, which integrated the good chemical stability and three-dimensional porous networks of HsGDY, and the good biocompatibility and electrochemical activity of NDs, could immobilize diverse aptamer strands and recognize target biomarkers. Compared with HsGDY- and NDs-based aptasensors, the HsGDY@NDs-based aptasensors exhibited superior sensing performances for Myo and cTnI, giving low detection limits of 6.29 and 9.04 fg mL^-1 for cTnI and Myo, respectively. In addition, the HsGDY@NDs-based aptasensors exhibited high selectivity, good stability, reproducibility, and acceptable applicability in real human serum. Thus, the construction of HsGDY@NDs-based aptasensor is expected to broaden the application of porous organic frameworks in the sensing field and provide a prospective approach for the early detection of disease biomarkers.