Pre-targeting with ultra-small nanoparticles: boron carbon dots as drug candidates for boron neutron capture therapy

Strategic Assessment of Boron-Enriched Carbon Dots/Naproxen: Diagnostic, Toxicity, and In Vivo Therapeutic Evaluation

Cancer is a significant global public health concern, ranking as the leading cause of mortality worldwide. This study thoroughly explores boron-doped carbon dots (B-CDs) through a simple/rapid microwave-assisted approach and their versatile applications in cancer therapy. The result was highly uniform particles with an average diameter of approximately 4 nm. B-CDs exhibited notable properties, including strong fluorescence with a quantum yield of 33%. Colloid stability tests revealed their robustness within a pH range of 6-12, NaCl concentrations up to 0.5 M, and temperatures ranging from 30 to 60 °C. The study also delved into the kinetics of naproxen release from B-CDs as a drug delivery system. The loading efficacy of naproxen exceeded 55.56%. Under varying pH conditions, the release of naproxen from B-CDs conformed to the Peppas-Sahlin model, demonstrating the potential of Naproxen-loaded CDs for cancer drug delivery. In vitro cytotoxicity assessments, conducted using the CCK-8 Assay and flow cytometry, consistently indicated low toxicity with average cell viability exceeding 80%. An in vivo toxicity test on female mice administered 20 mg/kg of B-CDs for 31 days revealed reversible histological changes in the liver and kidneys, while the pancreas remained unaffected. Importantly, B-CDs did not impact the mice's physical behavior, body weight, or survival. In vivo experiments targeting benzo(a)pyrene-induced fibrosarcoma demonstrated the efficacy of B-CDs as naproxen carriers in the treatment of cancer. This in vivo study provides a thorough comprehension of B-CDs synthesis and toxicity and their potential applications in cancer therapy and drug delivery systems.

Next generation of boron neutron capture therapy (BNCT) agents for cancer treatment

Boron neutron capture therapy (BNCT) is one of the most promising treatments among neutron capture therapies due to its long-term clinical application and unequivocally obtained success during clinical trials. Boron drug and neutron play an equivalent crucial role in BNCT. Nevertheless, current clinically used l-boronophenylalanine (BPA) and sodium borocaptate (BSH) suffer from large uptake dose and low blood to tumor selectivity, and that initiated overwhelm screening of next generation of BNCT agents. Various boron agents, such as small molecules and macro/nano-vehicles, have been explored with better success. In this featured article, different types of agents are rationally analyzed and compared, and the feasible targets are shared to present a perspective view for the future of BNCT in cancer treatment. This review aims at summarizing the current knowledge of a variety of boron compounds, reported recently, for the application of BCNT.

Optimizing Boron Neutron Capture Therapy (BNCT) to Treat Cancer: An Updated Review on the Latest Developments on Boron Compounds and Strategies

Boron neutron capture therapy (BNCT) is a tumor-selective particle radiotherapy. It combines preferential boron accumulation in tumors and neutron irradiation. The recent initiation of BNCT clinical trials employing hospital-based accelerators rather than nuclear reactors as the neutron source will conceivably pave the way for new and more numerous clinical trials, leading up to much-needed randomized trials. In this context, it would be interesting to consider the implementation of new boron compounds and strategies that will significantly optimize BNCT. With this aim in mind, we analyzed, in this review, those articles published between 2020 and 2023 reporting new boron compounds and strategies that were proved therapeutically useful in in vitro and/or in vivo radiobiological studies, a critical step for translation to a clinical setting. We also explored new pathologies that could potentially be treated with BNCT and newly developed theranostic boron agents. All these radiobiological advances intend to solve those limitations and questions that arise during patient treatment in the clinical field, with BNCT and other therapies. In this sense, active communication between clinicians, radiobiologists, and all disciplines will improve BNCT for cancer patients, in a cost- and time-effective way.

Boron Vehiculating Nanosystems for Neutron Capture Therapy in Cancer Treatment

Boron neutron capture therapy is a low-invasive cancer therapy based on the neutron fission process that occurs upon thermal neutron irradiation of ¹⁰B-containing compounds; this process causes the release of alpha particles that selectively damage cancer cells. Although several clinical studies involving mercaptoundecahydro-closo-dodecaborate and the boronophenylalanine-fructose complex are currently ongoing, the success of this promising anticancer therapy is hampered by the lack of appropriate drug delivery systems to selectively carry therapeutic concentrations of boron atoms to cancer tissues, allowing prolonged boron retention therein and avoiding the damage of healthy tissues. To achieve these goals, numerous research groups have explored the possibility to formulate nanoparticulate systems for boron delivery. In this review. we report the newest developments on boron vehiculating drug delivery systems based on nanoparticles, distinguished on the basis of the type of carrier used, with a specific focus on the formulation aspects.

Sustainable Synthesis of Highly Biocompatible 2D Boron Nitride Nanosheets

2D ultrafine nanomaterials today represent an emerging class of materials with very promising properties for a wide variety of applications. Biomedical fields have experienced important new achievements with technological breakthroughs obtained from 2D materials with singular properties. Boron nitride nanosheets are a novel 2D layered material comprised of a hexagonal boron nitride network (BN) with interesting intrinsic properties, including resistance to oxidation, extreme mechanical hardness, good thermal conductivity, photoluminescence, and chemical inertness. Here, we investigated different methodologies for the exfoliation of BN nanosheets (BNNs), using ball milling and ultrasound processing, the latter using both an ultrasound bath and tip sonication. The best results are obtained using tip sonication, which leads to the formation of few-layered nanosheets with a narrow size distribution. Importantly, it was observed that with the addition of pluronic acid F127 to the medium, there was a significant improvement in the BN nanosheets (BNNs) production yield. Moreover, the resultant BNNs present improved stability in an aqueous solution. Cytotoxicity studies performed with HeLa cells showed the importance of taking into account the possible interferences of the nanomaterial with the selected assay. The prepared BNNs coated with pluronic presented improved cytotoxicity at concentrations up to 200 μg mL^-1 with more than 90% viability after 24 h of incubation. Confocal microscopy also showed high cell internalization of the nanomaterials and their preferential biodistribution in the cell cytoplasm.

Tailored hyaluronic acid-based nanogels as theranostic boron delivery systems for boron neutron cancer therapy

Boron-rich nanocarriers possess great potential for advanced boron neutron capture therapy (BNCT) as an effective radiation treatment for invasive malignant tumors. If additionally, they can be imaged in a non-invasive and real-time manner allowing the assessment of local boron concentration, they could serve for dose calculation and image-guided BNCT to enhance tumor treatment efficacy. To meet this challenge, this study describes the design of a theranostic nanogel, enriched in ¹⁰B and fluorescent dye, to achieve selective imaging, and sufficient accumulation of boron at the tumor site. The boron-rich and fluorescent nanogels can be easily obtained via temperature triggered-assembly of hyaluronic acid (HA) modified with a thermoresponsive terpolymer. The latter was specifically designed to enable the efficient encapsulation of the fluorescent dye – an aza‑boron-dipyrromethene (aza-BODIPY) – linked to ¹⁰B-enriched sodium borocaptate (BSH), in addition to induce nanogel formation below room temperature, and to enable their core-crosslinking by hydrazone bond formation. The HA nanogel considerably concentrates aza-BODIPY-BSH into the hydrophobic nanodomains made of the terpolymer chains. Here, we present the detailed synthesis of the HA-terpolymer conjugate, nanogel formation, and characterization in terms of size, morphology, and stability upon storage, as well as the biological behavior of the boron nanocarrier using real-time fluorescence imaging in cells and in vivo. This work suggested the potential of the theranostic HA nanogel as a boron delivery system for the implementation of BNCT in brain cancer and sarcoma.

Transforming Nuclear Medicine with Nanoradiopharmaceuticals

Nuclear medicine is expected to make major advances in cancer diagnosis and therapy; tumor-targeted radiopharmaceuticals preferentially eradicate tumors while causing minimal damage to healthy tissues. The current scope of nuclear medicine can be significantly expanded by integration with nanomedicine, which utilizes nanoparticles for cancer diagnosis and therapy by capitalizing on the increased surface area-to-volume ratio, the passive/active targeting ability and high loading capacity, the greater interaction cross section with biological tissues, the rich surface properties of nanomaterials, the facile decoration of nanomaterials with a plethora of functionalities, and the potential for multiplexing several functionalities within one construct. This review provides a comprehensive discussion of nuclear nanomedicine using tumor-targeted nanoparticles for cancer radiation therapy with either pre-embedded radionuclides or nonradioactive materials which can be extrinsically triggered using various external nuclear particle sources to produce in situ radioactivity. In addition, it describes the prospect of combining nuclear nanomedicine with other modalities to enable synergistically enhanced combination therapies. The review also discusses advances in the fabrication of radionuclides as well as describes laser ablation technologies for producing nanoradiopharmaceuticals, which combine the ease of production with exceptional purity and rapid biodegradability, along with additional imaging or therapeutic functionalities. From a practical standpoint, these attributes of nanoradiopharmaceuticals may provide distinct advantages in diagnostic/therapeutic sensitivity and specificity, imaging resolution, and scalability of turnkey platforms. Coupling image-guided targeted radiation therapy with the possibility of in situ activation of nanomaterials as well as combining with other therapeutic modalities using a multifunctional nanoplatform could herald an era of exciting technological and therapeutic advances to radically transform the landscape of nuclear medicine. The review concludes with a discussion of current challenges and presents the authors' views on future opportunities to stimulate further research in this rewarding field of high societal impact.

Recent advances in nanoscale targeted therapy of HER2-positive breast cancer

Breast cancer is the second leading cause of death among women with high mortality rates worldwide. The exceptionally fast rate of metastasis, the emergence of drug-resistant mechanisms, and the occurrence of inadvertent side effects by cytotoxic chemotherapies often make conventional chemotherapy and immunotherapy treatments ineffective. Similar to other solid tumors, breast cancer can develop unique cellular and molecular characteristics forming an atypical permissive tumor microenvironment (TME). Due to the unique features of TME, cancer cells can further proliferate and coadapt with the stromal cells and evade immunosurveillance. aberrantly abundantly express various pieces of molecular machinery (the so-called oncomarkers) in favor of their survival, progression, metastasis, and further invasion. Such overexpressed oncomarkers can be exploited in the targeted therapy of cancer. Among breast cancer oncomarkers, epidermal growth factor receptors, particularly HER2, are considered as clinically valid molecular targets not only for the thorough diagnosis but also for the targeted therapy of the disease using different conventional and advanced nanoscale treatment modalities. This review aims to elaborate on the recent advances in the targeted therapy of HER2-positive breast cancer, and discuss various types of multifunctional nanomedicines/theranostics, and antibody-/aptamer-drug conjugates.

Carboranes as unique pharmacophores in antitumor medicinal chemistry

Carborane is a carbon-boron molecular cluster that can be viewed as a 3D analog of benzene. It features special physical and chemical properties, and thus has the potential to serve as a new type of pharmacophore for drug design and discovery. Based on the relative positions of two cage carbons, icosahedral closo-carboranes can be classified into three isomers, ortho-carborane (o-carborane, 1,2-C2B10H12), meta-carborane (m-carborane, 1,7-C2B10H12), and para-carborane (p-carborane, 1,12-C2B10H12), and all of them can be deboronated to generate their nido- forms. Cage compound carborane and its derivatives have been demonstrated as useful chemical entities in antitumor medicinal chemistry. The applications of carboranes and their derivatives in the field of antitumor research mainly include boron neutron capture therapy (BNCT), as BNCT/photodynamic therapy dual sensitizers, and as anticancer ligands. This review summarizes the research progress on carboranes achieved up to October 2021, with particular emphasis on signaling transduction pathways, chemical structures, and mechanistic considerations of using carboranes.

In Vivo Evaluation of Multifunctional Gold Nanorods for Boron Neutron Capture and Photothermal Therapies

The incidence and mortality of cancer demand more innovative approaches and combination therapies to increase treatment efficacy and decrease off-target side effects. We describe a boron-rich nanoparticle composite with potential applications in both boron neutron capture therapy (BNCT) and photothermal therapy (PTT). Our strategy is based on gold nanorods (AuNRs) stabilized with polyethylene glycol and functionalized with the water-soluble complex cobalt bis(dicarbollide) ([3,3'-Co(1,2-C₂B₉H₁₁)₂]^-), commonly known as COSAN. Radiolabeling with the positron emitter copper-64 (⁶⁴Cu) enabled in vivo tracking using positron emission tomography imaging. ⁶⁴Cu-labeled multifunctionalized AuNRs proved to be radiochemically stable and capable of being accumulated in the tumor after intravenous administration in a mouse xenograft model of gastrointestinal cancer. The resulting multifunctional AuNRs showed high biocompatibility and the capacity to induce local heating under external stimulation and trigger cell death in heterogeneous cancer spheroids as well as the capacity to decrease cell viability under neutron irradiation in cancer cells. These results position our nanoconjugates as suitable candidates for combined BNCT/PTT therapies.

Theranostics in Boron Neutron Capture Therapy

Boron neutron capture therapy (BNCT) has the potential to specifically destroy tumor cells without damaging the tissues infiltrated by the tumor. BNCT is a binary treatment method based on the combination of two agents that have no effect when applied individually: ¹⁰B and thermal neutrons. Exclusively, the combination of both produces an effect, whose extent depends on the amount of ¹⁰B in the tumor but also on the organs at risk. It is not yet possible to determine the ¹⁰B concentration in a specific tissue using non-invasive methods. At present, it is only possible to measure the ¹⁰B concentration in blood and to estimate the boron concentration in tissues based on the assumption that there is a fixed uptake of ¹⁰B from the blood into tissues. On this imprecise assumption, BNCT can hardly be developed further. A therapeutic approach, combining the boron carrier for therapeutic purposes with an imaging tool, might allow us to determine the ¹⁰B concentration in a specific tissue using a non-invasive method. This review provides an overview of the current clinical protocols and preclinical experiments and results on how innovative drug development for boron delivery systems can also incorporate concurrent imaging. The last section focuses on the importance of proteomics for further optimization of BNCT, a highly precise and personalized therapeutic approach.

Naproxen release aspect from boron-doped carbon nanodots as a bifunctional agent in cancer therapy

In this present study, boron–carbon nanodots were synthesized by the hydrothermal method. Boron–carbon nanodots were prepared by varying the concentration ratios of boronic acid and citric acid: 1 : 25, 2 : 1, and 25 : 1, respectively. The precursors were then poured into a Teflon autoclave and heated at 240° for 4 h. This research aims to synthesise and evaluate the potential of boron–carbon nanodots as a bioimaging agent and naproxen delivery carrier. An X-ray diffractogram showed that the boron–carbon nanodots were amorphous. To analyse the functional groups, FTIR and XPS analysis was carried out. Spectrofluorometric analysis (λ_ex 320 nm) showed that the formulation of boron–carbon nanodots 2 : 1 (BCD 2 : 1) has the most ideal fluorescent properties at λ_em 453 nm, whereas UV-vis analysis showed λ_max at 223 nm, with a quantum yield of 52.29%. A confocal laser scanning micrograph and toxicity test (MTT assays) showed that boron–carbon nanodots delivered naproxen efficiently with loading amount and loading efficiency of naproxen 28% and 65%, respectively. Furthermore, it induced an anticancer effect in HeLa cells. This result indicated that boron–carbon nanodots can be used as a bioimaging agent and naproxen delivery carrier.

In this present study, boron–carbon nanodots were synthesized by the hydrothermal method.