Paclitaxel-Loaded Biotinylated Fe2+-Doped Carbon Dot: Combination Therapy in Cancer Treatment

Oxidative stress induced paclitaxel-derived carbon dots inhibit glioblastoma proliferation and EMT process

Glioblastoma represents the most prevalent and deadly form of brain tumor with limited therapeutic drugs. The existence of the blood-brain barrier (BBB) hinders drugs permeate to the brain efficiently. Nowadays, nano-formulations, particularly carbon dots, have emerged as promising candidates for targeting and treating brain diseases. In this study, we report the synthesis of a novel carbon dots, PTX-CDs, using a one-step hydrothermal method with paclitaxel (PTX) as the precursor. PTX-CDs shows increased water solubility by about 1000 times in comparison with PTX. Moreover, PTX-CDs effectively penetrates the BBB and exerts significant anticancer effects. In detail, PTX-CDs accumulates in mitochondria of tumor cells without adding extra targeted molecules, resulting in the damage of mitochondrial membrane potential and increased reactive oxygen species (ROS) level. Transcriptome profiling revealed that PTX-CDs disturbs the cell-cycle by inducing arrest at the G2/M phase, thereby inhibiting cell proliferation. PTX-CDs further decreased cell invasion by inhibiting the epithelial-mesenchymal transition (EMT) process in glioblastoma cells. PTX-CDs significantly inhibited the growth of intracranial tumors in orthotopic glioblastoma mice model and prolonged the survival of tumor-bearing mice. This study presents a viable strategy to develop CDs-based therapeutic agent for glioblastoma using the conventional chemotherapeutic drugs.

Recent advances in biotin-based therapeutic agents for cancer therapy

Biotin receptors, as biomarkers for cancer cells, are overexpressed in various tumor types. Compared to other vitamin receptors, such as folate receptors and vitamin B12 receptors, biotin receptor-based targeting strategies exhibit superior specificity and broader potential in treating aggressive cancers, including ovarian cancer, leukemia, colon cancer, breast cancer, kidney cancer, and lung cancer. These strategies promote biotin transport via receptor-mediated endocytosis, which is triggered upon ligand binding. Biotin, as the ligand of the biotin receptor, can be conjugated to anti-cancer drugs to form targeted therapies that bind to receptors overexpressed on tumor cells, thus increasing drug uptake. Despite these advantages, many candidate drugs have progressed slowly and remain in the preclinical stage, impeding clinical translation. This is mainly due to the effects of various conjugation methods and drug formulations on their functionality and efficacy. Therefore, developing novel biotin-based therapeutics is crucial. The innovation of this strategy lies in its multifunctionality-researchers can use different conjugation methods to design and synthesize these drugs, enabling precise targeting of various tumor types while minimizing toxicity to normal cells. These drugs include small-molecule-biotin conjugates (SMBCs) and nano-biotin conjugates (NBCs). This dual-platform approach represents a significant advancement in targeted therapy, offering unprecedented flexibility in drug design and delivery. Compared to chemotherapy drugs and traditional delivery systems, biotin-based drugs with tumor-specific targeting demonstrate enhanced targeting, improved efficacy, and reduced toxicity. This review examines strategies and applications for enhancing the delivery of chemotherapy drugs to cancer cells, highlighting the need for high-quality conjugates and strategies. It not only summarizes the latest progress but also provides key insights into how this emerging field could revolutionize personalized cancer treatment, especially in the context of precision medicine. Additionally, it offers perspectives on future research directions in this field.

DON encapsulated carbon dot-vesicle conjugate in therapeutic intervention of lung adenocarcinoma by dual targeting of CD44 and SLC1A5

Lung adenocarcinoma, recognized as one of the most formidable malignancies with a dismal prognosis and low survival rates, poses a significant challenge in its treatment. This article delineates the design and development of a carbon dot-vesicle conjugate (HACD-TMAV) for efficient cytotoxicity towards lung cancer cells by target selective delivery of the glutamine inhibitor 6-diazo-5-oxo-L-norleucine (DON) within CD44-enriched A549 cancer cells. HACD-TMAV is composed of hyaluronic acid-based carbon dots (HACDs) and trimesic acid-based vesicles (TMAV), which are bound via electrostatic interactions. TMAVs are formed by positively charged trimesic acid-based amphiphiles through H-type aggregation in water. HACDs were synthesized through a one-step hydrothermal route. The blue-emitting HACD-TMAV conjugate demonstrated selective bioimaging in CD44-overexpressed A549 lung cancer cells due to specific ligand-receptor interactions between HA and CD44. HACD-TMAV exhibited notably improved DON loading efficiency compared to individual nano-vehicles. HACD-TMAV-DON exhibited remarkable (∼6.0-fold higher) cytotoxicity against CD44-overexpressing A549 cells compared to CD44- HepG2 cells and HEK 293 normal cells. Also, DON-loaded HACD-TMAV showed ∼2.0-fold higher cytotoxicity against A549 cells compared to individual carriers and ∼4.5-fold higher cytotoxicity than by DON. Furthermore, HACD-TMAV-DON induced a ∼3.5-fold reduction in the size of 3D tumor spheroids of A549 cells. The enhanced anticancer effectiveness was attributed to starvation of the A549 cells of glutamine by dual targeting of glutamine metabolism and solute linked carrier family 1 member A5 (SLC1A5) through HA-linked CD44-mediated targeted delivery of DON. This led to over-production of reactive oxygen species (ROS) that induced apoptosis of cancer cells through downregulation of the PI3K/AKT/mTOR signaling cascade.

Inherently targeted estradiol-derived carbon dots for selective killing of ER (+) breast cancer cells via oridonin-triggered p53 pathway activation

One of the most prevalent cancers globally is breast cancer and approximately two thirds of the breast cancers are hormone receptor positive with estrogen receptors (ER) being a prominent target. Notably, p53 that controls several cellular functions and prevents tumor formation, gets suppressed in breast cancers. Reactivation of p53 can lead to cell cycle arrest as well as apoptosis. Therefore, targeting the estrogen receptor for selective delivery of anticancer drugs that can reactivate p53 in ER (+) breast cancers can be a crucial method in breast cancer therapy. Herein, we have designed and developed estradiol-derived inherently targeted specific carbon dots (E2-CA-CD) from 17β-estradiol and citric acid following a solvothermal method. The synthesized carbon dots were characterized using spectroscopic and microscopic techniques. The water soluble, intrinsically fluorescent E2-CA-CD showed excellent biocompatibility in MCF-7, MDA-MB-231 as well as NIH3T3 cells and demonstrated target specific bioimaging in ER (+) MCF-7 cells due to the overexpressed ER receptors. Furthermore, oridonin, a well-known hydrophobic anticancer drug capable of upregulating the p53 pathway, was loaded on the carbon dots to increase its bioavailability. E2-CA-CD-Ori caused ∼2.2 times higher killing in ER (+) MCF-7 cells compared to ER (-) MDA-MB-231 cells and normal cells NIH3T3. Also, E2-CA-CD-Ori showed ∼3 fold better killing in MCF-7 cells compared to native oridonin. E2-CA-CD-Ori-induced killing of MCF-7 cells took place through the early to late apoptotic pathway along with the elevation of the intracellular ROS level. Importantly, E2-CA-CD-Ori triggered the activation of the p53 pathway in MCF-7 cells, which in turn induced apoptosis involving the upregulation of Bax and downregulation of Bcl-2 leading to the selective and efficient killing of ER (+) MCF-7 cells.

Clozapine-laden carbon dots delivered to the brain via an intranasal pathway: Synthesis, characterization, ex vivo, and in vivo studies

Clozapine, which is widely used to treat schizophrenia, shows low bioavailability due to poor solubility and high first-pass metabolism. The study aimed to design clozapine-loaded carbon dots (CDs) to enhance availability of the clozapine to the brain via intranasal pathway. The CDs were synthesized by pyrolysis of citric acid and urea at 200 °C by hydrothermal technique and characterized by photoluminescence, transmission electron microscopy (TEM), X-ray Photoelectron Spectrometer (XPS), and Fourier transform infrared spectrum (FTIR). The optimized clozapine-loaded CDs (CLZ-CDs-1:3-200) showed a quasi-spherical shape (9-12 nm) with stable blue fluorescence. The CDs showed high drug solubilization capacity (1.5 mg drug in 1 mg/ml CDs) with strong electrostatic interaction with clozapine (drug loading efficiency = 94.74%). The ex vivo release study performed using nasal goat mucosa showed sustained release of clozapine (43.89%) from CLZ-CDs-1:3-200 for 30 h. The ciliotoxicity study (histopathology) confirmed no toxicity to the nasal mucosal tissues using CDs. In the rat model (in vivo pharmacokinetic study), when CDs were administrated by the intranasal route, a significantly higher concentration of clozapine in the brain tissue (Cmax = 58.07 ± 5.36 μg/g and AUCt (µg/h*g) = 105.76 ± 12.31) was noted within a short time (tmax = 1 h) compared to clozapine suspension administered by intravenous route (Cmax = 20.99 ± 3.91 μg/g, AUC t (µg/h*g) = 56.89 ± 12.31, and tmax = 4 h). The high value of drug targeting efficiency (DTE, 486%) index and direct transport percentage (DTP, 58%) indicates the direct entry of clozapine-CDs in the brain via the olfactory route. In conclusion, designed CDs demonstrated a promising dosage form for targeted nose-to-brain delivery of clozapine for the effective treatment of schizophrenia.

Carbon Dots in Treatment of Pediatric Brain Tumors: Past, Present, and Future Directions

Pediatric brain tumors remain a significant source of morbidity and mortality. Though developments have been made in treating these malignancies, the blood-brain barrier, intra- and inter-tumoral heterogeneity, and therapeutic toxicity pose challenges to improving outcomes. Varying types of nanoparticles, including metallic, organic, and micellar molecules of varying structures and compositions, have been investigated as a potential therapy to circumvent some of these inherent challenges. Carbon dots (CDs) have recently gained popularity as a novel nanoparticle with theranostic properties. This carbon-based modality is highly modifiable, allowing for conjugation to drugs, as well as tumor-specific ligands in an effort to more effectively target cancerous cells and reduce peripheral toxicity. CDs are being studied pre-clinically. The ClinicalTrials.gov site was queried using the search terms: brain tumor and nanoparticle, liposome, micelle, dendrimer, quantum dot, or carbon dot. At the time of this review, 36 studies were found, 6 of which included pediatric patients. Two of the six studies investigated nanoparticle drug formulations, whereas the other four studies were on varying liposomal nanoparticle formulations for the treatment of pediatric brain tumors. Here, we reviewed the context of CDs within the broader realm of nanoparticles, their development, promising pre-clinical potential, and proposed future translational utility.

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.

Emerging metal doped carbon dots for promising theranostic applications

As a bridge between organic fluorophores and inorganic quantum dots, carbon dots (CDs) have been recognized as emerging nanotheranostics for biomedical applications owing to their distinctive merits such as superior optical properties, flexible modification, adjustable functionalities, and remarkable photoactive therapeutic outcome, etc. Compared to metal free CDs, the introduction of metal ion in CDs endowed metal-doped CDs (MCDs) with tunable optical properties and new intrinsic properties, thereby illustrating its different capabilities from metal-free CDs for bioimaging and therapy. This review aims to summarize the recent progress of photonic MCDs as emerging nanoagent for theranostic application such as disease-related diagnostic (involving biosensing and bioimaging) and cancer therapy. The challenges and potential development of MCDs in nanotheranostic fields are also discussed.

One step synthesis of ultra-high quantum yield fluorescent carbon dots for "on-off-on" detection of Hg2+ and biothiols

In this paper, the carbon dots (CDs) with strong blue fluorescence were synthesized through hydrothermal method, which using folic acid, ammonium citrate and ethylenediamine as precursors. The prepared CDs with a high absolute quantum yield of 81.94% and showed excellent stability in high concentration salt solution and different pH conditions. With the addition of Hg²⁺, the signal of CDs was selectively quenched. At the same time, the CDs-Hg²⁺ system could be recovered after the introduction of biothiols. Moreover, the fluorescence of CDs showed a good linear relationship with Hg²⁺ (1-15 µM), and the detection limit as low as 0.08 µM. In addition, the prepared CDs with low toxicity could be used to detect Hg²⁺ in living cells and actual water samples.