Transferrin conjugated nontoxic carbon dots for doxorubicin delivery to target pediatric brain tumor cells

A carbon quantum dot–gold nanoparticle system as a probe for the inhibition and reactivation of acetylcholinesterase: detection of pesticides

In this work, fluorescence (FL) quenching (turn-off) and recovery (turn-on) of carbon quantum dots (CQDs) in the presence of dispersed and aggregated gold nanoparticles (AuNPs) was used as a probe for monitoring the inhibition and reactivation of acetylcholinesterase (AChE).

EDTA-bonded multi-connected carbon-dots and their Eu3+ complex: preparation and optical properties

EDTA-bonded multi-connected carbon-dots (EDTA–C-dots) were prepared from carbon dot precursors and complexed with Eu³⁺ to give Eu³⁺-coordinated EDTA-bonded multi-connected carbon dots (Eu–EDTA–C-dots). Whereas EDTA–C-dots were readily soluble in DMSO, Eu–EDTA–C-dots could not be easily dissolved in DMSO, water, or other common organic solvents. The newly prepared materials were thoroughly characterized. The X-ray diffraction results showed that no crystalline phase of Eu oxides (europium oxide or europium hydroxide) could be observed in Eu–EDTA–C-dots. The infrared and UV-Vis spectra showed that coordination with Eu³⁺ ions did not damage the structure of the EDTA–C-dots. It was found that EDTA could be easily grafted on the surface of carbon dots and EDTA had minimal influence on the photoluminescence of the carbon dot matrix. In contrast, the existence of Eu³⁺ ions strongly quenched the photoluminescence of Eu–EDTA–C-dots. The measured and fitted decay lifetime indicated that Eu–EDTA–C-dots possessed two photoluminescence decay processes, i.e., radiative recombination and non-radiative recombination.

EDTA-bonded multi-connected carbon-dots (EDTA–C-dots) were prepared from carbon dot precursors and complexed with Eu³⁺ to give Eu³⁺-coordinated EDTA-bonded multi-connected carbon dots (Eu–EDTA–C-dots).

Pluronic F127 self-assembled MoS2 nanocomposites as an effective glutathione responsive anticancer drug delivery system

In this study, bio-responsive polymeric MoS₂ nanocomposites were prepared for use as a drug carrier for cancer therapy. Herein, we report the synthesis and demonstrate the self-assembly of pluronic F127 (PF127) on a cystamine–glutathione–MoS₂ (CYS–GSH–MoS₂) system, which can be used for GSH-triggered drug release under biological reducing conditions. The reduction-sensitive disulfide bond containing CYS was incorporated between the amphiphilic copolymer PF127 and GSH–MoS₂ to achieve feasible drug release. Percent drug loading capacity and encapsulation efficiency were 51.3% and 56%, respectively. In addition, when the MoS₂–GSH–CYS–PF127 nanocomposite was incubated in a GSH environment, the morphology of the nanocomposite tended to change, ultimately leading to drug release. The drug-loaded PF127–CYS–GSH–MoS₂ polymeric nanocomposites efficiently released 52% of their drug content after 72 h of incubation in a GSH reduction environment. The HeLa cells treated with DOX loaded MoS₂–GSH–CYS–PF127 showed 38% toxicity at drug concentration of 40 μg, which indicated that the successfully released of drug from carrier and caused the cell death. Further, fluorescence microscopy images of HeLa cells revealed the potential behavior of the MoS₂–GSH–CYS–PF12 nanocomposite during the 2- and 4 h incubation periods; the nanocomposite was only found in the cytoplasm of HeLa cells. Interestingly, after 6 h of incubation, the drug was slowly released from the nanocomposite and could enter the nucleus as confirmed by fluorescence imaging of HeLa cells. Altogether, our synthesized PF127-coated MoS₂ nanocomposite could be effectively adopted in the near future as a GSH-sensitive drug carrier.

In this study, bio-responsive polymeric MoS₂ nanocomposites were prepared for use as a drug carrier for cancer therapy.

Transferrin receptors-targeting nanocarriers for efficient targeted delivery and transcytosis of drugs into the brain tumors: a review of recent advancements and emerging trends

Treatment of glioblastoma multiforme (GBM) is a predominant challenge in chemotherapy due to the existence of blood-brain barrier (BBB) which restricts delivery of chemotherapeutic agents to the brain together with the problem of drug penetration through hard parenchyma of the GBM. With the structural and mechanistic elucidation of the BBB under both physiological and pathological conditions, it is now viable to target central nervous system (CNS) disorders utilizing the presence of transferrin (Tf) receptors (TfRs). However, overexpression of these TfRs on the GBM cell surface can also help to avoid restrictions of GBM cells to deliver chemotherapeutic agents within the tumor. Therefore, targeting of TfR-mediated delivery could counteract drug delivery issues in GBM and create a delivery system that could cross the BBB effectively to utilize ligand-conjugated drug complexes through receptor-mediated transcytosis. Hence, approach towards successful delivery of antitumor agents to the gliomas has been making possible through targeting these overexpressed TfRs within the CNS and glioma cells. This review article presents a thorough analysis of current understanding on Tf-conjugated nanocarriers as efficient drug delivery system.

Recent Advances in Targeted Tumor Chemotherapy Based on Smart Nanomedicines

Efficacy and safety of chemotherapeutic drugs constitute two major criteria in tumor chemotherapy. Nanomedicines with tumor-targeted properties hold great promise for improving the efficacy and safety. To design targeted nanomedicines, the pathological characteristics of tumors are extensively and deeply excavated. Here, the rationale, principles, and advantages of exploiting these pathological characteristics to develop targeted nanoplatforms for tumor chemotherapy are discussed. Homotypic targeting with the ability of self-recognition to source tumors is reviewed individually. In the meanwhile, the limitations and perspective of these targeted nanomedicines are also discussed.

Mitochondria-targeted zirconium metal-organic frameworks for enhancing the efficacy of microwave thermal therapy against tumors

Although microwave (MW) thermal therapy has been widely studied for the treatment of tumors due to its less invasiveness, recurrence of tumors is still observed because of the relatively low bioavailability of MW sensitizers. For enhancing the bioavailability of MW sensitizers, triphenyl phosphate (TPP)-conjugated and doxorubicin (DOX)-loaded porous zirconium metal-organic framework nanocubes (ZrMOF NCs) modified with polyethylene glycol (PEG), ZrMOF-PEG-TPP@DOX NCs, were prepared as a MW sensitizer with mitochondrial-targeting ability. Moreover, the mitochondria are more susceptible to heat than the tumor tissues; this leads to improved tumor cell apoptosis. The results of this study indicate that ZrMOF NCs exhibit excellent heating effects due to the increased collisions of ions in the micropores of ZrMOFs under MW irradiation. In addition, ZrMOF-PEG-TPP@DOX NCs show preferential aggregation in the mitochondria, confirmed by confocal microscopy images. In vivo MW thermal therapeutic efficacy of ZrMOF-PEG-TPP@DOX NCs + MW is also better without recurrence during treatment than that of ZrMOF-PEG@DOX NCs + MW at a similar thermal therapeutic temperature; this reveals that the mitochondrial-targeting strategy can enhance the MW thermal therapeutic efficacy. This study provides a new biosafe MW sensitizer with mitochondrial-targeting ability for enhancing the efficacy of MW thermal therapy against tumors.

Nanomedicines for Pediatric Cancers

Chemotherapy protocols for childhood cancers are still problematic due to the high toxicity associated with chemotherapeutic agents and incorrect dosing regimens extrapolated from adults. Nanotechnology has demonstrated significant ability to reduce toxicity of anticancer compounds. Improvement in the therapeutic index of cytostatic drugs makes this strategy an alternative to common chemotherapy in adults. However, the lack of nanomedicines specifically for pediatric cancer care raises a medical conundrum. This review highlights the current state and progress of nanomedicine in pediatric cancer and discusses the real clinical challenges and opportunities.

A functional preservation strategy for the production of highly photoluminescent emerald carbon dots for lysosome targeting and lysosomal pH imaging

Lysosomes, which can be easily targeted by molecules with abundant amino groups, play critical roles in endocytosis, autophagy, and phagocytosis; thus, it is important to accurately characterize lysosomes, including lysosomal pH, in living cells to understand their physiological and pathological functions. Herein, a new type of highly photoluminescent (PL) emerald carbon dots (CDs) was easily prepared through a functional preservation strategy (FPS) by simply mixing p-benzoquinone and ethanediamine at room temperature. The as-prepared CDs possessed abundant amino groups preserved from ethanediamine owing to FPS, and they exhibited excellent photostability as compared to the commercial LysoTracker probes. Consequently, they actively targeted lysosomes to sensitively respond to lysosomal pH in vitro owing to their abundant amino groups and good hydrophilicity. Thus, we could successfully monitor lysosomal pH dynamics during apoptosis in live cells.

Strategies for Enhancing the Permeation of CNS-Active Drugs through the Blood-Brain Barrier: A Review

Background: The blood brain barrier (BBB) is a dynamic and functional structure which poses a vast challenge in the development of drugs acting on the central nervous system (CNS). While most substances are denied BBB crossing, selective penetration of substances mainly occurs through diffusion, carrier mediated transport, or receptor mediated transcytosis. Methods: Strategies in enhancing BBB penetration have been reviewed and summarized in accordance with their type of formulation. Highlights in monoclonal antibodies, peptide-vectors, nanoparticles, and simple prodrugs were included. Conclusion: Nanoparticles and simple prodrugs, for example, can be used for efficient BBB penetration through inhibition of efflux mechanisms, however, monoclonal antibodies are the most promising strategy in BBB penetration. Close follow-up of future development in this area should confirm our expectation.

Label-free fluorescence imaging of cytochrome c in living systems and anti-cancer drug screening with nitrogen doped carbon quantum dots

As an important biomarker for the early stage of apoptosis, cytochrome c (Cyt c) has been recognized as a key component of the intrinsic apoptotic pathway. Fluorescence imaging tools enabling detection of Cyt c in apoptotic signaling have been rarely explored, though they are critical for cell biology and clinical theranostics. Here, we designed a novel label-free N-doped carbon dot (N-doped CD)-based nanosensor that enables fluorescence activation imaging of Cyt c release in cell apoptosis. The inner filter effect of Cyt c towards N-doped CDs enabled quantitative Cyt c measurement. The nanosensor exhibited high sensitivity and selectivity, rapid response, good cell-membrane permeability and low cytotoxicity. All these features are favorable for in situ visualization of Cyt c for apoptosis research. Notably, the developed nanosensor was successfully applied to monitor intracellular release of Cyt c, and to visualize Cyt c in living zebrafish for the first time. Moreover, it also provided a viable platform for cell-based screening of apoptosis-inducing compounds. In virtue of these advantages and potential, the developed assay not only holds great significance for the better understanding of certain diseases at the cellular level, but also provides an invaluable platform for apoptotic studies and screening of anti-cancer drugs toward drug development.

Cancer Targeting and Drug Delivery Using Carbon-Based Quantum Dots and Nanotubes

Currently cancer treatment is in large part non-specific with respect to treatment. Medication is often harsh on patients, whereby they suffer several undesired side effects as a result. Carbon-based nanoparticles have attracted attention in recent years due to their ability to act as a platform for the attachment of several drugs and/or ligands. Relatively simple models are often used in cancer research, wherein carbon nanoparticles are conjugated to a ligand that is specific to an overexpressed receptor for imaging and drug delivery in cancer treatment. These carbon nanoparticles confer unique properties to the imaging or delivery vehicle due to their nontoxic nature and their high fluorescence qualities. Chief among the ongoing research within carbon-based nanoparticles emerge carbon dots (C-dots) and carbon nanotubes (CNTs). In this review, the aforementioned carbon nanoparticles will be discussed in their use within doxorubicin and gemcitabine based drug delivery vehicles, as well as the ligand-mediated receptor specific targeted therapy. Further directions of research in current field are also discussed.

Crossing the blood-brain barrier with nanoparticles

The blood-brain barrier (BBB) is one of the most essential protection mechanisms in the central nervous system (CNS). It selectively allows individual molecules such as small lipid-soluble molecules to pass through the capillary endothelial membrane while limiting the passage of pathogens or toxins. However, this protection mechanism is also a major obstacle during disease state since it dramatically hinders the drug delivery. In recent years, various tactics have been applied to assist drugs to cross the BBB including osmotic disruption of the BBB and chemical modification of prodrugs. Additionally, nanoparticles (NPs)-mediated drug delivery is emerging as an effective and non-invasive system to treat cerebral diseases. In this review, we will summarize and analyze the advances in the drug delivery across the BBB using various NPs in the last decade. The NPs will cover both traditional and novel nanocarriers. The traditional nanocarriers consist of poly(butylcyanoacrylate), poly(lactic-co-glycolic acid), poly(lactic acid) NPs, liposomes and inorganic systems. In the meanwhile, novel nanocarriers such as carbon quantum dots with their recent applications in drug delivery will also be introduced. In terms of significance, this review clearly depicts the BBB structure and comprehensively describes various NPs-mediated drug delivery systems according to different NPs species. Also, the BBB penetration mechanisms are concluded in general, emphasized and investigated in each drug delivery system.

Magnetofluorescent Carbon Quantum Dot Decorated Multiwalled Carbon Nanotubes for Dual-Modal Targeted Imaging in Chemo-Photothermal Synergistic Therapy

Magnetofluorescent nanoparticles with diagnostic and therapeutic functions show great promise in nanomedicine. Here, we report the magnetofluorescent carbon nanotubes (CNTs)/doxorubicin (DOX) nanocomposites and their functions act in synergetic chemo-photothermal synergistic therapy (Chemo/PTT) in cancer excision. Magnetofluorescent CNTs conjugated with a folic acid (FA-GdN@CQDs-MWCNTs) were targets for dual-modal fluorescence (FL)/magnetic resonance (MR) imaging. Experiments in vitro and in vivo identified FA-GdN@CQDs-MWCNTs with low toxicity, and good biocompatibility. Moreover, FA-GdN@CQDs-MWCNTs whose release can be fostered by pH and NIR light dual-stimuli had been proved to be available for loading DOX. Following nuclear translocations, FA-GdN@CQDs-MWCNTs were engineered to deliver DOX that targeted the nuclei. In vivo experiment indicates that the Chemo/PTT, as compared with the respective single treatment, can significantly control tumor growth. In addition, Chemo/PTT was not shown to render any appreciable toxicity. These findings suggest that the FA-GdN@CQDs-MWCNTs/DOX could function as a multifunctional platform for simultaneous FL/MR imaging, PTT therapy, and drug delivery.

Exploring the optimal ratio of d-glucose/l-aspartic acid for targeting carbon dots toward brain tumor cells

Targeting imaging to the desired site of action can increase the accuracy and effectiveness of diagnostic and treatment. In this work, a series of fluorescent carbon dots (CDs) were prepared by varying molar ratios of d-glucose (Glu) to l-aspartic acid (Asp). Their photophysical properties, morphologies and structures were investigated in detail. More important, the targeting ability was screened by confocal laser scanning microscopy and flow cytometry. The results indicate that CDs prepared from the optimal molar ratio of Glu/Asp (7:3) exhibit the highest targeting ability on C6 glioma cells. This work highlights the interplay of molecular design and corresponding functions, and open new possibility of developing state-of-art nanoparticles for biomedical applications.

Facile development of nanocomplex-in-nanoparticles for enhanced loading and selective delivery of doxorubicin to brain

Aim: Facile development of polysaccharides-based carrier system for efficient delivery of doxorubicin (DOX) to the brain. Methods: DOX was nanocomplexed with alginate (Alg) followed by incorporation into chitosan (Cs) nanomatrices. The resulting carriers were optimized to have a net positive charge improving their delivery across the blood–brain barrier. The optimum DOX-loaded nanosystem was targeted to brain tissue via loading into various nasal dosage forms. Results: The pH-dependent ionization of both DOX and Alg was found to have a significant effect on DOX entrapment efficiency which was improved from 4% at slightly acidic media to 85% using different pHs. The nasal dosage forms, especially the insert, delivered the loaded DOX mostly to the brain tissue with targeting efficiency reaching 480%. Conclusion: New intranasal carrier system was developed with efficient targeting of DOX to the brain. The carrier has potential to be used for delivery of other drugs acting on CNS.

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Carbon dots: promising biomaterials for bone-specific imaging and drug delivery

Bone-related diseases and dysfunctions are heavy burdens on our increasingly aged society. One important strategy to relieve this problem is through early detection and treatment of bone-related diseases. Towards this goal, there has been constant interest in developing novel bone-specific materials for imaging and drug delivery. Currently, however, materials that have high affinity and specificity towards bone are very limited. Carbon dots (C-dots) synthesized from carbon nanopowder bind to calcified bones in vivo with high affinity and specificity. In this study we show that bone binding is highly unique to a specific type of C-dot, and that this binding is non-toxic. Significantly, C-dots derived from other raw materials did not show any bone binding properties. These differences are attributed to the differences in surface chemistry of C-dot preparations, highlighting the heterogeneous nature of C-dots. Importantly, bone-binding by carbon nanopowder derived C-dots is not significantly altered by chemical functionalization of their surface. These unique properties indicate the potential applications of carbon nanopowder-derived C-dots as highly bone-specific bioimaging agents and drug carriers.

Ultrasmall and photostable nanotheranostic agents based on carbon quantum dots passivated with polyamine-containing organosilane molecules

In this work, we demonstrate that ultrasmall, photostable and multifunctional carbon quantum dots (or carbon dots, CDs) passivated with polyamine-containing organosilane molecules can realize simultaneous cell imaging and anticancer drug delivery. The presence of abundant surface amine groups makes these CDs be able to covalently link with the anticancer drug, doxorubicin (DOX), with an extremely high drug loading capacity (62.8%), while the surface hydroxyl groups ensure the good water-dispersibility of the CDs-DOX. Besides the use as a drug carrier, the fluorescent CDs also enable the dynamic tracing of the drug release process. When the CDs-DOX complexes were internalized by the human breast cancer cells (MCF-7), DOX could gradually detach from the surface of CDs and enter into the cell nucleus, while the CDs themselves still resided in the cytoplasm. In addition, the in vivo experiments showed that the CDs-DOX complexes exhibited a better tumor inhibition performance than free DOX molecules, which may be ascribed to the prolonged drug accumulation in tumor tissues. Furthermore, the as-synthesized CDs also exhibited negligible cytotoxicity/systemic side effects, and could successfully illuminate mammalian, bacterial and fungal cells, making them good candidates as not only drug delivery vehicles but also universal cell imaging reagents. The present work may have implications for the fabrication of functional carbon-based nanomaterials and foster the development of carbon dots as novel nanotheranostics for various biomedical applications.

iRGD-functionalized PEGylated nanoparticles for enhanced colon tumor accumulation and targeted drug delivery

AIM

To enhance the tumor accumulation and targeted drug delivery for colon cancer therapy, iRGD peptide was introduced to the surface of PEGylated camptothecin-loaded nanoparticles (NPs).

METHODS

Cellular uptake, targeting specificity, biodistribution and antitumor capacity were evaluated.

RESULTS

The functionalization of iRGD facilitated tumor accumulation and cellular uptake of NPs by Colon-26 cells. Furthermore, the resultant iRGD-PEG-NPs remarkably improved the therapeutic efficacy of camptothecin in vitro and in vivo by inducing a higher degree of tumor cell apoptosis compared with PEG-NPs.

CONCLUSION

iRGD-PEG-NP is a desired drug delivery system to facilitate the drug accumulation in orthotopic colon tumor tissues and further drug internalization by colon cancer cells.

Tumor-Targeted and Clearable Human Protein-Based MRI Nanoprobes

Biocompatibility, targeting, and clearance are key challenges in the design of new MRI contrast agents. Herein, we report on a tumor-targeting, gadolinium biomineralized human transferrin (Tf) protein-based nanoparticle (Gd@Tf NP) for MRI use. As compared to the conventionally used gadolinium chelates, the resultant Gd@Tf NPs possess outstanding chemical stability and exhibited superior longitudinal relaxation. More importantly, our MR images show that Gd@Tf indeed retained the natural tumor targeting ability and the subsequent tumor retrieval biofunctions of Tf. Thus, such Tf protein-based MR NPs integrate T1 signal amplification, precise tumor targeting, and systematic clearance capabilities. They offer a new approach to design biocompatible multifunctional MRI contrast agents for a wide range of clinical imaging and treatment applications.

Tumor-penetrating Peptide-integrated Thermally Sensitive Liposomal Doxorubicin Enhances Efficacy of Radiofrequency Ablation in Liver Tumors

Purpose To investigate the role of a tumor-penetrating peptide (internalizing CRGDRGPDC [iRGD])-integrated thermally sensitive liposomal (TSL) doxorubicin (DOX) in combination with radiofrequency (RF) ablation of liver tumors in an animal model. Materials and Methods Approval from the institutional animal care and use committee was obtained. Characterization of iRGD-TSL-DOX was performed in vitro. Next, H22 liver adenocarcinomas were implanted in 138 mice in vivo. The DOX accumulation and cell apoptosis of iRGD-TSL-DOX and TSL-DOX with or without RF were evaluated (n = 5) at different time points after treatment with quantitative analysis or pathologic staining. Mice bearing tumors were randomized into the following six groups (each group, eight mice): no treatment, iRGD-TSL-DOX, TSL-DOX, RF alone, RF ablation followed by TSL-DOX at 30 minutes (TSL-DOX combined with RF), and RF ablation followed by iRGD-TSL-DOX (iRGD-TSL-DOX combined with RF). Kaplan-Meier method was used to estimate the survival curves and log-rank test was used for comparison with statistical software. Results DOX encapsulation efficiency in iRGD-TSL-DOX was 97.5% ± 1.3 (standard deviation) with temperature-dependent drug release capability confirmed in vitro. In vivo, the iRGD-TSL-DOX group had overall higher DOX concentration in the tumor and had maximal difference at 24 hours compared with TSL-DOX group (2.7-fold). RF caused more intense cell apoptosis at 24 hours (median, 65% vs 21%, respectively; P < .001). For end-point survival, the iRGD-TSL-DOX combined with RF group had better survival (median, 32 days) than TSL-DOX combined with RF (median, 27 days; P = .035) or RF alone (median, 21 days; P < .001). Conclusion Conjugation to iRGD helped to improve intratumoral DOX accumulation and further enhanced the activity of TSL-DOX in RF ablation of liver tumors. ^© RSNA, 2017 Online supplemental material is available for this article.

Folic acid-conjugated carbon dots as green fluorescent probes based on cellular targeting imaging for recognizing cancer cells

Green fluorescent CDs using the natural product dandelion as a carbon source were covalently conjugated with folate to differentiate cancer cells from normal cells.

pH-Sensitive N-doped carbon dots–heparin and doxorubicin drug delivery system: preparation and anticancer research

In this study, doxorubicin (DOX) hydrochloride as a model drug, N-doped carbon dots as a drug carrier, and heparin as an auxiliary medicine were selected to design and prepare a multi-functional drug delivery system with pH-triggered drug release.

Facilely synthesized pH-responsive fluorescent polymer dots entrapping doped and coupled doxorubicin for nucleus-targeted chemotherapy

The combination of physical doping and chemical coupling can significantly enhance the drug loading/release efficiency and improve the effect of cancer treatment. Based on this strategy, PEG-Dox doped and coupled PFBT polymer dots were optimized as a nucleus-targeted drug delivery platform for tumor therapy.