62 research outputs found
Teratogenicity of Ochratoxin A and the Degradation Product, Ochratoxin α, in the Zebrafish (Danio rerio) Embryo Model of Vertebrate Development
Ochratoxins, and particularly ochratoxin A (OTA), are toxic fungal-derived contaminants of food and other agricultural products. Growing evidence supports the degradation of OTA by chemical, enzymatic and/or microbial means as a potential approach to remove this mycotoxin from food products. In particular, hydrolysis of OTA to ochratoxin α (OTα) and phenylalanine is the presumptive product of degradation in most cases. In the current study, we employed the zebrafish (Danio rerio) embryo, as a model of vertebrate development to evaluate, the teratogenicity of OTA and OTα. These studies show that OTA is potently active in the zebrafish embryo toxicity assay (ZETA), and that toxicity is both concentration- and time-dependent with discernible and quantifiable developmental toxicity observed at nanomolar concentrations. On the other hand, OTα had no significant effect on embryo development at all concentrations tested supporting a decreased toxicity of this degradation product. Taken together, these results suggest that ZETA is a useful, and highly sensitive, tool for evaluating OTA toxicity, as well as its degradation products, toward development of effective detoxification strategies. Specifically, the results obtained with ZETA, in the present study, further demonstrate the toxicity of OTA, and support its degradation via hydrolysis to OTα as an effective means of detoxification
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A deep investigation into the structure of carbon dots
Since their discovery, carbon dots (CDs) have been a promising nanomaterial in a variety of fields including nanomedicine. Despite their potential in this area, there are many obstacles to overcome for CDs to be approved for biomedical use. One major hindrance to CDs’ approval is related to their poorly defined structure. Herein a structural study of CDs is presented in order to rectify this shortcoming. The properties of three CDs which have significant promise in biomedical applications, black CDs (B-CDs), carbon nitride dots (CNDs), and yellow CDs (Y-CDs), are compared in order to develop a coherent structural model for each nanosystem. Absorption coefficients were measured for each system and this data gave insight on the level of disorder in each system. Furthermore, extensive structural characterization has been performed in order to derive structural information for each system. This data showed that B-CDs and CNDs are functionalized to a greater degree and are also more disordered and amorphous than Y-CDs. These techniques were used to develop a structural model consistent with the obtained data and what is known for carbonic nanostructures. These models can be used to analyze CD emission properties and to better understand the structure-property relationship in CDs
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A Proposed Model Explaining the Photophysical and Microscopic Properties of Carbon Dots
Carbon dots (CDs) are a new class of nanomaterial discovered at the beginning of the 21st century. They have been extensively researched since then due to their promising properties and potential applications. However, there remains a great deal which is unknown about CDs, including their physical structure and the mechanism by which they emit light. This lack of clarity hinders the future applications of CDs in promising areas such as nanomedicine and photocatalysis, so a detailed study is compelled. Herein contains such an examination. First, a comprehensive structural characterization of CDs is undertaken to develop structural models for three different preparations of CDs. Next, a detailed investigation of CDs’ optical properties is undertaken before and after oxidation and reduction. This data, in conjunction with the structural model, is used to propose a mechanism for CDs’ photoluminescence. The potential to prepare red emissive CDs through various methods is also explored. Finally, some of CDs promising applications are highlighted through a fundamental investigation of CDs’ ability to sense metal cations, development of an immunoassay, and the preparation of self-targeting CDs to cross the blood-brain barrier. It is hoped that these fundamental and applied studies will enable the use of CDs in diverse future applications.</p
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The use of nanotechnology to combat liver cancer: Progress and perspectives
Liver cancer is one of the most common cancers worldwide and is also one of the most difficult cancers to treat, resulting in almost one million deaths per year, and the danger of this cancer is compounded when the tumor is nonresectable. Hepatocellular carcinoma (HCC) is the most common type of liver cancer and has the third highest mortality rate worldwide. Considering the morbid statistics surrounding this cancer it is a popular research topic to target for better therapy practices. This review summarizes the role of nanotechnology in these endeavors. Nanoparticles (NPs) are a very broad class of material and many different kinds have been used to potentially combat liver cancer. Gold, silver, platinum, metal oxide, calcium, and selenium NPs as well as less common materials are all inorganic NPs that have been used as a therapeutic, carrier, or imaging agent in drug delivery systems (DDS) and these efforts are described. Carbon-based NPs, including polymeric, polysaccharide, and lipid NPs as well as carbon dots, have also been widely studied for this purpose and the role they play in DDS for the treatment of liver cancer is illustrated in this review. The multifunctional nature of many NPs described herein, allows these systems to display high anticancer activity in vitro and in vivo and highlights the advantage of and need for combinatorial therapy in treating this difficult cancer. These works are summarized, and future directions are presented for this promising field.
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Photoinduced Electron Transfer in Carbon Dots with Long-Wavelength Photoluminescence
Carbon
dots have often been studied to investigate their unique
optical properties such as excitation wavelength-independence emission.
Carbon dots have also been shown to undergo electron transfer in different
situations. This study endeavors to investigate the properties of
carbon dots’ photoluminescence and electron transfer. Herein,
the preparation and characterization of carbon dots which exhibit
long wavelength photoluminescence has been reported. These carbon
dots exhibit quenching when exposed to metal ions in proportion to
the reduction potential of the metal, which experimental evidence
has shown for the first time. This property of metal ion reduction
potential-dependent quenching has been studied to show the collisional
electron transfer from amine groups in carbon dots to the metal ions.
Therefore, the photoluminescence in these carbon dots is directly
related to organic functional groups on the surface of the carbon
dots
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Recent development of carbon quantum dots regarding their optical properties, photoluminescence mechanism, and core structure
Carbon quantum dots (CDs) are a relatively new class of carbon nanomaterials which have been studied very much in the last fifteen years to improve their already favorable properties. The optical properties of CDs have drawn particular interest as they display the unusual trait of excitation-dependent emission, as well as high fluorescence quantum yields (QY), long photoluminescence (PL) decay lifetimes, and photostability. These qualities naturally lead researchers to apply CDs in the field of imaging (particularly bio-imaging) and sensing. Since the amount of publications regarding CDs has been growing nearly exponentially in the last ten years, many improvements have been made in the optical properties of CDs such as QY and PL lifetime. However, a great deal of confusion remains regarding the PL mechanism of CDs as well as their structural properties. Therefore, presented in this review is a summary and discussion of the QYs and PL lifetimes reported in recent years. The effect of method as well as precursor has been evaluated and discussed appropriately. The current theories regarding the PL mechanism of CDs are discussed, with special attention to the concept of surface state-controlled PL. With this knowledge, the improvement of preparation and applications of CDs related to their optical properties will be easily accomplished. Further improvements can be made to CDs through the understanding of their structural and optical properties
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Carbon Dots: Diverse Preparation, Application, and Perspective in Surface Chemistry
Carbon dots (CDs) are a novel class of nanoparticles with excellent properties. The development of CDs involves versatile synthesis, characterization, and various applications. However, the importance of surface chemistry of CDs, especially in applications, is often underestimated. In fact, the study of the surface chemistry of CDs is of great significance in the explanation of the unique properties of CDs as well as the pursuit of potential applications. In this feature article, we do not only introduce the development of CDs in our group but also highlight their applications where surface chemistry plays a critical role
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Localized states in carbon dots: Structural and optical investigation of three systems with varying degrees of carbonization
Carbon dots (CDs) have been widely researched in recent years, mainly to investigate their potential in various applications such as drug delivery, photocatalysis, and sensing. However, understanding of their fundamental properties, including physical and electronic structure, has lagged behind their development in applied sciences. To address this, it is necessary to use novel methods which go beyond the current level of characterization in the literature. In this work, we utilize time of flight-secondary ion mass spectrometry (ToF-SIMS) to generate specific knowledge of the structural components of three CDs generated in our lab. This work revealed that black CDs (B-CDs) possess a highly carbonic structure with nitrogen and oxygen functionalization throughout the particle structure. Carbon nitride dots (CNDs) possess some of these same carbonic structures, but also show the presence of more organic structures which would be expected through a bottom-up approach. In terms of carbonization, CNDs lie between B-CDs and the third sample, yellow-CDs (Y-CDs). Y-CDs are believed to be almost completely polymeric/organic in structure and the groups detected through this mass analysis supports this idea. The structural information from ToF-SIMS is compared with other structural techniques. Additionally, the optical properties of CDs before and after oxidation and reduction are used to craft a proposed photoluminescence (PL) mechanism for each system. The analysis contained herein enables further understanding of the structure of these three samples, and the attained understanding of the surface structure is particularly important for future biomedical applications.
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Carbon Dots: A Future Blood–Brain Barrier Penetrating Nanomedicine and Drug Nanocarrier
Wei Zhang,1,* Ganesh Sigdel,1,* Keenan J Mintz,1 Elif S Seven,1 Yiqun Zhou,1 Chunyu Wang,2,3 Roger M Leblanc1 1Department of Chemistry, University of Miami, Coral Gables, FL, 33146, USA; 2Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA; 3Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA*These authors contributed equally to this workCorrespondence: Roger M Leblanc Email [email protected]: Drug delivery across the bloodâ\u80\u93brain barrier (BBB) is one of the biggest challenges in modern medicine due to the BBBâ\u80\u99s highly semipermeable property that limits most therapeutic agents of brain diseases to enter the central nervous system (CNS). In recent years, nanoparticles, especially carbon dots (CDs), exhibit many unprecedented applications for drug delivery. Several types of CDs and CD-ligand conjugates have been reported successfully penetrating the BBB, which shows a promising progress in the application of CD-based drug delivery system (DDS) for the treatment of CNS diseases. In this review, our discussion of CDs includes their classification, preparations, structures, properties, and applications for the treatment of neurodegenerative diseases, especially Alzheimerâ\u80\u99s disease (AD) and brain tumor. Moreover, abundant functional groups on the surface, especially amine and carboxyl groups, allow CDs to conjugate with diverse drugs as versatile drug nanocarriers. In addition, structure of the BBB is briefly described, and mechanisms for transporting various molecules across the BBB and other biological barriers are elucidated. Most importantly, recent developments in drug delivery with CDs as BBB-penetrating nanodrugs and drug nanocarriers to target CNS diseases especially Alzheimerâ\u80\u99s disease and brain tumor are summarized. Eventually, future prospects of the CD-based DDS are discussed in combination with the development of artificial intelligence and nanorobots.Keywords: carbon dots, bloodâ\u80\u93brain barrier, drug delivery, brain tumor, central nervous system disease
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Carbon Dots: A Future Blood–Brain Barrier Penetrating Nanomedicine and Drug Nanocarrier
Drug delivery across the blood–brain barrier (BBB) is one of the biggest challenges in modern medicine due to the BBB’s highly semipermeable property that limits most therapeutic agents of brain diseases to enter the central nervous system (CNS). In recent years, nanoparticles, especially carbon dots (CDs), exhibit many unprecedented applications for drug delivery. Several types of CDs and CD-ligand conjugates have been reported successfully penetrating the BBB, which shows a promising progress in the application of CD-based drug delivery system (DDS) for the treatment of CNS diseases. In this review, our discussion of CDs includes their classification, preparations, structures, properties, and applications for the treatment of neurodegenerative diseases, especially Alzheimer’s disease (AD) and brain tumor. Moreover, abundant functional groups on the surface, especially amine and carboxyl groups, allow CDs to conjugate with diverse drugs as versatile drug nanocarriers. In addition, structure of the BBB is briefly described, and mechanisms for transporting various molecules across the BBB and other biological barriers are elucidated. Most importantly, recent developments in drug delivery with CDs as BBB-penetrating nanodrugs and drug nanocarriers to target CNS diseases especially Alzheimer’s disease and brain tumor are summarized. Eventually, future prospects of the CD-based DDS are discussed in combination with the development of artificial intelligence and nanorobots
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