[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Despite the various synthesis methods to obtain carbon dots (CDs), the bottom-up methods are still the most widely administrated route to afford large-scale and low-cost synthesis. However, as CDs are developed with increasing reports involved in producing many CDs, the structure and property features have changed enormously compared with the first generation of CDs, raising classification concerns. To this end, a new classification of CDs, named carbonized polymer dots (CPDs), is summarized according to the analysis of structure and property features. Here, CPDs are revealed as an emerging class of CDs with distinctive polymer/carbon hybrid structures and properties. Furthermore, deep insights into the effects of synthesis on the structure/property features of CDs are provided. Herein, the synthesis methods of CDs are also summarized in detail, and the effects of synthesis conditions of the bottom-up methods in terms of the structures and properties of CPDs are discussed and analyzed comprehensively. Insights into formation process and nucleation mechanism of CPDs are also offered. Finally, a perspective of the future development of CDs is proposed with critical insights into facilitating their potential in various application fields.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201901316

Evolution and Synthesis of Carbon Dots: From Carbon Dots to Carbonized Polymer Dots

Nanomaterials have emerged as an amazing class of materials that consists of a broad spectrum of examples with at least one dimension in the range of 1 to 100 nm. Exceptionally high surface areas can be achieved through the rational design of nanomaterials. Nanomaterials can be produced with outstanding magnetic, electrical, optical, mechanical, and catalytic properties that are substantially different from their bulk counterparts. The nanomaterial properties can be tuned as desired via precisely controlling the size, shape, synthesis conditions, and appropriate functionalization. This review discusses a brief history of nanomaterials and their use throughout history to trigger advances in nanotechnology development. In particular, we describe and define various terms relating to nanomaterials. Various nanomaterial synthesis methods, including top-down and bottom-up approaches, are discussed. The unique features of nanomaterials are highlighted throughout the review. This review describes advances in nanomaterials, specifically fullerenes, carbon nanotubes, graphene, carbon quantum dots, nanodiamonds, carbon nanohorns, nanoporous materials, core–shell nanoparticles, silicene, antimonene, MXenes, 2D MOF nanosheets, boron nitride nanosheets, layered double hydroxides, and metal-based nanomaterials. Finally, we conclude by discussing challenges and future perspectives relating to nanomaterials.

/pdf/nanomaterials-a-review-of-synthesis-methods-properties-5ebdqaoboz.pdf

Nanomaterials: a review of synthesis methods, properties, recent progress, and challenges

Crossing the blood-brain barrier with nanoparticles

Heteroatom-doped porous carbon materials (HPCMs) have found extensive applications in adsorption/separation, organic catalysis, sensing, and energy conversion/storage. The judicious choice of carbon precursors is crucial for the manufacture of HPCMs with specific usages and maximization of their functions. In this regard, polymers as precursors have demonstrated great promise because of their versatile molecular and nanoscale structures, modulatable chemical composition, and rich processing techniques to generate textures that, in combination with proper solid-state chemistry, can be maintained throughout carbonization. This Review comprehensively surveys the progress in polymer-derived functional HPCMs in terms of how to produce and control their porosities, heteroatom doping effects, and morphologies and their related use. First, we summarize and discuss synthetic approaches, including hard and soft templating methods as well as direct synthesis strategies employing polymers to control the pores and/or heteroatoms in HPCMs. Second, we summarize the heteroatom doping effects on the thermal stability, electronic and optical properties, and surface chemistry of HPCMs. Specifically, the heteroatom doping effect, which involves both single-type heteroatom doping and codoping of two or more types of heteroatoms into the carbon network, is discussed. Considering the significance of the morphologies of HPCMs in their application spectrum, potential choices of suitable polymeric precursors and strategies to precisely regulate the morphologies of HPCMs are presented. Finally, we provide our perspective on how to predefine the structures of HPCMs by using polymers to realize their potential applications in the current fields of energy generation/conversion and environmental remediation. We believe that these analyses and deductions are valuable for a systematic understanding of polymer-derived carbon materials and will serve as a source of inspiration for the design of future HPCMs.

Polymer-Derived Heteroatom-Doped Porous Carbon Materials.

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.

Recent development of carbon quantum dots regarding their optical properties, photoluminescence mechanism, and core structure

Early diagnosis of diseases is of great importance because it increases the chance of a cure and significantly reduces treatment costs Thus, development of rapid, sensitive, and reliable biosensing techniques is essential for the benefits of human life and health As such, various nanomaterials have been explored to improve performance of biosensors, among which, carbon dots (CDs) have received enormous attention due to their excellent performance In this Review, the recent advancements of CD-based biosensors have been carefully summarized First, biosensors are classified according to their sensing strategies, and the role of CDs in these sensors is elaborated in detail Next, several typical CD-based biosensors (including CD-only, enzymatic, antigen-antibody, and nucleic acid biosensors) and their applications are fully discussed Last, advantages, challenges, and perspectives on the future trends of CD-based biosensors are highlighted

Recent Developments of Carbon Dots in Biosensing: A Review.

Most of the dual nano drug delivery systems fail to enter malignant brain tumors due to a lack of proper targeting systems and the size increase of the nanoparticles after drug conjugation. Therefore, a triple conjugated system was developed with carbon dots (C-dots), which have an average particle size of 1.5-1.7 nm. C-dots were conjugated with transferrin (the targeted ligand) and two anti-cancer drugs, epirubicin and temozolomide, to build the triple conjugated system in which the average particle size was increased only up to 3.5 nm. In vitro studies were performed with glioblastoma brain tumor cell lines SJGBM2, CHLA266, CHLA200 (pediatric) and U87 (adult). The efficacy of the triple conjugated system (dual drug conjugation along with transferrin) was compared to those of dual conjugated systems (single drug conjugation along with transferrin), non-transferrin C-dots-drugs, and free drug combinations. Transferrin conjugated samples displayed the lowest cell viability even at a lower concentration. Among the transferrin conjugated samples, the triple conjugated system (C-dots-trans-temo-epi (C-DT)) was more strongly cytotoxic to brain tumor cell lines than dual conjugated systems (C-dots-trans-temo (C-TT) and C-dots-trans-epi (C-ET)). C-DT increased the cytotoxicity to 86% in SJGBM2 at 0.01 μM while C-ET and C-TT reduced it only to 33 and 8%, respectively. Not only did triple conjugated C-DT increase the cytotoxicity, but also the two-drug combination in C-DT displayed a synergistic effect.

/pdf/triple-conjugated-carbon-dots-as-a-nano-drug-delivery-model-42icq2qwrc.pdf

Triple conjugated carbon dots as a nano-drug delivery model for glioblastoma brain tumors.

Carbon dots (CDs) were synthesized by a microwave-mediated method and separated by size exclusion chromatography into three different size fractions. There was no correlation of the size with photoluminescence (PL) emission wavelength, which shows that the PL mechanism is not quantum-size dependent. UV/vis absorption and diffuse reflectance spectroscopies showed that the light absorption properties as well as the band gap of the CDs changed with the size of the particle. The combination of FTIR and XPS measurements revealed the composition on the surface of each fraction. The three CDs fractions were separately used in the photocatalytic degradation of organic dyes under simulated sunlight irradiation. The catalytic activity of the as-prepared CDs was found to increase as the size of the particles decreased. Complete degradation of both rhodamine B (RhB) and methylene blue (MB) was achieved in 150 min by the 2-nm CDs. The scavenger studies showed that the holes and superoxide radicals are the main species involved in the photocatalytic degradation of the dye by the 2-nm CDs. These CDs displayed high stability in the degradation of organic dyes for multiple cycles. The 2-nm CDs displayed promising photocatalytic degradation of p-nitrophenol (PNP) . These results demonstrate for the first time the application of bare carbon dots in the degradation of environmental contaminants.

Yiqun Zhou

Papers

Crossing the blood-brain barrier with nanoparticles

Recent development of carbon quantum dots regarding their optical properties, photoluminescence mechanism, and core structure

Recent Developments of Carbon Dots in Biosensing: A Review.

Triple conjugated carbon dots as a nano-drug delivery model for glioblastoma brain tumors.

Size-Dependent Photocatalytic Activity of Carbon Dots with Surface-State Determined Photoluminescence.