Earticle

Over a decade, cellulose based nanomaterials were hot research topics even cellulose is most useful biomass component for many applications. Last a few years, we have started to explore lignin based nano particles. However, the utilization of hemicellulose (typically 5-carbon sugars) is still the bottleneck of the current biorefinery industry. In this presentation after introducing our research in cellulose nanofibers, I will give an overview of our recent efforts: 1). Introducing hot-water extraction at relatively low temperature (120–180ºC) as an efficient pre-treatment strategy for the extraction of hemicellulose sugars from biomass as part of biorefinery process; 2) To utilize hemicellulose sugar stream, an effective hot-water pre-extraction and carbonization strategy of lignocellulosic biomass was introduced to synthesized fluorescent carbon dots (CDs) with tunable photoluminescence (PL) intensity and quantum yields (QYs) without carbonization of the entire biomass. No additional doping agent was used according to an innovative bio-refinery concept. The yields of de-branched sugars in hot-water extractions can be adjusted with increasing temperature between 120–180 ºC, thereby leading to distinct N-doping CDs after high temperature carbonization (220 ºC for 5 h); 3) Processing cellulose and lignin solid into lignin contained cellulose nanofibers and demonstrating a few unique applications such as superhydrophobic coating, nanodiamonds.

We report the use of carrot, a new and inexpensive biomaterial source, for preparing high quality carbon dots (CDs) instead of semi-conductive quantum dots for bioimaging application. The as-derived CDs possessing down and up-conversion photoluminescence features were obtained from carrot juice by commonly used hydrothermal treatment. The corresponding physiochemical and optical properties were investigated by electron microscopy, fluorescent spectrometry, and other spectroscopic methods. The surfaces of obtained CDs were highly covered with hydroxyl groups and nitrogen groups without further modification. The quantum yield of as-obtained CDs was as high as 5.16%. The cell viability of HaCaT cells against a purified CD aqueous solution was higher than 85% even at higher concentration ($700{\mu}g\;mL^{-1}$) after 24 h incubation. Finally, CD cultured cells exhibited distinguished blue, green, and red colors, respectively, during in vitro imaging when excited by three wavelength lasers under a confocal microscope. Offering excellent optical properties, biocompatibility, low cytotoxicity, and good cellular imaging capability, the carrot juice derived CDs are a promising candidate for biomedical applications.

본 총설에서는 형광 특성 조절이 가능한 탄소점(carbon dots)을 중심으로 바이오메디컬 응용에 대한 최신 연구 동향을 다루고자 한다. 높은 광안정성과 우수한 생체 적합성을 가지는 탄소점은 합성 설계에 따라 형광 특성과 표면 작용기를 조절할 수 있어 차세대 형광 나노소재로 주목받고 있다. 먼저, 전구체와 합성 경로에 의존하여 탄소점의 화학적 및 구조적 특성에 미치는 영향을 논의하고, 이러한 차이가 형광 발광 특성에 미치는 영향을 발광 메커니즘 관점에서 살펴본다. 이어 바이오이미징, 측방 유동 분석을 포함한 바이오센싱, 약물 전달 및 광학적 치료 등 바이오메디컬 분야에서 보고된 대표적인 응용 사례를 소개한다. 또한 실제 시료 분석 및 응용 시의 한계와 이에 대한 대응 전략을 함께 논의하고자 한다. 마지막으로 기능성 탄소점 기반 바이오소재 연구의 향후 발전 방향과 가능성을 제시하고자 한다.

This mini-review aims to discuss recent research trends in biomedical applications, focusing on carbon dots with tunable fluorescence properties. Carbon dots, which possess high photostability and excellent biocompatibility, have attracted considerable attention as next-generation fluorescent nanomaterials due to their ability to control fluorescence characteristics and surface functional groups through synthetic design. First, we discuss how differences in precursors and synthetic pathways influence the chemical and structural properties of carbon dots and how these differences affect their photoluminescence characteristics from the perspective of emission mechanisms. Subsequently, representative applications reported in biomedical fields, including bioimaging, biosensing such as lateral flow assays, drug delivery, and phototherapy, are introduced. In addition, the limitations encountered in real sample analysis and practical applications, along with corresponding strategies to address them, are discussed. Finally, this review presents the future research directions and development potential of functional carbon dot-based biomaterials.