Graphene quantum dots from chemistry to applications

Graphene quantum dots (GQDs) have been widely studied in recent years due to its unique structure-related properties, such as optical, electrical and optoelectrical properties. GQDs are considered new kind of quantum dots (QDs), as they are chemically and physically stable because of its intrinsic inert carbon property. Furthermore, GQDs are environmentally friendly due to its non-toxic and biologically inert properties, which have attracted worldwide interests from academic and industry. In this review, a number of GQDs preparation methods, such as hydrothermal method, microwave-assisted hydrothermal method, soft-template method, liquid exfoliation method, metal-catalyzed method and electron beam lithography method etc., are summarized. Their structural, morphological, chemical composition, optical, electrical and optoelectrical properties have been characterized and studied. A variety of elemental dopant, such as nitrogen, sulphur, chlorine, fluorine and potassium etc., have been doped into GQDs to diversify the functions of the material. The control of its size and shape has been realized by means of preparation parameters, such as synthesis temperature, growth time, source concentration and catalyst etc. As far as energy level engineering is concerned, the elemental doping has shown an introduction of energy level in GQDs which may tune the optical, electrical and optoelectrical properties of the GQDs. The applications of GQDs in biological imaging, optoelectrical detectors, solar cells, light emitting diodes, fluorescent agent, photocatalysis, and lithium ion battery are described. GQD composites, having optimized contents and properties, are also discussed to extend the applications of GQDs. Basic physical and chemical parameters of GQDs are summarized by tables in this review, which will provide readers useful information

Development and Application of Transition Metal-Catalyzed C–C Bond Functionalization in Strained Rings

The following dissertation discusses the development and application of transition metal-catalyzed C–C bond functionalization in strained heterocycles. The first focus of this work will be directed toward the formation of unstrained, fused-ring saturated aza-cycles through C–H/C–C bond cleavage/functionalization. A further focus was directed toward the construction of medium-sized oxacycles through C–C bond formation/cleavage of cyclobutenol derivatives.Chapter 1. A C–H/C–C Functionalization Approach to N-Fused Heterocycles from Saturated AzacyclesOur efforts toward the synthesis of fused aza-cycles from unfunctionalized cyclic amines by leveraging the release of ring strain is described. Specifically, the C−H functionalization of azacycles is achieved by forming α-hydroxy-β-lactams from α-ketoamide precursors under mild, visible light conditions. Regioselective cleavage of a C–C bond in the β-lactams using a Rh-complex followed by a cascade reaction of decarbonylation, 1,4-addition to an electrophile, and aldol cyclization reactions led to N-fused bicycles.Chapter 2. Construction of Seven-Membered Oxacycles Using a Rh-catalyzed Cascade C–C formation/Cleavage of Cyclobutenol DerivativesA method for synthesizing seven-membered oxacycles through the molecular remodeling of four-membered cyclobutenols derived from the commercially available squaric acid by leveraging their inherent strain and enone moiety is described. Notably, the use of Xantphos type ligands and rhodium complexes facilitated access to versatile oxepane derivatives through sequential intermolecular oxa-Michael addition and intramolecular migratory insertion followed by a C–C cleavage event

Exploring the potential of Toxoplasma gondii in drug development and as a delivery system

Abstract Immune-mediated inflammatory diseases are various groups of conditions that result in immune system disorders and increased cancer risk. Despite the identification of causative cytokines and pathways, current clinical treatment for immune-mediated inflammatory diseases is limited. In addition, immune-mediated inflammatory disease treatment can increase the risk of cancer. Several previous studies have demonstrated that Toxoplasma gondii manipulates the immune response by inhibiting or stimulating cytokines, suggesting the potential for controlling and maintaining a balanced immune system. Additionally, T. gondii also has the unique characteristic of being a so-called “Trojan horse” bacterium that can be used as a drug delivery system to treat regions that have been resistant to previous drug delivery therapies. In this study, we reviewed the potential of T. gondii in drug development and as a delivery system through current research on inflammation-regulating mechanisms in immune-mediated inflammatory diseases

PINK1 and Parkin regulate IP3R-mediated ER calcium release

Abstract Although defects in intracellular calcium homeostasis are known to play a role in the pathogenesis of Parkinson’s disease (PD), the underlying molecular mechanisms remain unclear. Here, we show that loss of PTEN-induced kinase 1 (PINK1) and Parkin leads to dysregulation of inositol 1,4,5-trisphosphate receptor (IP3R) activity, robustly increasing ER calcium release. In addition, we identify that CDGSH iron sulfur domain 1 (CISD1, also known as mitoNEET) functions downstream of Parkin to directly control IP3R. Both genetic and pharmacologic suppression of CISD1 and its Drosophila homolog CISD (also known as Dosmit) restore the increased ER calcium release in PINK1 and Parkin null mammalian cells and flies, respectively, demonstrating the evolutionarily conserved regulatory mechanism of intracellular calcium homeostasis by the PINK1-Parkin pathway. More importantly, suppression of CISD in PINK1 and Parkin null flies rescues PD-related phenotypes including defective locomotor activity and dopaminergic neuronal degeneration. Based on these data, we propose that the regulation of ER calcium release by PINK1 and Parkin through CISD1 and IP3R is a feasible target for treating PD pathogenesis

Species-Specific Detection and Quantification of Erwinia pyrifoliae in Plants by a Direct SYBR Green Quantitative Real-Time PCR Assay

The present study describes a SYBR Green real-time quantitative (q) PCR assay to detect Erwinia pyrifoliae in plants. E. pyrifoliae, first described in South Korea, is a phytopathogenic bacterial species in the genus Erwinia. In particular, specific detection, quantitation, and identification of E. pyrifoliae is still challenging, as symptoms resulting from its colonization of Asian pear blossoms are very similar to those caused by E. amylovora. E. pyrifoliae has biochemical, phenotypic, and genetic properties similar to those of E. amylovora. Moreover, other Erwinia species, including E. tasmaniensis and E. billingiae, are also detected by currently available molecular methods and with traditional methods as well. Therefore, in this study, previously published genome sequences of the genera Erwinia and Pantoea were compared to exploit species-specific genes for use as improved qPCR targets to detect E. pyrifoliae. In silico analyses of the selected gene and designed primer sequences, in conjunction with bio-SYBR Green real-time qPCR, confirmed the robustness of this newly developed assay. Consequently, the bio-SYBR Green real-time qPCR-based protocols developed here can be used for rapid and specific detection of E. pyrifoliae. They will potentially simplify and facilitate diagnosis and monitoring of this pathogen and guide plant disease management. [Graphic: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

A case of celiac disease with neurologic manifestations misdiagnosed as amyotrophic lateral sclerosis

Celiac disease (CD) is an immune-mediated enteropathy and is a rare disease in Asia, including in Korea. However, the ingestion of wheat products, which can act as a precipitating factor of CD, has increased rapidly. CD is a common cause of malabsorption, but many patients can present with various atypical manifestations as first presented symptoms, including anemia, osteopenia, infertility, and neurological symptoms. Thus, making a diagnosis is challenging. We report a case of CD that mimicked amyotrophic lateral sclerosis (ALS). The patient was a sexagenary man with a history of progressive motor weakness for 2 years. He was highly suspected as having ALS. During evaluation of his neurological symptoms, esophagogastroduodenoscopy (EGD) was performed because he had experienced loose stools and weight loss for the previous 7 months. On EGD, the duodenal mucosa appeared smooth. A biopsy revealed severe lymphoplasma cell infiltration with flattened villi. His serum endomysial antibody (immunoglobulin A) titer was 1:160 (reference, <1:40). Finally, he was diagnosed as having CD, and a gluten-free diet was immediately begun. At a 4-month follow-up, his weight and the quality of his stool had improved gradually, and the neurological manifestations had not progressed

C-H/C-C Functionalization Approach to N-Fused Heterocycles from Saturated Azacycles.

Herein we report the synthesis of substituted indolizidines and related N-fused bicycles from simple saturated cyclic amines through sequential C-H and C-C bond functionalizations. Inspired by the Norrish-Yang Type II reaction, C-H functionalization of azacycles is achieved by forming α-hydroxy-β-lactams from precursor α-ketoamide derivatives under mild, visible light conditions. Selective cleavage of the distal C(sp2)-C(sp3) bond in α-hydroxy-β-lactams using a Rh-complex leads to α-acyl intermediates which undergo sequential Rh-catalyzed decarbonylation, 1,4-addition to an electrophile, and aldol cyclization, to afford N-fused bicycles including indolizidines. Computational studies provide mechanistic insight into the observed positional selectivity of C-C cleavage, which depends strongly on the groups bound to Rh trans to the phosphine ligand