Amino acid deprivation induces TXNIP expression by NRF2 downregulation.

Thioredoxin-interacting protein (TXNIP) is sensitive to oxidative stress and is involved in the pathogenesis of various metabolic, cardiovascular, and neurodegenerative disorders. Therefore, several studies have suggested that TXNIP is a promising therapeutic target for several diseases, particularly cancer and diabetes. However, the regulation of TXNIP expression under amino acid (AA)-restricted conditions is not well understood. In the present study, we demonstrated that TXNIP expression was promoted by the deprivation of AAs, especially arginine, glutamine, lysine, and methionine, in non-small cell lung cancer (NSCLC) cells. Interestingly, we determined that increased TXNIP expression induced by AA deprivation was associated with nuclear factor erythroid 2-related factor 2 (NRF2) downregulation, but not with activating transcription factor 4 (ATF4) activation. Furthermore, N-acetyl-l-cysteine (NAC), a scavenger of reactive oxygen species (ROS), suppressed TXNIP expression in NSCLC cells deprived of AA. Collectively, the induction of TXNIP expression by AA deprivation was mediated by ROS production, potentially through NRF2 downregulation. Our findings suggest that TXNIP expression may be associated with the redox homeostasis of AA metabolism and provide a possible rationale for a therapeutic strategy to treat cancer with AA restriction.

High Fructose Concentration Increases the Fluorescence Stability of DNA-Templated Copper Nanoclusters by Several Thousand Times.

DNA-templated copper nanoclusters (CuNCs) have limited applications because of their low fluorescence stability (several tens of minutes). In this study, we prepared CuNCs with improved temporal fluorescence stability by introducing fructose into the CuNC synthesis process and optimizing the reaction conditions. The inclusion of fructose increased the operating lifetime of CuNCs by approximately 5200-fold from 30 min to 108 days and improved their stability against heat, acids, and bases compared to CuNCs synthesized under original conditions. In addition, the fluorescence signal of CuNCs was maintained for a significantly longer time when stored at refrigeration (4 °C) and freezing (-20 °C) temperatures. Importantly, this method did not require the addition of substances other than fructose or any additional physicochemical treatment to maintain the fluorescence of DNA-templated CuNCs for more than several tens of days. As such, this study could serve as a basis to improve the stability of CuNCs for various applications.

The Effect of COVID-19 Outbreak and Incidence on the Health-Related Behaviors and Depression of Gyeongnam Residents in Republic of Korea.

Background and Objectives: This study aimed to investigate whether the occurrence of COVID-19 brought about changes in the health behaviors and depression levels of residents in Gyeongnam in Republic of Korea, and whether the prevalence of COVID-19 was related to differences in health behaviors and depression levels among different regions. Materials and Methods: The researchers utilized raw data from the 2019-2020 Community Health Survey in Gyeongnam and conducted analyses using SPSS 25.0. The study included a total of 35,880 participants from 18 cities and counties in the Gyeongnam region (17,942 participants in 2019 and 17,938 participants in 2020). Results: The results of the comparative analysis between pre- and post-COVID-19 occurrence showed that, after the occurrence of COVID-19, the smoking cessation rate and monthly alcohol consumption rate among current smokers decreased, while the high-risk drinking rate increased. The rate of physical activity (walking) increased, but the prevalence of depression experiences and depressive symptoms also increased. Furthermore, the comparative analysis between areas with a higher number of COVID-19 cases and those with a lower number of cases revealed that areas with a higher number of cases had higher monthly alcohol consumption rates, as well as a higher prevalence of depression experiences and depressive symptoms. Conclusions: Considering that the occurrence and severity of COVID-19 had significant impacts on the health behaviors and depression levels of residents in Gyeongnam, this highlights the need for active intervention and management by the national and local governments in response to the occurrence and management of infectious diseases, including COVID-19, to address the health status and health behaviors of the local population.

Knockdown of YAP/TAZ sensitizes tamoxifen-resistant MCF7 breast cancer cells.

Although endocrine therapy with tamoxifen has improved survival in breast cancer patients, resistance to this therapy remains one of the major causes of breast cancer mortality. In the present study, we found that the expression level of YAP/TAZ in tamoxifen-resistant MCF7 (MCF7-TR) breast cancer cells was significantly increased compared with that in MCF7 cells. Knockdown of YAP/TAZ with siRNA sensitized MCF7-TR cells to tamoxifen. Furthermore, siRNA targeting PSAT1, a downstream effector of YAP/TAZ, enhanced sensitivity to tamoxifen in MCF7-TR cells. Additionally, mTORC1 activity and survivin expression were significantly decreased during cell death induced by combination treatment with YAP/TAZ or PSAT1 siRNA and tamoxifen. In conclusion, targeting the YAP/TAZ-PSAT1 axis could sensitize tamoxifen-resistant MCF7 breast cancer cells by modulating the mTORC1-survivin axis.

Equipment-free, salt-mediated immobilization of nucleic acids for nucleic acid lateral flow assays.

As the world has been facing several deadly virus crises, including Zika virus disease, Ebola virus disease, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and Coronavirus disease 2019 (COVID-19), lateral flow assays (LFAs), which require minimal equipment for point-of-care of viral infectious diseases, are garnering much attention. Accordingly, there is an increasing demand to reduce the time and cost required for manufacturing LFAs. The current study introduces an equipment-free method of salt-mediated immobilization of nucleic acids (SAIoNs) for LFAs. Compared to general DNA immobilization methods such as streptavidin-biotin, UV-irradiation, and heat treatment, our method does not require special equipment (e.g., centrifuge, UV-crosslinker, heating device); therefore, it can be applied in a resource-limited environment with reduced production costs. The immobilization process was streamlined and completed within 30 min. Our method improved the color intensity signal approximately 14 times compared to the method without using SAIoNs and exhibited reproducibility with the long-term storage stability. The proposed method can be used to detect practical targets (e.g., SARS-CoV-2) and facilitates highly sensitive and selective detection of target nucleic acids with multiplexing capability and without any cross-reactivity. This novel immobilization strategy provides a basis for easily and inexpensively developing nucleic acid LFAs combined with various types of nucleic acid amplification.

Comparison of Factors Associated With Direct Versus Transferred-in Admission to Government-Designated Regional Centers Between Acute Ischemic Stroke and Myocardial Infarction in Korea.

BACKGROUND: There has been no comparison of the determinants of admission route between acute ischemic stroke (AIS) and acute myocardial infarction (AMI). We examined whether factors associated with direct versus transferred-in admission to regional cardiocerebrovascular centers (RCVCs) differed between AIS and AMI. METHODS: Using a nationwide RCVC registry, we identified consecutive patients presenting with AMI and AIS between July 2016 and December 2018. We explored factors associated with direct admission to RCVCs in patients with AIS and AMI and examined whether those associations differed between AIS and AMI, including interaction terms between each factor and disease type in multivariable models. To explore the influence of emergency medical service (EMS) paramedics on hospital selection, stratified analyses according to use of EMS were also performed. RESULTS: Among the 17,897 and 8,927 AIS and AMI patients, 66.6% and 48.2% were directly admitted to RCVCs, respectively. Multivariable analysis showed that previous coronary heart disease, prehospital awareness, higher education level, and EMS use increased the odds of direct admission to RCVCs, but the odds ratio (OR) was different between AIS and AMI (for the first 3 factors, AMI > AIS; for EMS use, AMI < AIS). EMS use was the single most important factor for both AIS and AMI (OR, 4.72 vs. 3.90). Hypertension and hyperlipidemia increased, while living alone decreased the odds of direct admission only in AMI; additionally, age (65-74 years), previous stroke, and presentation during non-working hours increased the odds only in AIS. EMS use weakened the associations between direct admission and most factors in both AIS and AMI. CONCLUSIONS: Various patient factors were differentially associated with direct admission to RCVCs between AIS and AMI. Public education for symptom awareness and use of EMS is essential in optimizing the transportation and hospitalization of patients with AMI and AIS.

DNA micelle-templated copper nanoclusters for fluorescent imaging of MUC1-positive cancer cells.

DNA micelles formed by hydrophobic, self-assembly of amphiphilic DNA monomers have enormous potential in biological imaging owing to its unique and programmable, three-dimensional nanostructure. Herein, we rationally design double-stranded DNA oligonucleotides with two cholesterols that can spontaneously form the lipid-mediated DNA micelles and generate the high fluorescence signal after the formation of DNA-templated copper nanoclusters (CuNCs). Furthermore, the DNA aptamer specific to MUC1 protein, aberrantly overexpressed on the surface of cancer cells, is attached to lipid-mediated DNA micelles to confer the selectivity towards the target cancer cells. With the well-defined DNA nanostructures, the cell membrane of MUC1-positive cancer cells are stained by CuNCs exhibiting an intense, red fluorescence signal, which are clearly distinguished from MUC1-negative cancer cells. This approach may not only expand the application scope of both DNA micells and CuNCs, especially in the area of cellular imaging, but also provides a basis for developing other types of DNA nanostructures to detect target biomarkers.

T7 Endonuclease I-mediated voltammetric detection of KRAS mutation coupled with horseradish peroxidase for signal amplification.

Rapid and selective sensing of KRAS gene mutation which plays a crucial role in the development of colorectal, pancreatic, and lung cancers is of great significance in the early diagnosis of cancers. In the current study, we developed a simple electrochemical biosensor by differential pulse voltammetry technique for the specific detection of KRAS mutation that uses the mismatch-specific cleavage activity of T7-Endonuclease I (T7EI) coupled with horseradish peroxidase (HRP) to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) substrate in the presence of hydrogen peroxide (H2O2). In addition, we synthesized the nanocomposite composed of multi-walled carbon nanotube/chitosan-ionic liquid/gold nanoparticles (MWCNT/Chit-IL/AuNPs) on screen-printed carbon electrode surface to increase the electrode surface area and electrochemical signal. In principle, T7E1 enzyme recognized and cleaved the mismatched site formed by the presence of KRAS gene mutation, removing 5'-biotin of capture probes and subsequently reducing the differential pulse voltammetry signal compared to wild-type KRAS gene. With this proposed strategy, a limit of detection of 11.89 fM was achieved with a broad linear relationship from 100 fM to 1 µM and discriminated 0.1% of mutant genes from the wild-type target genes. This confirms that the developed biosensor is a potential platform for the detection of mutations in early disease diagnosis.

Relationship between pressure ulcer risk and sarcopenia in patients with hip fractures.

OBJECTIVE: Pressure ulcer (PU) is a frequent complication of hip fractures. PUs can develop at any time after a hip fracture but most appear within 2-4 days after surgery. The purpose of this study was to investigate the association between hip fractures due to sarcopenia and the risk of PUs in patients with hip fracture. METHOD: Between March 2017 and March 2019, patients aged ≥65 years of age with hip fractures were included in this retrospective cohort study. PU risk assessment according to the Braden Scale was performed within the first few hours after arrival at hospital. Skeletal muscle mass index (SMI) and hand grip strength were evaluated for a diagnosis of sarcopenia. RESULTS: Of the 289 patients admitted to the study institution, 180 patients were finally enrolled in the study (129 females; 51 males). In male patients, as SMI increased, so too did the Braden Scale score, which was statistically significant (p=0.02). However, there was no statistically significant difference between SMIs and Braden Scale scores in female patients (p=0.304). In male patients, there was no statistically significant difference between hand grip strength and Braden Scale score (p=0.251). However, in female patients, as hand grip strength increased, so too did the Braden Scale score; this was also statistically significant (p=0.041). CONCLUSION: In this study, decreased muscle mass and muscle weakness in patients with hip fractures were associated with increased PU risk as measured by Braden Scale scores in both males and females.

Fluorescence resonance energy transfer using DNA-templated copper nanoparticles for ratiometric detection of microRNAs.

We examined the effectiveness of a ratiometric method using DNA-templated copper nanoparticles, which can function as a probe for fluorescence resonance energy transfer. This method in combination with PCR successfully detected the target microRNA, which corresponded well with the results obtained by quantitative reverse transcription PCR.

Nucleic acid lateral flow assay for simultaneous detection of hygiene indicator bacteria.

A simple and rapid polymerase chain reaction (PCR)-based lateral flow assay (LFA) was developed for multiplex detection of hygiene indicator bacteria. Specifically, new PCR primers were designed for accurately detecting Escherichia coli, coliform bacteria, and total bacteria, and the results obtained as a colorimetric signal (generated by the accumulation of gold nanoparticles at distinct test zones on flow strips) could be identified by the naked eye in <10 min after the completion of PCR. The proposed LFA system did not exhibit any cross-reactivities with 8 distinct bacterial strains and can detect down to 1 colony forming unit (CFU)/mL. Furthermore, three species of cultured bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) inoculated onto sterilized ham were successfully analyzed using the LFA system, which demonstrated that this system shows sufficient sensitivity and specificity for food hygiene monitoring. The speed and simplicity of this LFA make it suitable for use in the food industry as part of routine screening analysis.

Associations between the quality of life in sarcopenia measured with the SarQoL® and nutritional status.

BACKGROUND: The purpose of this study was to evaluate the relationship between nutritional status and health-related quality of life after adjusting for essential factors of muscle mass, calf circumference, grip strength, and the timed up and go (TUG) test for diagnosis of sarcopenia. METHODS: The subjects of this study were those who visited a health care center or a senior welfare center among the aged 65 years or older living in a community in two counties (Jinju, Sacheon), and the survey was conducted from April to August 2019. Among them, those with cardiovascular disease, cognitive disorder, or malignancy were excluded. To determine the nutritional status of the elderly subjects, a questionnaire-based screening tool called DETERMINE was used. Developed as a health-related quality of life tool for sarcopenia, the Sarcopenia-specific Quality of Life (SarQoL) questionnaire was used. For screening of sarcopenia, a rapid questionnaire based on self-reported information about falls, mobility, and strength known as the SARC-F questionnaire was used. Assessment of sarcopenia included skeletal muscle mass, calf circumference, grip strength, and the TUG test. RESULTS: A total of 324 elderly people living in rural villages who were able to move to senior and welfare centers was surveyed. As a result of evaluating the association between SarQoL and nutritional risk in elderly subjects, the association was statistically significant in the moderate-risk group (B = - 5.542, p = 0.001) and in the high-risk group (B = - 8.136, p < 0.001) in comparison to the low-risk group. Significant correlations were found in all seven domains of SarQoL, except the fear domain. CONCLUSIONS: This study confirms an association between quality of life dimensions surveyed by the SarQoL questionnaire and nutritional status in elderly subjects. Therefore, appropriate interventions are needed following brief evaluation of sarcopenia and nutritional deficiency among elderly people in communities.

Translation and validation of the Korean version of the Sarcopenia Quality of Life (SarQoL-K®) questionnaire and applicability with the SARC-F screening tool.

PURPOSE: The purpose of this paper was to translate and validate into the Korea language and setting the Sarcopenia Quality of Life (SarQoL®) questionnaire. METHODS: The participants consisted of 450 individuals in Namgaram-2 cohort who were followed up in 2019-2020. The study participants were divided into four groups: (1) SARC-F < 4, (2) SARC-F ≥ 4 and robust grip strength, (3) SARC-F ≥ 4, low grip strength, robust muscle mass, (4) SARC-F ≥ 4, low grip strength, and low muscle mass. To assess construct validity, population with sarcopenia-associated symptoms (SARC-F ≥ 4) apart from the Korean SarQoL (SarQoL-K®) completed the Korean versions of two generic questionnaires, the Short Form-36 and the EuroQoL 5-dimension. To validate the Korean SarQoL®, we assessed its validity (discriminative power, construct validity), reliability (internal consistency, test-retest reliability), and floor/ceiling effects. RESULTS: The SarQoL-K® questionnaire was translated without major difficulties. The mean SarQoL-K scores were 72.9 (95%, CI; 71.2-74.6) in SARC-F < 4, 54.6 (95%, CI; 50.7-58.3) in SARC-F ≥ 4 and robust grip strength, 47.0 (95%, CI; 43.8-50.1) in SARC-F ≥ 4, low grip strength, robust muscle mass, 46.6 (95%, CI; 43.0-50.1) in SARC-F ≥ 4, low grip strength, and low muscle mass. The results indicated good discriminative power across each four groups (p < 0.001), high internal consistency (Cronbach's alpha of 0.866), and excellent test-retest reliability (ICC = 0.977, 95% CI 0.975-0.979). No floor- or ceiling-effects were observed. CONCLUSIONS: This is the first study to confirm the reliability and validity of the Korean version of the SarQoL®. We demonstrated that the population with sarcopenia-associated symptoms (determined using the SARC-F questionnaire) has a lower quality of life.

Disability, Frailty and Depression in the community-dwelling older adults with Osteosarcopenia.

BACKGROUND: The purpose of this study was to investigate the prevalence of osteosarcopenia in the over 60-year-old community and to evaluate whether osteosarcopenia is associated with disability, frailty and depression. METHODS: This study was performed using the baseline data of Namgaram-2, among the 1010 surveyed subjects, 885 study subjects who were 60 years or older and had all necessary tests performed were selected. The Kaigo-Yobo checklist (frailty), World Health Organization Disability Assessment Schedule (WHODAS) and Geriatric Depression Scale-Short Form-Korean (GDSSF-K) were used. The Asian Working Group for Sarcopenia (AWGS 2019) were applied in this study. Osteopenia was measured using data from dual energy X-ray absorptiometry (DEXA) and osteopenia was diagnosed when the T-score was less than - 1.0. The study subjects were divided into four groups: the normal group, in which both sarcopenia and osteopenia were undiagnosed, osteopenia only, sarcopenia only and the osteosarcopenia group, which was diagnosed with both sarcopenia and osteopenia. RESULTS: Of the 885 subjects over 60 years old evaluated, the normal group comprised 34.0%, the only osteopenia group 33.7%, the only sarcopenia group 13.1%, and the osteosarcopenia group 19.2%. WHODAS (17.5, 95% CI: 14.8-20.1), Kaigo-Yobo (3.0, 95% CI: 2.6-3.4), and GDSSF mean score (4.6, 95% CI: 3.9-5.4) were statistically significantly higher in the osteosarcopenia group compared the other groups. Partial eta squared (ηp2) of WHODAS (0.199) and Kaigo-Yobo (0.148) values ​​according to Osteosarcopenia were large, and GDSSF (0.096) was medium CONCLUSIONS: Osteosarcopenia is a relatively common disease group in the older adults community that may cause deterioration of health outcomes. Therefore, when evaluating osteopenia or sarcopenia in the older adults, management of those in both disease groups should occur together.

The relationship between extracellular water-to-body water ratio and sarcopenia according to the newly revised Asian Working Group for Sarcopenia: 2019 Consensus Update.

OBJECTIVE: The purpose of this study was to evaluate the association between sarcopenia and extracellular water-to-total body water ratio (ECW/TBW), one of the results of bioimpedance that can be easily measured in communities, following the recent revision of the Asian Working Group for Sarcopenia. METHODS: This study data were extracted from the baseline data of Namgaram-2. Among the surveyed subjects, 885 persons aged 60 years or older were selected as study subjects. All surveys were conducted on a one-on-one interview basis; blood tests, physical function evaluations (hand grip strength, short physical performance battery; SPPB), and dual-energy X-ray absorptiometry (DEXA) and bioimpedance were also conducted. The Asian Working Group's revised definition of sarcopenia was applied. ECW/TBW was one of the results of bioimpedance this study. RESULTS: A high ECW/TBW was 1.63 times higher in the low grip strength group than in the robust group (P = 0.017) and was 2.13 times higher in the low SPPB group compared to the robust group (P < 0.001). ECW/TBW higher than 0.391 was 2.17 times more likely to occur in sarcopenic patients compared to the robust group (P < 0.001). In addition, ECW/TBW lower than 0.391 was 3.65 times more likely to occur in severely sarcopenic patients compared to the robust group (P = 0.002). CONCLUSION: The ECW/TBW may be one of the valid research tools to evaluate the strength and physical performance of the elderly. In addition, it is expected to be one of the effective indicators for tracking physical function under newly revised sarcopenia criteria.

Three-Way Junction-Induced Isothermal Amplification with High Signal-to-Background Ratio for Detection of Pathogenic Bacteria.

The consumption of water and food contaminated by pathogens is a major cause of numerous diseases and deaths globally. To control pathogen contamination and reduce the risk of illness, a system is required that can quickly detect and monitor target pathogens. We developed a simple and reproducible strategy, termed three-way junction (3WJ)-induced transcription amplification, to detect target nucleic acids by rationally combining 3WJ-induced isothermal amplification with a light-up RNA aptamer. In principle, the presence of the target nucleic acid generates a large number of light-up RNA aptamers (Spinach aptamers) through strand displacement and transcription amplification for 2 h at 37 °C. The resulting Spinach RNA aptamers specifically bind to fluorogens such as 3,5-difluoro-4-hydroxybenzylidene imidazolinone and emit a highly enhanced fluorescence signal, which is clearly distinguished from the signal emitted in the absence of the target nucleic acid. With the proposed strategy, concentrations of target nucleic acids selected from the genome of Salmonellaenterica serovar Typhi (S. Typhi) were quantitatively determined with high selectivity. In addition, the practical applicability of the method was demonstrated by performing spike-and-recovery experiments with S. Typhi in human serum.

Pyrophosphate-Enhanced Oxidase Activity of Cerium Oxide Nanoparticles for Colorimetric Detection of Nucleic Acids.

In recent years, cerium oxide (CeO2) nanoparticles (NPs) have drawn significant attention owing to their intrinsic enzyme mimetic properties, which make them powerful tools for biomolecular detection. In this work, we evaluated the effect of pyrophosphate (PPi) on the oxidase activity of CeO2 NPs. The presence of PPi was found to enhance the oxidase activity of CeO2 NPs, with enhanced colorimetric signals. This particular effect was then used for the colorimetric detection of target nucleic acids. Overall, the PPi-enhanced colorimetric signals of CeO2 NPs oxidase activity were suppressed by the presence of the target nucleic acids. Compared with previous studies using CeO2 NPs only, our proposed system significantly improved the signal change (ca. 200%), leading to more sensitive and reproducible colorimetric analysis of target nucleic acids. As a proof-of-concept study, the proposed system was successfully applied to the highly selective and sensitive detection of polymerase chain reaction products derived from Klebsiella pneumoniae. Our findings will benefit the rapid detection of nucleic acid biomarkers (e.g., pathogenic bacterial DNA or RNA) in point-of-care settings.

Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications.

In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

Advances in Exosome Analysis Methods with an Emphasis on Electrochemistry.

Exosomes, small extracellular vesicles, are released by various cell types. They are found in bodily fluids, including blood, urine, serum, and saliva, and play essential roles in intercellular communication. Exosomes contain various biomarkers, such as nucleic acids and proteins, that reflect the status of their parent cells. Since they influence tumorigenesis and metastasis in cancer patients, exosomes are excellent noninvasive potential indicators for early cancer detection. Aptamers with specific binding properties have distinct advantages over antibodies, making them effective versatile bioreceptors for the detection of exosome biomarkers. Here, we review various aptamer-based exosome detection approaches based on signaling methods, such as fluorescence, colorimetry, and chemiluminescence, focusing on electrochemical strategies that are easier, cost-effective, and more sensitive than others. Further, we discuss the clinical applications of electrochemical exosome analysis strategies as well as future research directions in this field.

Fluorescence nucleobase analogue-based strategy with high signal-to-noise ratio for ultrasensitive detection of food poisoning bacteria.

We developed a simple and ultrasensitive strategy for the identification of foodborne pathogens utilizing a fluorescent nucleobase analogue [2-aminopurine (2-AP)]-containing split G-quadruplex that binds blocker DNA. Compared to a previous strategy that did not use blocker DNA, this strategy showed a significant increase in the signal-to-noise ratio-by approximately 300%-owing to the displacement of the blocker DNA by the target DNA that induces the formation of an active G-quadruplex structure, thereby leading to a substantial increase in the 2-AP fluorescence signal. The proposed strategy was rationally combined with polymerase chain reaction, which resulted in the successful determination of genomic DNA (within the range of 10-106 copies) derived from the food poisoning bacterium Escherichia coli, with a limit of detection of 5.2 copies and high selectivity. In addition, the practical applicability of this method was demonstrated by analyzing E. coli-spiked lettuce samples.