Current hotspot and study trend of innate immunity in COVID-19: a bibliometric analysis from 2020 to 2022.

Background: Since the coronavirus disease 2019 (COVID-19) has spread throughout the world, many studies on innate immunity in COVID-19 have been published, and great progress has been achieved, while bibliometric analysis on hotspots and research trends in this field remains lacking. Methods: On 17 November 2022, articles and reviews on innate immunity in COVID-19 were recruited from the Web of Science Core Collection (WoSCC) database after papers irrelevant to COVID-19 were further excluded. The number of annual publications and the average citations per paper were analyzed by Microsoft Excel. Bibliometric analysis and visualization of the most prolific contributors and hotspots in the field were performed by VOSviewer and CiteSpace software. Results: There were 1,280 publications that met the search strategy on innate immunity in COVID-19 and were published from 1 January 2020 to 31 October 2022. Nine hundred thirteen articles and reviews were included in the final analysis. The USA had the highest number of publications (Np) at 276 and number of citations without self-citations (Nc) at 7,085, as well as an H-index of 42, which contributed 30.23% of the total publications, followed by China (Np: 135, Nc: 4,798, and H-index: 23) with 14.79% contribution. Regarding Np for authors, Netea, Mihai G. (Np: 7) from the Netherlands was the most productive author, followed by Joosten, Leo A. B. (Np: 6) and Lu, Kuo-Cheng (Np: 6). The Udice French Research Universities had the most publications (Np: 31, Nc: 2,071, H-index: 13), with an average citation number (ACN) at 67. The journal Frontiers in Immunology possessed the most publications (Np: 89, Nc: 1,097, ACN: 12.52). "Evasion" (strength 1.76, 2021-2022), "neutralizing antibody" (strength 1.76, 2021-2022), "messenger RNA" (strength 1.76, 2021-2022), "mitochondrial DNA" (strength 1.51, 2021-2022), "respiratory infection" (strength 1.51, 2021-2022), and "toll-like receptors" (strength 1.51, 2021-2022) were the emerging keywords in this field. Conclusion: The study on innate immunity in COVID-19 is a hot topic. The USA was the most productive and influential country in this field, followed by China. The journal with the most publications was Frontiers in Immunology. "Messenger RNA," "mitochondrial DNA," and "toll-like receptors" are the current hotspots and potential targets in future research.

High-intensity and moderate-intensity interval training in heart failure with preserved ejection fraction: A meta-analysis of randomized controlled trials.

BACKGROUND: Exercise training significantly improves cardiorespiratory fitness (CRF) in heart failure with reduced ejection fraction (HFrEF) patients, but high-intensity interval training (HIIT) is not superior to moderate-intensity interval training (MIIT). Whether HIIT is more beneficial than MIIT in patients with heart failure with preserved ejection fraction (HFpEF) remains unclear. METHODS: On August 29, 2021, we conducted a comprehensive computerized literature search of the Medline, EMBASE, Web of Science, and Cochrane databases using the following keywords: "HF or diastolic HF or HFpEF or HF with normal ejection fraction and exercise training or aerobic exercise or isometric exercises or physical activity or cardiac rehabilitation." Only randomized controlled trials (RCTs) reporting comparisons between HIIT and MIIT in HFpEF were included in the final analysis to maintain consistency and obtain robust pooled estimates. Methodological quality was assessed based on the ratings of individual biases. To generate an overall test statistic, the data were analyzed using the random-effects model for a generic inverse variance. Outcome measures were reported as an odds ratio, and confidence intervals (CIs) were set at 95%. The study followed PRISMA guidelines. RESULTS: This meta-analysis included only RCTs comparing the efficacy of HIIT and MIIT in HFpEF patients. This study included 150 patients from 3 RCTs. In the current pooled data analysis, HIIT significantly improves diastolic function measured by E/A ratio (WMD, 0.13; 95% CI, 0.03-0.23, P = .009). However, no significant change was observed in the diastolic function measured by E/e' ratio (WMD, 0.39; 95% CI, -2.40 to 3.18, P = .78), and CRF evaluated by both VO2 (mL/kg per min; WMD, -0.86; 95%CI, -5.27 to 3.55, P = .70) and VE/CO2 slope (WMD, 0.15; 95% CI, -10.24 to 10.53, P = .98), and systolic function (EF-WMD, -2.39; 95% CI, -12.16% to 7.38%, P = .63) between HIIT and MIIT in patients with HFpEF. CONCLUSION: In HFpEF patients, HIIT may be superior to MIIT in improving diastolic function, measured by E/A, but not CRF and left ventricular systolic function.

Emerging trends in sacubitril/valsartan research: A bibliometric analysis of the years 1995-2021.

BACKGROUND: Sacubitril/valsartan has been approved for the treatment of heart failure (HF) patients with reduced ejection fraction; since then, it gradually became a new star drug in the therapy of HF. Nevertheless, the effectiveness of sacubitril/valsartan remains under investigation. Thus far, only a few bibliometric studies have systematically analyzed the application of sacubitril/valsartan. METHODS: Publications on sacubitril/valsartan were retrieved from the Web of Science Core Collection on April 29, 2021. Data were analyzed using Microsoft Excel 2019 (Redmond, WA), VOS viewer (Redmond, WA), and Cite Space V (Drexel University, Philadelphia, PA). RESULTS: A total of 1309 publications on sacubitril/valsartan published from 1995 to 2021 were retrieved. The number of publications regarding sacubitril/valsartan increased sharply in the last 6 years (2015-2021), and American scholars authored >40% of those publications. Most were published in the European Journal of Heart Failure, the United States was the bellwether with a solid academic reputation in this area. Solomon published the highest number of related articles and was the most frequently cited author. "Heart failure" was the leading research hotspot. The keywords, "inflammation," "fibrosis," and "oxidative stress" appeared most recently as research fronts. CONCLUSIONS: Research attention should be focused on clinical trial outcomes. Considering its effectiveness in HF, the mechanisms and further applications of sacubitril/valsartan may become research hotspots in the future and should be closely examined.

Ticagrelor and the risk of infections during hospitalization in patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention.

BACKGROUND AND AIMS: Although ticagrelor exerts an antibacterial activity, its effect on infections in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI) is unclear. We aimed to assess whether ticagrelor and clopidogrel affect infections in these patients during hospitalization. METHODS: A total of 2116 consecutive patients with STEMI undergoing PCI were divided into the ticagrelor (n = 388) and clopidogrel (n = 1728) groups. The primary outcome was infection onset. Secondary outcomes were in-hospital all-cause death and major adverse cardiovascular and cerebrovascular events (MACCE). Propensity score analyses were conducted to test the robustness of the results. RESULTS: Infections developed in 327 (15.4%) patients. There was no significant difference in infection between both groups (ticagrelor vs. clopidogrel: 13.1% vs. 16.0%, p = 0.164). Patients in the ticagrelor group had lower rates of in-hospital all-cause death and MACCE than patients in the clopidogrel group. Multivariate logistic regression analysis determined that ticagrelor and clopidogrel had a similar preventive effect on infections during hospitalization (adjusted odds ratio [OR] = 1.20; 95% confidence interval [CI] = 0.80-1.78, p = 0.380). Compared to the patients treated with clopidogrel, patients treated with ticagrelor had a slightly lower risk of other outcomes, but no statistical difference. Propensity score analyses demonstrated similar results for infections and other outcomes. CONCLUSIONS: Compared with clopidogrel treatment, ticagrelor treatment did not significantly alter the risk of infections during hospitalization among STEMI patients undergoing PCI, but was associated with a slightly lower risk of in-hospital all-cause death and MACCE.

Aggregation-induced photoluminescence enhancement of protamine-templated gold nanoclusters for 1-hydroxypyrene detection using 9-hydroxyphenanthrene as a sensitizer.

In this study, we confirmed that protamine-templated gold nanoclusters (PRT-AuNCs) exhibit aggregation-induced emission properties (AIE-PRT-AuNCs). 1-Hydroxypyrene (1-OHPy) further induced the aggregation of AIE-PRT-AuNCs via hydrogen bonding and electrostatic and hydrophobic interactions, resulting in the aggregation-induced photoluminescence enhancement of AIE-PRT-AuNCs. 9-Hydroxyphenanthrene was able to decrease the background signal, thus increasing the sensitivity of the method. Based on these findings, a cost-effective, highly sensitive and selective strategy was proposed for the quantitative detection of 1-OHPy. This method displayed a wide linear range of 0.924 - 74.1 nmol/L with a low detection limit of 0.277 nmol/L, showing great potential for the monitoring of 1-OHPy in human urine. This strategy may provide a theoretical basis for future studies of the AIE properties of metal nanoclusters and their applications in the field of chemical and biological sensing.

Sensitive and selective assay of uranyl based on the aggregation induced fluorescent quenching of protamine capped gold nanoclusters.

The protamine capped gold nanoclusters (AuNCs@PRT) were synthesized by an one-pot approach, and utilized as a nanoprobe for highly sensitive and selective assay of U(VI) ions. The method is based on the aggregation induced fluorescent quenching of AuNCs@PRT by U(VI) ions. Under optimum conditions, the decrease of fluorescence intensity displayed a good linear correlation with the concentration of U(VI) ions ranging from 20.4 nM to 9.74 µM, with a detection limit of 6.1 nM. The relative standard deviations were 3.86%, 1.41% and 1.71% via 11 detections at concentrations of 40 nM, 0.40 µM and 4.0 µM of U(VI), respectively. The quenching mechanism was demonstrated to be due to the binding of U(VI) towards PRT to cause the aggregation of AuNCs@PRT rather than metal-metal interaction. The results suggest the potential application of this approach for monitoring the level of U(VI) in environmental samples.

Assay of 1-hydroxypyrene via aggregation-induced quenching of the fluorescence of protamine-modified gold nanoclusters and 9-hydroxyphenanthrene-based sensitization.

This work describes a method for the determination of 1-hydroxypyrene (OH-Py) via aggregation-induced quenching of the emission of protamine-coated gold nanoclusters using 9-hydroxyphenanthrene (OH-Phe) as a sensitizer to boost the emission efficiency of nanoprobe. Under optimum conditions, the drop in fluorescence intensity at excitation/emission wavelengths of 300/596 nm is proportional to the concentrations of OH-Py in the range from 1.0 to 65 nM. The relative standard deviations are 4.2, 2.4 and 1.9% (for n = 11) at concentration levels of 8.0, 32 and 48 nM of OH-Py, respectively. The detection limit is 0.3 nM which is much lower than that of some previously reported methods. The recoveries from urine samples spiked with OH-Py ranged between 94.4 and 98.8%. Graphical abstract 1-Hydroxypyrene (OH-Py) can trigger the aggregation of protamine-gold nanoclusters (PRT-AuNCs), resulting in the emission quenching of PRT-AuNCs. 9-Hydroxyphenanthrene (OH-Phe) can boost the emission efficiency of nanoprobe. Thereby, a highly sensitive assay of OH-Py was established.

A novel simple experimental model for low-osmolar contrast-induced acute kidney injury using different definitions based on the levels of serum creatinine and cystatin C.

BACKGROUND: It remained lack of a kind of contrast-induced acute kidney injury (CI-AKI) model which was widely used in clinical practice and comparable to CI-AKI in humans. METHODS: Fifty Sprague-Dawley rats were divided into five groups of 10 rats each: (1) sham group (normal saline [NS] + NS); (2) NS plus low osmolality contrast medium (CM15) (NS + CM15); (3) furosemide (FM) plus NS (FM + NS); (4) FM + CM10; and (5) FM + CM15.We measured the levels of serum creatinine (SCr), cystatin C (cys-C) and histopathological scores of kidney tissues. RESULTS: SCr level in the FM + CM15 group were significantly increased after CM exposure compared with baseline levels (32.9 ± 4.57 vs. 158.7 ± 14.48 µmol/L, p < 0.001). Minor changes were found about the SCr levels between the pre- and post-exposure CM or NS treatment in the other groups. Additionally, the cys-C levels after CM exposure were increased compared with pretreatment levels in the FM + CM15 group (0.08 ± 0.03 vs. 0.18 ± 0.05 mg/L, p < 0.001). Minor changes were noted in the FM + NS group before and after NS administration. Only rats in the FM + CM15 group developed CI-AKI with the definitions of SCr or cys-C. Comparing to the FM + NS group, the histopathological scores were significantly increased in the FM + CM15 group. CONCLUSIONS: A simple and reliable animal model for low osmolality contrast medium-induced AKI was established, which is similar to clinical CI-AKI based on different definitions for AKI.

Protamine-stabilized gold nanoclusters as a fluorescent nanoprobe for lead(II) via Pb(II)-Au(I) interaction.

The authors report on a one-pot approach for synthesizing highly fluorescent protamine-stabilized gold nanoclusters. These are shown to be a viable nanoprobe for selective and sensitive fluorometric determination of lead(II) via quenching of fluorescence via Pb(II)-Au(I) interaction. Under optimized conditions, fluorescence measured at excitation/emission peaks of 300/599 nm drops in the 80 nM-15 µM lead(II) concentration range. The detection limit is 24 nM, and relative standard deviations (for n = 11) at concentrations of 0.10, 4.0 and 15 µM are 1.6, 2.5 and 1.9%, respectively. The relative recoveries of added lead(II) in the water samples ranged from 97.9 ± 2.29% to 101.2 ± 1.83%. Graphical abstract Lead(II) ions are found to be able to selectively and sensitively quench the fluorescence of the protamine-gold nanoclusters (PRT-AuNCs). Thereby, an inexpensive, selective and sensitive lead(II) assay was established.

Protamine-gold nanoclusters as peroxidase mimics and the selective enhancement of their activity by mercury ions for highly sensitive colorimetric assay of Hg(II).

We certify that protamine-gold nanoclusters (PRT-AuNCs) synthesized by one-pot method exhibit peroxidase-like activity. The catalytic activity of PRT-AuNCs followed typical Michaelis-Menten kinetics and exhibited higher affinity to 3,3',5,5'-tetramethylbenzidine (TMB) as the substrate compared to that of natural horseradish peroxidase. Meanwhile, we found that Hg(II) could dramatically and selectively enhance the peroxidase-like activity of PRT-AuNCs, and the enhanced mechanism by Hg(II) was demonstrated to be generation of the cationic Au species and the partly oxidized Au species (Auδ+) by Hg2+-Au0/Au+ interaction. Based on this finding, quantitative determinations of Hg(II) via visual observation and absorption spectra were achieved. The proposed strategy displays high selectivity that arises from the strong aurophilic interaction of mercury towards gold. Moreover, the developed method is highly sensitive with a wide linear range and low detection limit of 1.16 nM. This strategy is not only helpful to develop effective nanomaterials-based artificial enzyme mimics but also irradiative to discover new applications of artificial mimic enzymes in bio-detection, medical diagnostics, and biotechnology. Graphical abstract Protamine-gold nanoclusters (PRT-AuNCs) synthesized by one-pot method exhibit peroxidase-like activity. Hg(II) can stimulate the peroxidase-like activity of PRT-AuNCs selectively, enhancing their ability to catalyze the chromogenic reaction of TMB by H2O2.

The 100 most-cited articles in Parkinson's disease.

BACKGROUND: Parkinson's disease (PD), the second most common neurodegenerative disease, has serious clinical effects. Research on PD is increasing, but the quantity and quality of this research have not been reported. METHODS: To analyze the most-cited articles on PD and provide information about developments in this field, we searched for articles in the Web of Science for the keyword "Parkinson*" in the title. We selected the 100 most-cited articles and evaluated information including citation number, publication time, journal, impact factor, authors, original country, institution of corresponding author, and study type. RESULTS: Citation numbers for the 100 most-cited articles ranged from 669 to 6902, with a median of 944. The 100 articles were published from 1967 to 2009, with most appearing between 1996 and 2000 (n = 24) and 2001 to 2005 (n = 27). The publications appeared in a total of 31 journals, led by Science with 15 and the New England Journal of Medicine (NEJM) with 13. The majority (84%) of the 100 most-cited articles had ≥ 3 authors. The articles originated from 14 countries, led by the USA (n = 44) and England (n = 17). Among the 100 most-cited articles, 24 were clinical studies, 54 were laboratory studies, 20 were reviews, and 2 were clinical guidelines. None of these articles originated from South America, Oceania, or Africa. CONCLUSIONS: The present study provides historical perspectives on the progress of PD research and highlights trends and academic achievements in this field.

Hyperthyroidism with dome-and-dart T wave: A case report: A care-compliant article.

RATIONALE: Dome-and-dart T waves (or bifid T waves) are a rare phenomenon in the surface electrocardiogram. These wave forms are mainly observed in patients with congenital heart disease such as atrial septal defect and ventricular septal defect. And hyperthyroidism who presented with an electrocardiogram that had dome-and-dart T waves in a precordial lead is never been reported. PATIENT CONCERNS: The patient presented with continuous tachycardia, palpitations, chest tightness, and headache for 4 days, and aggravated for 1 day. DIAGNOSES: Hyperthyroidism. INTERVENTIONS: Methimazole. OUTCOMES: All symptoms were alleviated. LESSONS: Dome-and-dart or bifid T waves have been reported in the conventional 12-lead electrocardiograms in some patients with congenital heart disease. The case illustrated here, to the best of our knowledge, dome-and-dart or bifid T waves may associate with hyperthyroidism patients.

The 100 most-cited articles on aortic dissection.

BACKGROUND: To identify and characterize the most frequently cited articles that have been published on aortic dissection. METHODS: A list of the 100 most frequently cited publications (T100) about aortic dissection was generated by performing a searching of the Science Citation Index--Expanded using "aortic dissection" as the search term. Basic information about the articles was recorded, including number of citations, journal title, journal impact factor, time since publication, first author's country, topic/subspecialty of the research, and publication type. RESULTS: We finally included 180 articles on aortic dissection, from which we identified the 100 most frequently cited articles (T100). The most frequently cited article received 1079 citations, while the least frequently cited article received 68 (mean140.5 citations per article). The T100 originated from 19 countries, with more than half of them originating from the USA (n = 97). The T100 articles were published from 1955 to 2013, with 79% published during the period 1990-2009. In addition, there were 40 different journals with Circulation having the most citations (n = 38). Regarding the article type, there were 21 basic and 140 clinical research articles, one meta-analysis, and 18 review articles. Reviews had the highest mean number of citations (mean 235.5 citations per article). CONCLUSIONS: Our study provides a historical perspective on the progress of dissection research, and helps to identify the quality of the work, the discoveries made, and the trends steering the studies.

Hundred top-cited articles focusing on acute kidney injury: a bibliometric analysis.

BACKGROUND: Acute kidney injury (AKI) is a major global health issue, associated with poor short-term and long-term outcomes. Research on AKI is increasing with numerous articles published. However, the quantity and quality of research production in the field of AKI is unclear. METHODS AND ANALYSIS: To analyse the characteristics of the most cited articles on AKI and to provide information about achievements and developments in AKI, we searched the Science Citation Index Expanded for citations of AKI articles. For the top 100 most frequently cited articles (T100), we evaluated the number of citations, publication time, province of origin, journal, impact factor, topic or subspecialty of the research, and publication type. RESULTS: The T100 articles ranged from a maximum of 1971 citations to a minimum of 215 citations (median 302 citations). T100 articles were published from 1951 to 2011, with most articles published in the 2000s (n=77), especially the 5-year period from 2002 to 2006 (n=51). The publications appeared in 30 journals, predominantly in the general medical journals, led by New England Journal of Medicine (n=17), followed by expert medical journals, led by the Journal of the American Society of Nephrology (n=16) and Kidney International (n=16). The majority (83.7%) of T100 articles were published by teams involving ≥3 authors. T100 articles originated from 15 countries, led by the USA (n=81) followed by Italy (n=9). Among the T100 articles, 69 were clinical research, 25 were basic science, 21 were reviews, 5 were meta-analyses and 3 were clinical guidelines. Most clinical articles (55%) included patients with any cause of AKI, followed by the specific causes of contrast-induced AKI (25%) and cardiac surgery-induced AKI (15%). CONCLUSIONS: This study provides a historical perspective on the scientific progress on AKI, and highlights areas of research requiring further investigations and developments.

An enzyme-free strategy for ultrasensitive detection of adenosine using a multipurpose aptamer probe and malachite green.

We report on an enzyme-free and label-free strategy for the ultrasensitive determination of adenosine. A novel multipurpose adenosine aptamer (MAAP) is designed, which serves as an effective target recognition probe and a capture probe for malachite green. In the presence of adenosine, the conformation of the MAAP is converted from a hairpin structure to a G-quadruplex. Upon addition of malachite green into this solution, a noticeable enhancement of resonance light scattering was observed. The signal response is directly proportional to the concentration of adenosine ranging from 75 pM to 2.2 nM with a detection limit of 23 pM, which was 100-10,000 folds lower than those obtained by previous reported methods. Moreover, this strategy has been applied successfully for detecting adenosine in human urine and blood samples, further proving its reliability. The mechanism of adenosine inducing MAAP to form a G-quadruplex was demonstrated by a series of control experiments. Such a MAAP probe can also be used to other strategies such as fluorescence or spectrophotometric ones. We suppose that this strategy can be expanded to develop a universal analytical platform for various target molecules in the biomedical field and clinical diagnosis.

The 100 most-cited articles on cardiovascular diseases from Mainland China.

BACKGROUND: China, as a rapidly developing country with the largest population of cardiologist in the world, has an increasing importance in the field of cardiology. However, the quantity and quality of research production in the field of cardiology is unclear. AIMS: To analyze the characteristics of the high-level articles published on cardiovascular diseases in Mainland China, and to provide information about achievements and development in cardiovascular research. METHODS: We searched the Science Citation Index Expanded for citations of cardiovascular articles originating in mainland China from 2004 to 2015. For the 100 most frequently cited articles (T100), we evaluated the number of citations, publication time, province of origin, journal, impact factor, topic or subspecialty of the research, and publication type. RESULTS: The most frequently cited article received 703 citations at the most, while 50 at the least (mean 91.6 citations per article). T100 originated from 16 provinces, the plurality (n = 34) being from the Beijing. Sixty-seven percent were published during 2006-2009. The publications were in 29 different journals of which Circulation published the most (n = 14). Leading general medical journals Journal of the American Medical Association (n = 1), Lancet (n = 0) and New England Journal of Medicine (n = 0) featured only 1 published article, despite their extremely high impact factors. Of the T100 articles, there were 50 basic researches, 44 clinical researches, 5 meta-analyses and 1 review article. Clinical researches had the highest mean citations (mean 102.6 citations per article). CONCLUSIONS: This study provides a historical perspective on the scientific progress, and the trends in cardiovascular medicine in Mainland China.

A novel strategy for dual-channel detection of metallothioneins and mercury based on the conformational switching of functional chimera aptamer.

A novel strategy for dual-channel detection of metallothioneins (MTs) and Hg(2+) has been proposed. In the absence of Hg(2+), the functional chimera aptamer (FCA) designed can form an intact G-quadruplex with flexibility, which was demonstrated to have peroxidase-like activities upon hemin binding. In the presence of Hg(2+), the formation of T-Hg(2+)-T complex results in the conformational switching of FCA, which lost the peroxidase-like activities and cannot catalyze the oxidation of ABTS by H2O2. Upon addition of MTs in this solution, MTs could interact with Hg(2+) to form a MTs-Hg(2+) complex, leading to the recovery of the G-quadruplex DNAzyme. The color and absorbance of the sensing system were also changed accordingly. In the optimizing condition, ΔA was directly proportional to the concentration ranging from 8.84 nM to 1.0 µM for Hg(2+), and 7.82 nM to 0.462 µM for MTs with the detection limits of 2.65 nM and 2.34 nM, respectively. The proposed dual-channel method avoids the label steps in common methods, and allows direct analysis of the samples without costly instruments, and is reliable, inexpensive and sensitive.

A colorimetric aptasensor for the highly sensitive detection of 8-hydroxy-2'-deoxyguanosine based on G-quadruplex-hemin DNAzyme.

A highly sensitive, low-cost colorimetric aptasensor was developed for the determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in human urine. The method is based on a conformational switching of the 8-OHdG aptamer to form a G-quadruplex structure in the presence of 8-OHdG. The resulting G-quadruplex assembles into a peroxidase-like DNAzyme with hemin, which effectively catalyzes the oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS(2-)) by H2O2 to ABTS(+), resulting in an increase in the absorption signal at 416nm along with a color change of the solution. The response signals linearly correlated with the concentration of 8-OHdG, ranging from 466pM to 247nM with a detection limit of 141pM. The relative standard deviation and the recovery were 1.97-3.47% (n=11) and 98.8-100.2%, respectively. The proposed method avoids the label and derivatization steps in common methods and allows direct analysis of the samples by the naked eye without costly instruments, which is reliable, inexpensive, and sensitive.

An ultrasensitive label-free assay of 8-hydroxy-2'-deoxyguanosine based on the conformational switching of aptamer.

We developed a highly sensitive label-free assay of 8-hydroxy-2'-deoxyguanosine (8-OHdG) using 8-OHdG-aptamer (Apt) as the recognition element. The Apt was adsorbed onto the surface of gold nanoparticles (AuNPs), which prevents them from aggregating under high-salt conditions. Upon addition of 8-OHdG, the conformation of the Apt changes to form a G-quadruplex structure, which leads to the aggregation of the AuNPs along with the increase of the resonance light scattering intensity. The mechanism of 8-OHdG that induces Apt to form G-quadruplexes structure was studied by circular dichroism. The response signals linearly correlated with the concentration of 8-OHdG ranging from 90.8pM to 14.1nM with a detection limit of 27.3pM, which is much lower than that obtained by other methods. This method does not need any label steps and sophisticated equipment. The application for detection of 8-OHdG in real samples further demonstrated its reliability. This strategy would be helpful for developing a universal analytical method by simply replacing corresponding aptamers for various target molecules.

Fluorescence quenching determination of metallothioneins using 8-hydroxyquinoline-5-sulphonic acid-Cd(II) chelate.

A novel method for the determination of metallothioneins (MTs) in urine was developed by fluorescence quenching strategy. The response signals linearly correlated with the concentration of MTs in the ranges of 3.12×10(-8)-1.23×10(-6) mol L(-1), and the limit of detection (LOD) was 9.36×10(-9) mol L(-1). The proposed method avoids the label and derivatization steps in common methods, and is reliable, inexpensive and sensitive. Furthermore, the interaction of MTs and 8-hydroxyquinoline-5-sulphonic acid (HQS)-Cd(II) chelate was investigated, and a static quenching mode was proposed to be primarily responsible for the fluorescence quenching event. It could provide a promising potential for the detection of the biomacromolecules which have no native fluorescence, and be benefit to extend the application of fluorescence strategy.