Electrochemical Detection of Nucleic Acids Using Three-Dimensional Graphene Screen-Printed Electrodes.

Electrochemical approaches, along with miniaturization of electrodes, are increasingly being employed to detect and quantify nucleic acid biomarkers. Miniaturization of the electrodes is achieved through the use of screen-printed electrodes (SPEs), which consist of one to a few dozen sets of electrodes, or by utilizing printed circuit boards. Electrode materials used in SPEs include glassy carbon (Chiang H-C, Wang Y, Zhang Q, Levon K, Biosensors (Basel) 9:2-11, 2019), platinum, carbon, and graphene (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). There are numerous modifications to the electrode surfaces as well (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). These approaches offer distinct advantages, primarily due to their demonstrated superior limit of detection without amplification. Using the SPEs and potentiostats, we can detect cells, proteins, DNA, and RNA concentrations in the nanomolar (nM) to attomolar (aM) range. The focus of this chapter is to describe the basic approach adopted for the use of SPEs for nucleic acid measurement.

High concordance between urine toxicology results and self-reported fentanyl use in Nevada and New Mexico.

BACKGROUND: Co-use of stimulants and opioids is often deliberate. However, the possibility remains that some people are unintentionally consuming fentanyl. To advance understanding of overdose risk, we examined the rate of concordance between self-reported fentanyl use and corresponding urine toxicology screen results. METHODS: Between August 2022-August 2023, 411 participants (adults who reported any non-medical drug use in the past three months) in Nevada and New Mexico completed a cross-sectional survey, of whom 64% (n = 270; the analytical sample) also completed a urine toxicology screen, which detects fentanyl use in the past three days. Positive predictive value, negative predictive value, sensitivity, and specificity were calculated using self-reported past three-day fentanyl use (yes/no) and urine toxicology screen results for the presence of fentanyl (positive/negative). RESULTS: Of the 270 participants who provided a urine sample, 268 are included in the descriptive statistics (two with inconclusive urine toxicology screen results were excluded). Of the 268 participants, 146 (54.5%) had a fentanyl-positive urine toxicology screen result, 122 (45.5%) had a fentanyl-negative urine toxicology screen result, 137 (51.1%) reported past three-day fentanyl use, and 130 (48.5%) reported no past three-day fentanyl use. Only 6.9% of those with a fentanyl-positive urine toxicology screen did not report recent fentanyl use. The sensitivity of self-reported fentanyl use was 93%, specificity was 97%, positive predictive value was 97%, and negative predictive value was 92%. DISCUSSION: The rate of unanticipated exposure to fentanyl (that is, positive urine screen and negative self-report) in this sample was low, at 6.9%. This runs counter to the national narrative that there is widespread unknown contamination of fentanyl in the drug supply. CONCLUSION: Future research is needed to further explore how people who use multiple substances interpret their overdose risk and what harm reduction methods they employ.

Risk of Hearing Loss in Neonates and Toddlers with in Utero Exposure to SARS-CoV-2.

OBJECTIVE: Given the prevalence of neonatal hearing loss (HL) associated with intrauterine viral exposures, the goal of this study is to provide information on neonatal HL in the context of the COVID-19 pandemic. METHODS: Data were drawn from the COVID-19 Mother Baby Outcomes (COMBO) Initiative. 1007 participants completed the newborn hearing screen as part of routine clinical care (COMBO-EHR cohort) and 555 completed the National Survey of Children's Health (NSCH) at 2 and/or 3 years of age for research purposes (COMBO-RSCH cohort). Maternal SARS-CoV-2 infection status during pregnancy was determined through electronic health records and maternal-reported questionnaires. RESULTS: In adjusted multivariate logistic regression models covarying for newborn age at assessment, mode of delivery, and gestational age at delivery, there was no significant association between intrauterine SARS-CoV-2 exposure and newborn hearing screening failure (OR = 1.05, 95% CI = 0.39-2.42, p = 0.91) in the COMBO-EHR cohort. In the COMBO-RSCH cohort, there were similar non-significant associations between intrauterine exposure to SARS-CoV-2 and maternal-reported concern for HL on the NSCH (OR = 1.19 [95% CI = 0.30-4.24], p = 0.79). CONCLUSION: There is no association between intrauterine exposure to SARS-CoV-2 and failed hearing screen in neonates. Similarly, based on the NSCH, there is no association between intrauterine exposure to SARS-CoV-2 and maternal-reported concern for hearing in toddlers. These results offer reassurance given the widespread nature of this pandemic with tens of millions of fetuses having a history of intrauterine exposure. LEVEL OF EVIDENCE: Level 4 Laryngoscope, 2024.

Association of electronic screen exposure with depression among women in early pregnancy: a cross-sectional study.

BACKGROUND: Previous studies indicated that excessive engagement in digital devices could lead to negative psychological impacts in general population. We aimed to determine the association of electronic screen exposure with depression among women in early pregnancy. METHODS: A cross-sectional study was conducted from June 2021 to June 2022. A total of 665 women in early pregnancy were recruited and the information included socio-demographic characteristics, screen exposure and Patient Health Questionnaire - 9 depression scale. RESULTS: Among the women in early pregnancy, the total daily smartphone viewing time was the longest (median [P25-P75], 5 [3-6] hours/day) in the three types of electronic screen exposure. The total daily smartphone viewing time (P = 0.015, OR[95%CI] = 1.09[1.11-1.18]), smartphone (P = 0.016, OR[95%CI] = 1.24[1.04-1.47]) and television viewing time (P = 0.006, OR[95%CI] = 1.35[1.09-1.67]) before nocturnal sleep were significantly associated with depression among women in early pregnancy. The thresholds calculated by receiver operator characteristic curves were 7.5 h/day, 1.5 h/day and 1.5 h/day, respectively. In addition, women with higher scores of smartphone addiction were more susceptible to depression (P<0.001, OR[95%CI] = 1.11[1.07-1.16]). The top three smartphone usages in women with depression were watching videos (22.0%), listening to music (20.9%) and playing games (16.7%). CONCLUSIONS: In conclusion, electronic screen exposure, including screen viewing time, smartphone addiction and problematic smartphone use was associated with depression among women in early pregnancy. Further studies are warranted to verify the conclusions.

Evaluation of hop tests based on Y-Balance test and FMS test outcomes in volleyball and basketball players to identify those prone to injury: a potential predictor of injury.

BACKGROUND: The quest for a reliable and effective method to identify athletes at risk of injury holds the promise of significantly reducing injury rates and improving overall athletic performance. This research delved into the relationship between the Functional Movement Screen (FMS), Y-Balance Test (YBT), and Hop tests (Side hop, Medial triple hop, and Lateral step-down hop), aiming to determine the potential in predicting injuries of hop tests among division 1 volleyball and basketball players. METHODS: This research was conducted with fifty-two participants from the Division 1 league, encompassing both volleyball and basketball players. The study rigorously employed the Functional Movement Screen (FMS), the Y-Balance Test (YBT), and various hop tests (side hop test, medial triple hop test, lateral step-down hop) to measure relevant variables. The data analysis used logistic regression, ensuring a comprehensive approach to the study. RESULTS: Results showed no significant relationship between FMS and Hop test for predicting injuries, but there was a relationship between ΔY and side hop that shows side hop test can predict injury, but there was no relationship between Lateral step down, Medial triple hop, and ΔY. CONCLUSIONS: Based on our findings, side hop, despite the medial triple hop and lateral step-down test, can be used as a sports injury predictor.

FL118: A potential bladder cancer therapeutic compound targeting H2A.X identified through library screening.

The treatment of bladder cancer is limited by low drug efficacy and drug resistance. Hence, this study aimed to screen and identify potential drug precursors and investigate their mechanism of action. A set of camptothecin derivatives showing high anti-tumor potential was selected from early-stage research or literature and synthesized to construct a compound library. A total of 135 compounds were screened in T24 and J82 cells, revealing that FL118 significantly inhibited the proliferation of GC (gemcitabine + cisplatin)-sensitive/insensitive cells. FL118 exhibited excellent penetration and killing ability in organoids and three GC-insensitive patient-derived xenografts. Chemical proteomic and docking calculations were employed to identify binding proteins, indicating that FL118 can bind into H2A.X and its entwined DNA. The results of Cellular thermal shift assay and surface plasmon resonance (Kd = 3.77E-6) support the above findings. Fluorescence localization revealed widespread binding of FL118 within the cell nucleus. Furthermore, WB showed that FL118 increased cellular DNA damage, resulting in significant cell cycle inhibition. The binding of FL118 to H2A.X hindered the damage repair process, leading to apoptosis. Controllable adverse reactions were observed in mice treated with FL118. In conclusion, FL118 may be a superior anti-bladder cancer compound that acts as a molecular glue binding to both H2A.X and DNA. The resistance mediated by the DNA damage repair to DNA damage caused by GC regimen can be reversed by FL118. This distinct mechanism of FL118 has the potential to complement existing mainstream treatment approaches for bladder cancer.

Proportion, Correlates and the Associations of Meeting 24-h Movement Guidelines With Mental Well-Being and Psychological Distress: A Cross-Sectional Study of 10 589 Chinese Students.

BACKGROUND: The increased trends in psychological distress and mental illness have been of great significance in public health concerns. The study aimed to investigate the proportion and correlates of meeting 24-h movement guidelines (including moderate to vigorous physical activity, screen time and sleep duration) and the associations between 24-h movement guidelines met and mental well-being and psychological distress in a large sample of Chinese students. METHODS: All participants received a physical examination and filled out questionnaires in this study. Chi-square tests were used to analyse the proportion of reaching 24-h guidelines by gender and logistic regression was used to analyse correlates of meeting 24-h guidelines. Two binary logistic regression models were used to analyse the association between meeting 24-h guidelines and mental well-being and psychological distress. The back-propagation artificial neural network was used to describe the importance of the independent variables. RESULTS: The findings revealed a generally low rate of meeting the 24-h movement guidelines, particularly concerning moderate to vigorous physical activity (16.5%). Meeting all three guidelines was related to better mental health in both boys and girls. Particularly, meeting screen time guideline and meeting sleep duration guideline appeared to be more important on mental outcomes, compared to meeting moderate to vigorous physical activity guideline. Compared with boys, girls were more susceptible to the influences of 24-h movement guidelines on mental health. CONCLUSIONS: Meeting all three components of the 24-h movement guidelines was associated with the most favourable mental health outcomes for both boys and girls. Thus, maintaining a daily balance of sufficient physical activity, limited screen time, and adequate sleep is crucial for enhancing the mental health status of students.

Dynamic convergence of autism disorder risk genes across neurodevelopment.

Over a hundred risk genes underlie risk for autism spectrum disorder (ASD) but the extent to which they converge on shared downstream targets to increase ASD risk is unknown. To test the hypothesis that cellular context impacts the nature of convergence, here we apply a pooled CRISPR approach to target 29 ASD loss-of-function genes in human induced pluripotent stem cell (hiPSC)-derived neural progenitor cells, glutamatergic neurons, and GABAergic neurons. Two distinct approaches (gene-level and network-level analyses) demonstrate that convergence is greatest in mature glutamatergic neurons. Convergent effects are dynamic, varying in strength, composition, and biological role between cell types, increasing with functional similarity of the ASD genes examined, and driven by cell-type-specific gene co-expression patterns. Stratification of ASD genes yield targeted drug predictions capable of reversing gene-specific convergent signatures in human cells and ASD-related behaviors in zebrafish. Altogether, convergent networks downstream of ASD risk genes represent novel points of individualized therapeutic intervention.

Neighborhood environments underpin screen time intervention success in children: Evidence from a study of greenspace and community programming across 130 US communities.

The goal of this study was to understand how neighborhood greenspace access may support or hinder the effectiveness of community programs and policies (CPPs) aimed at reducing racial and ethnic inequities in screen time among 4598 US children. We found higher CPP intensity was significantly associated with fewer screen time behaviors in high greenspace neighborhoods, but not neighborhoods with low or moderate greenspace. Moreover, there were significant differences in greenspace access by neighborhood-level race and ethnicity. Implementing CPPs without regard for racial and ethnic greenspace inequities may be an underlying cause in the perpetuation of inequities in childhood screen time.

Factors Associated With Screen Time Among Preschool Children in Lima, Peru.

OBJECTIVE: This study aims to identify factors associated with excessive screen time among preschoolers in Lima, Peru. METHODS: Cross-sectional analysis from a 2019 panel study in Lima, Peru, was conducted focusing on women, aged 18 and above, who are mothers of 3- to 5-year-olds in mid-high and mid-low districts. There were two outcome variables: excessive TV and excessive electronic devices screen time, defined as ≥ 1 h of screen exposure for each one. Explored factors included the mother's age, education and wealth index and the children's age, sex, physical activity, day care attendance and ultra-processed food consumption. Crude (cPR) and adjusted prevalence ratios (aPR) were estimated for the association between associated factors and excessive screen time using the GLM Poisson of with a logarithmic link. RESULTS: Excessive TV screen time and electronic devices prevalence was 74% and 36.9%, respectively. For TV screen time, a high wealth index (aPR 1.13; 95%CI: 1.03-1.23) and children's age (aPR 1.18; 95%CI: 1.08-1.29 for 4 years, PR = 1.17; 95%CI: 1.07-1.28 for 5 years) were significant. For electronic devices, significant associations included mothers with more than 3 children (aPR 0.77; 95%CI: 0.62-0.96), being single (aPR 1.27; 95%CI: 1.01-1.58) and a high wealth index (aPR 1.38; 95%CI: 1.13-1.68). Furthermore, significant associations were found between excessive electronic device screen time and consumption of candies and chocolates (aPR 1.38; 95%CI: 1.08-1.77). CONCLUSIONS: Seven out of 10 preschool children exceeded the recommended television screen time. Certain characteristics of the children, their mothers and the family's socio-economic situation are related to excessive television screen time and excessive electronic device screen time.

Electronic device usage among preschool children and its association with mental health status in Saudi Arabian kindergartens.

OBJECTIVES: To estimate the prevalence of electronic device usage and its association with mental health status among preschool children aged 3-6 years. METHODS: A cross-sectional study was conducted among preschool children aged 3-6 years in kindergartens in Makkah city in 2023-2024, using an electronic questionnaire. An Arabic version of the Strengths and Difficulties Questionnaire was used to assess mental health. RESULTS: We recruited a total of 399 children. The prevalence of electronic device usage was 91.5%. The number of hours spent using electronic devices ranged from 0 to 12 hour (h)/day, with a mean of 3.1 h/day. We found a significant positive correlation between the number of hours spent using electronic devices and emotional problems (r=0.200, p<0.001), conduct problems (r=0.149, p=0.003), hyperactivity (r=0.279, p<0.001), peer problems (r=0.104, p=0.038), and total difficulty scores (r=0.263, p<0.001). We also found a significant negative correlation between the number of hours spent using electronic devices and the prosocial score (r= -0.128, p=0.011), and most of the included children had scores within the "close to average" category across all scales of mental health status. CONCLUSION: There was a high prevalence of electronic device usage among preschool children, which exceeded the recommended time limit. A significant correlation was observed between electronic device use and mental health scores. Further longitudinal studies are required to understand the nature of this association and its implications for child development.

Screen time, problematic screen use, and eating disorder symptoms among early adolescents: findings from the Adolescent Brain Cognitive Development (ABCD) Study.

PURPOSE: Emerging research evidence suggests positive relationships between higher screen time and eating disorders. However, few studies have examined the prospective associations between screen use and eating disorder symptoms in early adolescents and how problematic screen use may contribute to symptom development. METHODS: We analyzed prospective cohort data from the Adolescent Brain Cognitive Development (ABCD) Study (N = 10,246, 2016-2020, ages 9-14). Logistic regression analyses were used to estimate the longitudinal associations between baseline self-reported screen time and eating disorder symptoms in year two. Logistic regression analyses were also used to estimate cross-sectional associations between problematic screen use in year two (either problematic social media or mobile phone use) and eating disorder symptoms in year two. Eating disorder symptoms based on the Kiddie Schedule for Affective Disorders and Schizophrenia (KSADS-5) included fear of weight gain, self-worth tied to weight, engaging in compensatory behaviors, binge eating, and distress with binge eating. RESULTS: Each additional hour of total screen time and social media use was associated with higher odds of fear of weight gain, self-worth tied to weight, compensatory behaviors to prevent weight gain, binge eating, and distress with binge eating two years later (odds ratio [OR] 1.05-1.55). Both problematic social media and mobile phone use were associated with higher odds of all eating disorder symptoms (OR 1.26-1.82). CONCLUSIONS: Findings suggest greater total screen time, social media use, and problematic screen use are associated with more eating disorder symptoms in early adolescence. Clinicians should consider assessing for problem screen use and, when high, screen for disordered eating. LEVEL OF EVIDENCE: Level III: Evidence obtained from well-designed cohort or case-control analytic studies.

Recent trends and disparities in 24-hour movement behaviors among US youth with mental, behavioral and neurodevelopmental conditions.

BACKGROUND: Meeting 24-h movement behaviors (24-HMB: physical activity [PA], screen time [ST], and sleep [SL]) recommendations may be associated with positive health outcomes among youth with specific mental, behavioral, and neurodevelopmental (MBD) conditions. However, temporal trends and disparities in meeting 24-HMB guidelines in these higher-risk groups have not been investigated, hampering the development of evidence-based clinical and public health interventions. METHODS: Serial, cross-sectional analyses of nationally National Survey of Children's Health (NSCH) data (including U.S. youth aged 6-17 years with MBD conditions) were conducted. The time-trends survey data was conducted between 2016 and 2021. The prevalence of 24-HMB adherence estimates were reported for the overall sample and for various sociodemographic subgroups. The subgroups analyzed included: age group (children[aged 6 to 13 years], adolescents[aged 14 to 17 years]), sex, socioeconomic status, and ethnicity. RESULTS: Data on 52,634 individuals (mean age, 12.0 years [SD,3.5]; 28,829 [58.0 %] boys) were analyzed. From 2016 to 2021 the estimated trend in meeting PA + ST + SL guidelines declined (-0.8 % [95%CI, -1.0 % to -0.5 %], P for trend <0.001), whereas meeting none of 24-HMB guidelines increased (2.2 % [1.8 % to 2.6 %], P for trend <0.001). White participants, children, and boys reported higher estimated prevalence of meeting full integrated (PA + ST + SL) guidelines. DISCUSSION: The temporal trends observed in this study highlight the importance of consistently monitoring movement behavior among MBD youth and identifying variations by sociodemographic groups in meeting 24-HMB guidelines for health promotion within these vulnerable groups.

Fentanyl-positive urine drug screens in the emergency department: Association with intentional opioid misuse and racial disparities.

Background: An increase in opioid-related overdoses, notably from potent synthetic opioids like fentanyl, prompted this consideration of characteristics of emergency department (ED) patients with evidence for illicit fentanyl use or exposure, the correlation with intentional opioid misuse, and subsequent ED management. Methods: A retrospective review was performed of patients presenting to an urban academic medical center ED with evidence for illicit fentanyl use, determined by positive urine drug screens (UDS), from 6/2021 through 11/2021. Participant demographics, comorbidities, ED chief complaint and disposition, and evidence of intentional opioid misuse were considered. Secondary outcomes included provision of buprenorphine/naloxone and/or naloxone kits at discharge, ED recidivism, and six-month mortality. Bivariate comparisons and logistic regression models were performed. Results: Among 409 unique patients, most were white and male with a mean age of 39.4. Approximately half presented with opioid-related complaints. Evidence of intentional opioid misuse was identified in 72.6 % of patients. Black patients had 79 % lower odds of intentional opioid misuse compared to white patients. Regarding ED management, 28.8 % were discharged with buprenorphine/naloxone and 14.0 % with a naloxone kit. Black patients had 63 % lower odds of receiving buprenorphine/naloxone compared to white patients after controlling for covariates. Nearly 6 % of the study population died within six months of the initial ED visit. Conclusion: This fentanyl-focused review describes patient characteristics which largely mirror the epidemiology of the current opioid epidemic; however, despite evidence of objective exposure, it also suggests that Black patients may be less likely to use fentanyl intentionally. It also highlights potential disparities related to ED-based opioid misuse patient management.

New screen-printed electrodes for Raman spectroelectrochemistry. Determination of p-aminosalicylic acid.

BACKGROUND: The availability of new surface enhanced Raman scattering (SERS) substrates is essential to develop quantitative analytical methods. Electrochemistry is an easy, fast and reproducible methodology to prepare SERS substrates on screen-printed electrodes (SPEs). RESULTS: This work proposes new SPEs based on a three-electrode system all made of silver. Using the same ink for the whole electrode system facilitates the fabrication process, reduces production costs, and leads to excellent analytical performance. The results showed that Raman enhancement depends strongly on the type of silver ink. To demonstrate the capabilities of the new electrodes developed, 4-aminosalicylic acid was determined in complex matrices and in the presence of strong interfering compounds such as salicylic acid and acetylsalicylic acid. The proposed analytical method is based on the electrochemical surface oxidation enhanced Raman scattering (EC-SOERS) strategy. AgCl nanocrystals are generated on the working electrode surface, which amplify the Raman signal of 4-aminosalicylic acid. Good figures of merit were obtained both in the absence and in the presence of the interfering compounds, achieving a correct estimation of a 4-aminosalicylic test sample in complex matrices. SIGNIFICANCE: The new SPEs have been demonstrated to be very sensitive and reproducible which, together to the high specificity of the Raman signal, makes this methodology very attractive for chemical analysis.

Immediate and delayed effects of fantastical content on children's executive functions and mental transformation.

Watching fantastical content has been shown to negatively affect young children's executive function (EF) skills. No study has investigated how long these negative effects persist and whether they extend to other cognitive skills. The current experimental study aimed to (1) detect how long fantastical content affects children's EF performance and (2) examine whether watching fantastical content negatively affects children's other (non-EF) cognitive task performance, namely mental transformation. A total of 120 5- and 6-year-old children (M = 66 months, SD = 5.52) were randomly assigned to one of the four following conditions: (a) immediate testing after watching an 8-min non-fantastical cartoon, (b) immediate testing after watching an 8-min fantastical cartoon, (c) 10-min delayed testing after watching a fantastical cartoon, and (d) immediate testing after an 8-min free play (control condition). After exposure to each condition, children were tested on EF and mental transformation measures. Results showed that children watching a fantastical cartoon performed worse on working memory and inhibitory control tasks than children watching a non-fantastical cartoon or playing. However, the 10-min delay between the watching and testing sessions eliminated the negative impact observed on inhibitory control. Groups did not differ on cognitive flexibility and mental transformation. As in previous studies, watching fantastical content negatively affected children's EFs, but this negative impact disappeared in a few minutes and seems unique to EFs. These results suggest that fantastical content may temporarily affect attentional and information processing systems related to EFs.

Children's screen time and psychosocial symptoms at 5 years of age - the role of parental factors.

BACKGROUND AND OBJECTIVES: Electronic media (e-media) has become a universal part of young children's daily lives. Previous studies have found an association between increased screen time and children's psychosocial symptoms. We investigated whether parents' psychological distress and parenting style dimensions explain the association between children's screen time and psychosocial symptoms. Moreover, we investigated whether parents' mental well-being and parenting style dimensions moderate this association. METHODS: We used data from the Finnish CHILD-SLEEP birth cohort study. Parents and the child were assessed when the child was 5 years old (N = 671). The measure of screen time included program viewing from TV and other devices. Child's psychosocial problems and parents' depression, stress and parenting style dimensions were assessed by self-reports. RESULTS: A high level of screen time in children was associated with attention and concentration difficulties, hyperactivity and impulsivity symptoms as well as internalizing and externalizing symptoms among 5-year-olds. For the most part, the associations remained significant despite controlling for parents' mental health, parenting style dimensions and multiple background factors, especially associations relating to attention and concentration difficulties and hyperactivity symptoms were robust. Maternal stress and depression moderated the association between children's screen time and psychosocial symptoms, indicating a more pronounced association among stressed or depressed mothers. CONCLUSION: There is an independent association between children's screen time and psychosocial symptoms which is especially pronounced among those children whose mothers had poorer mental well-being. In clinical practice, the length of screen time should be inquired already at a young age and parents should be offered guidance to reduce the possible ill effects of excessive screen time, as well as help with their own mental health problems.

Corrigendum: Association between meeting 24-h movement guidelines and health in children and adolescents aged 5-17 years: a systematic review and meta-analysis.

[This corrects the article DOI: 10.3389/fpubh.2024.1351972.].

Mapping protein conformational landscapes from crystallographic drug fragment screens.

Proteins are dynamic macromolecules. Knowledge of a protein's thermally accessible conformations is critical to determining important transitions and designing therapeutics. Accessible conformations are highly constrained by a protein's structure such that concerted structural changes due to external perturbations likely track intrinsic conformational transitions. These transitions can be thought of as paths through a conformational landscape. Crystallographic drug fragment screens are high-throughput perturbation experiments, in which thousands of crystals of a drug target are soaked with small-molecule drug precursors (fragments) and examined for fragment binding, mapping potential drug binding sites on the target protein. Here, we describe an open-source Python package, COLAV (COnformational LAndscape Visualization), to infer conformational landscapes from such large-scale crystallographic perturbation studies. We apply COLAV to drug fragment screens of two medically important systems: protein tyrosine phosphatase 1B (PTP-1B), which regulates insulin signaling, and the SARS CoV-2 Main Protease (MPro). With enough fragment-bound structures, we find that such drug screens also enable detailed mapping of proteins' conformational landscapes.

Point-of-care testing device platform for the determination of creatinine on an enzyme@CS/PB/MXene@AuNP-based screen-printed carbon electrode.

Screen-printed carbon electrodes (SPCE) functionalized with MXene-based three-dimensional nanomaterials are reported for rapid determination of creatinine. Ti3C2TX MXene with in situ reduced AuNPs (MXene@AuNP) were used as a coreactant accelerator for efficient immobilization of enzymes. Creatinine could be oxidized by chitosan-embedded creatinine amidohydrolase, creatine amidinohydrolase, or sarcosine oxidase to generate H2O2, which could be electrochemically detected enhanced by Prussian blue (PB). The enzyme@CS/PB/MXene@AuNP/SPCE detected creatinine within the range 0.03-4.0 mM, with a limit of detection of 0.01 mM, with an average recovery of 96.8-103.7%. This indicates that the proposed biosensor is capable of detecting creatinine in a short amount of time (4 min) within a ± 5% percentage error, in contrast with the standard clinical colorimetric method. With this approach, reproducible and stable electrochemical responses could be achieved for determination of creatinine in serum, urine, or saliva. These results demonstrated its potential for deployment in resource-limited settings for early diagnosis and tracking the progression of chronic kidney disease (CKD).