Programmable DNA tweezers-SDA for ultra-sensitive signal amplification fluorescence sensing strategy.

BACKGROUND: DNA tweezers, classified as DNA nanomachines, have gained prominence as multifunctional biosensors due to their advantages, including a straightforward structure, response mechanism, and high programmability. While the DNA tweezers demonstrate simultaneous, rapid, and stable responses to different targets, their detection sensitivity requires enhancement. Some small molecules, such as mycotoxins, often require more sensitive detection due to their extremely high toxicity. Therefore, more effective signal amplification strategies are needed to further enhance the sensitivity of DNA tweezers in biosensing. RESULTS: We designed programmable DNA tweezers that detect small-molecule mycotoxins and miRNAs through simple sequence substitution. While the DNA tweezers demonstrate simultaneous, rapid, and stable responses to different targets, their detection sensitivity requires enhancement. We introduced the Strand Displacement Amplification (SDA) technique to address this limitation, proposing a strategy of novel programmable DNA tweezers-SDA ultrasensitive signal amplification fluorescence sensing. We specifically investigate the effectiveness of this approach concerning signal amplification for two critical mycotoxins: aflatoxin B1 (AFB1) and zearalenone (ZEN). Results indicate that the detection ranges of AFB1 and ZEN via this strategy were 1-10,000 pg mL -1 and 10-100,000 pg mL -1, respectively, with corresponding detection limits of 0.933 pg mL -1 and 1.07 pg mL -1. Compared with the DNA tweezers direct detection method for mycotoxins, the newly constructed programmable DNA tweezers-SDA fluorescence sensing strategy achieved a remarkable 104-fold increase in the detection sensitivity for AFB1 and ZEN. SIGNIFICANCE: The constructed programmable DNA tweezers-SDA ultrasensitive signal-amplified fluorescence sensing strategy exhibits excellent detection performance for mycotoxins. The superb versatility of this strategy allows the developed method to be easily used for detecting other analytes by simply replacing the aptamer and cDNA, which has incredible potential in various fields such as food safety screening, clinical diagnostics, and environmental analysis.

Ultrasound-based scoring system for differential diagnosis of polypoid lesions of the gallbladder.

BACKGROUND AND AIM: Polypoid lesions of the gallbladder may be neoplastic or non-neoplastic. Correct diagnosis would help reduce unnecessary cholecystectomies. This study aimed to determine the predictive value of individual ultrasound characteristics for diagnosis of neoplastic polyps and to build a scoring system based on these characteristics. METHODS: A total of 109 patients with gallbladder polyps ≥ 6 mm underwent conventional ultrasound examination and received finally diagnosis by pathological examination. All images were analyzed to determine characteristics of the lesions. Univariate and multivariate analyses were used to identify the predictors of neoplastic polyps, and a scoring system was built based on multivariate analysis. RESULTS: Maximum diameter, height/width ratio, base width, presence of hyper-echoic spots, and intralesional blood flow were statistically significant (P = 0.011, P = 0.016, P = 0.003, P = 0.031, and P = 0.022, respectively) predictors of neoplastic lesions. The total score = (Maximum diameter, ≥ 13.9 mm = 1, < 13.9 = 0) + (Base width, ≥ 3.5 mm = 1, < 3.4 = 0) + (Height/width ratio, ≤ 1.05 = 1, > 1.05 = 0) + (Hyper-echoic spots, presence = 0, absence = 1) + (Blood flow, presence = 1, absence = 0). Receiver operating characteristic curve showed that the sensitivity, specificity, and accuracy for the risk of neoplastic polyps with scores of 3 or higher were 81.6%, 86.7%, and 84.4%, respectively. CONCLUSION: This ultrasound-based scoring system could be a useful means for differentiating between neoplastic and non-neoplastic gallbladder polyps in the clinic.

Prostate cancer: a comparison of the diagnostic performance of transrectal ultrasound versus contrast enhanced transrectal ultrasound in different clinical characteristics.

To determine whether contrast-enhanced transrectal ultrasound (CE-TRUS) is superior to transrectal ultrasound (TRUS) on diagnosis of prostate cancer, 317 patients were processed TRUS examination with or without SonoVue, then biopsy was performed. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of two techniques were compared in multiple subgroups of PSA level, Digital rectal examination (DRE) and prostate volume on biopsy results. In PSA 4-10 ng/ml and DRE negative groups, CE-TRUS had greater sensitivity and accuracy compared with TRUS by patient (P = .004 and .003; .013 and .005 respectively) and greater sensitivity, accuracy, PPV and NPV by core. When prostate volume was 45-65 ml, CE-TRUS had greater specificity and accuracy by patient and all diagnostic performances were statistically significant by core. CE-TRUS is superior to TRUS on diagnosis of prostate cancer in a designed patient population with lower PSA level, DRE negative findings and modest prostate volume.

Value of contrast-enhanced sonographic micro flow imaging for prostate cancer detection with t-PSA level of 4-10 ng/mL.

OBJECTIVES: To compare the efficiency of contrast-enhanced ultrasonographic micro flow imaging (MFI) with conventional transrectal ultrasound (TRUS) in detecting prostate cancer with serum total prostate-specific antigen (t-PSA) of 4.0-10.0 ng/mL. To evaluate the value of contrast-enhanced ultrasonographic MFI in detecting prostate cancer with t-PSA in diagnostic gray zone. METHODS: 47 patients with t-PSA 4.0-10.0 ng/mL underwent gray scale, power Doppler TRUS and MFI examinations before ultrasound guided biopsies. Biopsies were performed at twelve sites in the base, the mid-gland and the apex of the prostate in each patient, when there was no abnormal ultrasound finding. When an abnormality was present at MFI, the biopsy specimen from the corresponding site was directed toward the abnormal finding. With histological results of prostate biopsy as reference standards, we assessed the cancer detection of these three methods. RESULTS: 564 specimens were collected in this study, in which 101 were prostate cancer confirmed histologically. 152 of 564 specimens were demonstrated abnormal on MFI images, in which 71 were malignant and 81 were benign confirmed histologically. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for MFI in detecting prostate caner were 70.3%, 82.5%, 80.3%, 46.7% and 92.7%, respectively. The sensitivity and NPV for MFI were significantly better than gray scale (38.6%, 86.9%) and power Doppler (32.7%, 86.0%) (P<0.001) TRUS. CONCLUSIONS: Contrast-enhanced ultrasonographic MFI could significantly improve the detection rate of prostate cancer with t-PSA in diagnostic gray zone (4-10 ng/mL) than conventional ultrasound.