Dynamic Characterization of Optical Coherence-Based Displacement-Type Weight Sensor.

Dynamic characteristics play a crucial role in evaluating the performance of weight sensors and are essential for achieving fast and accurate weight measurements. This study focuses on a weight sensor based on optical coherence displacement. Using finite element analysis, the sensor was numerically simulated. Frequency domain and time domain dynamic response characteristics were explored through harmonic response analysis and transient dynamic analysis. The superior dynamic performance and reduced conditioning time of the non-contact optical coherence-based displacement weight sensor were confirmed via a negative step response experiment that compared the proposed sensing method to strain sensing. Moreover, dynamic performance metrics for the optical coherence displacement-type weight sensor were determined. Ultimately, the sensor's dynamic performance was enhanced using the pole-zero placement method, decreasing the overshoot to 4.72% and reducing the response time to 0.0132 s. These enhancements broaden the sensor's operational bandwidth and amplify its dynamic response capabilities.

Optical coherence tomography for the early detection of colorectal dysplasia and cancer: validation in a murine model.

BACKGROUND: There is an urgent need to develop a non-invasive imaging technique for detecting colorectal dysplasia and cancer. Technology for early and real-time microscopic assessments to select the most representative biopsy sites would also be of clinical value. In this study, we explored the sensitivity of optical coherence tomography (OCT) in detecting local lesions to demonstrate its potential for the early detection of colorectal dysplasia and cancer. METHODS: An azoxymethane/dextran sodium sulfate mouse model of colorectal carcinogenesis was utilized. Mice were imaged by OCT, and colorectal tissue sections were observed with hematoxylin and eosin staining. The results of the parallel analyses were compared to evaluate the performance of OCT in imaging and early screening of colorectal lesions. RESULTS: Dysplasia and cancer could be distinguished from normal colon tissues based on the OCT images. However, simple morphological changes observed in the OCT images were not sufficient to distinguish different degrees of dysplasia or distinguish dysplasia from cancerous tissues. The Youden index and diagnostic efficiency of OCT for colorectal dysplasia and cancer were 62.50% and 82.14%, respectively, while the sensitivity and specificity were 87.50% and 75.00%, respectively. Further, the positive and negative predictive values were 82.35% and 81.82%, respectively. CONCLUSIONS: Based on our findings, we predict that OCT is a promising non-invasive imaging technique that can offer excellent positive detection rates and diagnostic accuracy for early colorectal dysplasia and cancer. This technique is expected to be valuable in realizing real-time qualitative analysis and guided targeted biopsy.

Optical coherent tomography to evaluate the degree of inflammation in a mouse model of colitis.

BACKGROUND: There is an urgent need to develop a noninvasive imaging technique for the diagnosis of early inflammatory lesions or early and real-time microscopic assessment before selecting the most representative biopsy sites. METHODS: In this study, a dextran sulfate sodium colitis model was developed, and intestinal histological damage scores measured the degree of inflammation in colitis. According to these scores, 6 parameters were designed for hematoxylin and eosin (HE) sections based on morphological changes, and 2 parameters were designed for optical coherence tomography (OCT) images to measure submucosal edema by morphological changes to evaluate inflammation degrees in the colon. Spearman's rank correlation method was used to compare the correlation between the submucosal morphological changes and the different degrees of inflammation. One-way analysis of variance (ANOVA) was used for comparisons among groups, while receiver operating characteristic (ROC) curves of the indicators in HE sections and OCT images were plotted. RESULTS: In HE sections, angle of mucosal folds (r=0.853, P<0.01), length of basilar parts (r=0.915, P<0.01), submucosal area (r=0.819, P<0.01), and height between submucosal and muscular layers (r=0.451, P=0.001) were correlated with the degree of inflammation in colitis. In OCT images, length of basilar parts (r=0.800, P<0.01) and height of submucosa + thickness of muscularis (r=0.648, P=0.001) were correlated with the degree of inflammation and aided the measurement of inflammation in the colon. CONCLUSIONS: Parameters based on morphological changes in OCT images and HE sections were significant indexes for evaluating the degree of inflammation in colitis. OCT images have advantages for future clinical applications in situ, including noninvasiveness and real-time imaging.

High-performance optical coherence velocimeter: theory and applications.

We proposed a high-performance optical coherence velocimeter (OCV) based on broadband optical interference which achieves spatial resolution from interference cancellation or enhancement of different components of the broadband light. There is a challengeable issue for OCV that the interference fringes become blurred when the velocity of detected object is relatively large, hindering the pace of OCV application in high-velocity field. To resolve this, the relationship between blurry coefficient and OCV system parameters (e.g., exposure time, central wavelength, bandwidth of source) was derived. It was found that blurry coefficient changed with oscillatory decay form and reached the minimum at each order blurry velocity. It showed that maximum measurable velocity of OCV systems could reach 10th order blurry velocity. The measurement of vibration of the loudspeaker driven by a function signal generator was employed to experimentally verify the velocity measurement performance of the system. The experiment demonstrated that the developed OCV can provide large velocity measurement ranges from static to 25.2 mm/s with nanometer-level precision and maximum measurable vibration frequency of up to 50 kHz. However, in theory, the theoretical maximum measurable velocity can be up to 1.06 m/s for current OCV configuration. The OCV has high precision, large dynamic range, and high-velocity measurement capability, making it attractive for applications in mechanical structure vibration monitoring and acoustic measurement.

Zein-Paclitaxel Prodrug Nanoparticles for Redox-Triggered Drug Delivery and Enhanced Therapeutic Efficiency.

Prodrug, in which the inactive parent drug with good bioavailability is metabolized into an active drug in the body, is one of the main strategies to target the disease site to improve the drug efficiency and reduce the adverse effects of chemotherapy. Because of the good capability of chemical modification, zein, a plant derived protein, and drugs can be conjugated through environmentally sensitive links to form prodrugs capable of triggered drug release. In this study, a novel prodrug was synthesized using paclitaxel (PTX), zein, and a disulfide linker, and nanoparticles were formed by self-assembly of the prodrug. An effective in vitro triggered release, 80-90% in 5 min, of the prodrug based nanoparticles (zein-S-S-PTX_NP) was successfully approached. The cytotoxicity of zein-S-S-PTX_NP as well as the zein encapsulation of PTX (zein_PTX_NP) and pure PTX on HeLa cells and NIH/3T3 fibroblast cells was tested using MTS assay. It showed that, after the treatment of zein-S-S-PTX_NP at the equivalent PTX concentrations of 0.1, 0.5, 1, and 5 µg/mL, respectively, zein-S-S-PTX_NP had zero damage to normal cells but a similar cytotoxicity to cancer cells as pure PTX. In the animal study, the tumor was 50% of the original size after the treatment of zein-S-S-PTX_NP for 9 days with 3 doses. This study suggested that the novel prodrug based nanoparticle zein-S-S-PTX_NP could be a promising approach in chemotherapy with targeted delivery, improved efficacy, and reduced side effects.

Characterization and reactivity of iron based nanoparticles synthesized by tea extracts under various atmospheres.

Bio-synthesis of Fe NPs in inert (nitrogen N-Fe NPs) and oxygen (O-Fe NPs) atmospheres employing green tea extracts was investigated through SEM, EDS, XPS and FT-IR techniques. The particle sizes of N-Fe NPs and O-Fe NPs were confirmed by SEM showing 84.7 ± 11.5 nm and 117.8 ± 26.2 nm respectively with subsequent evaluation of the percentage composition of Fe and O by EDS. The XPS results showed that the zero-valent iron and iron oxide nanoparticles were found to be dominant synthesized respectively in nitrogen and oxygen atmospheres. The FT-IR spectra further demonstrated that the surface functional groups of Fe NPs were different by varying the synthesis atmosphere. Fe NPs were used to remove methylene blue (MB) to test the reactivity, and the removal efficiency of MB using N-Fe NPs was 98.7%, while that of O-Fe NPs was only 65.3%. Thus it is clearly demonstrated that the synthesis atmosphere has prominent effects on the formation and catalytic properties of Fe NPs.