In-situ measurement of urea concentration with an in-fiber SPR-MZI sensor.

A fiber-optic urea sensor based on surface plasmon resonance (SPR) and Mach-Zehnder interference (MZI) combined principle was designed and implemented. By plating gold film on the single-mode-no-core-thin-core-single-mode fiber structure, we successfully excited both SPR and MZI, and constructed two parallel detection channels for simultaneously measurement of urea concentration and temperature. Urease was immobilized on the gold film by metal-organic zeolite skeleton (ZIF-8), which can not only fix a large number of urease to improve measurement sensitivity of urea, but also protect urease activity to ensure the sensor stability. Experimental results indicate that the designed urea sensor with temperature compensation function can detect urea solution with concentration of 1-9 mM, and the sensitivity is 1.4 nm/mM. The proposed measurement method provides a new choice for monitoring urea concentration in the field of medical diagnosis and human health monitoring.

In-situ and label-free measurement of cytochrome C concentration with a Ti2C-MXene sensitized fiber-optic MZI sensor.

BACKGROUND: The concentration of cytochrome C is demonstrated to be an effective indicator of the microbial corrosion strength of metals. Traditional cytochrome C sensor can detect cytochrome C with a low detection limit, but their use is limited by their high cost, cumbersome operation, and susceptibility to malignant environments. In addition, studies on the monitoring of cytochrome C in the field of microbial corrosion has still not been carried out. Therefore, there is a need for a highly sensitive, selective, low-cost, anti-interference, and stable cytochrome C sensor with online monitoring and remote sensing capabilities for in-situ measurement of microbial corrosion strength. RESULTS: This paper proposed a highly sensitive label-free fiber-optic sensor based on Mach-Zehnder interferometer (MZI) for in-situ measurement of the microbial corrosion marker cytochrome C. Two-dimensional Ti2C-MXene material is uniformly immobilized onto the surface of the sensing area to improve the sensitivity, hydrophilicity, and specific surface area of the sensing area, as well as to facilitate the immobilization of specific sensitive materials. The cytochrome C antibody is modified on the surface of Ti2C-MXene to specifically recognize cytochrome C, whose concentration variation can be measured by monitoring the spectral shift of MZI sensor. Results demonstrate a measurement sensitivity of 1.428 nm/µM for cytochrome C concentrations ranging from 0 to 7.04 µM. The detection limit of the sensor is calculated to be 0.392 µM with remarkable performance, including selectivity, stability, and reliability. Besides, the measurement result of the proposed sensor in real microbial corrosive environment is consistent with that of the ideal environment. SIGNIFICANCE AND NOVELTY: This is the first instance of achieving in-situ and label-free measurement of cytochrome C by using a fiber-optic MZI sensor, which undoubtedly provides a feasible solution for the effective monitoring of microbial metal corrosion in the environment.

An in-fiber sensor for simultaneous measurement of cholesterol concentration and temperature based on SPR and MMI.

In this paper, we design an in-fiber two-parameter sensor with multimode fiber (MMF)-Au film coated hollow fiber (HCF)-MMF structure, which can simultaneously excite Surface Plasmon Resonance (SPR) effect and Multimode Interference (MMI) effect. A composite material of Au nanoparticles/ß-cyclodextrin (AuNPs/ß-CD) is deposited on the surface of the Au film coated HCF to realize highly-sensitive measurement of cholesterol concentration. Here, the AuNPs can not only enhance the measurement sensitivity of the SPR sensor, but also increase the numbers of combination sites of ß-CD and cholesterol. Then, to solve the cross-sensitivity problem between temperature and cholesterol, the glycerin is selected as a temperature-sensitive material to fill into the inner channel of the HCF, making the MMI sensor sensitive to temperature, and finally realizing the simultaneous measurement of cholesterol concentration and temperature. The experimental results demonstrate that the wavelength shift of the SPR and the MMI are 12.7 nm and 7.9 nm, respectively, when the cholesterol concentration changes from 0 to 500 nM. The temperature sensitivity of the SPR and the MMI are -0.9 nm/°C and 2.64 nm/°C, respectively, in the temperature range of 30°C-46 °C. In addition, the sensor shows good recognition ability of cholesterol molecules in serum environment, with good stability, selectivity and repeatability, and has broad application prospects in the biomedical field.

Maternal gestational weight gain and adverse pregnancy outcomes in non-diabetic women.

OBJECTIVE: This study investigated the relationship between maternal gestational weight gain (GWG) and the risk of adverse pregnancy outcomes in gestational diabetes mellitus (GDM)-negative pregnant women. METHODS: We did a retrospective cohort study between 1 July 2017, and 1 January 2020, at Women's Hospital, Zhejiang University School of Medicine. Firstly, pregnant women were divided into subgroups according to the entire GWG (inadequate GWG, adequate GWG, and excessive GWG) and GDM status (positive and negative) during pregnancy. Secondly, the whole population of pregnant women with GDM was used as a reference to evaluate the relationship between GWG and adverse pregnancy outcomes in GDM-negative pregnant women. Lastly, subgroup analysis was conducted based on pre-pregnancy body mass index (pp-BMI). RESULTS: A total of 30,910 pregnant women were analysed. Included pregnancy women were divided into three groups based on GWG: 7569 (24.49%) pregnancy women had inadequate GWG, 13088 (42.34%) had adequate GWG, and 10,253 (33.17%) had excessive GWG. In addition to preterm birth and small for gestational age (SGA), the incidence of macrosomia and large for gestational age (LGA) continues to increase from inadequate GWG to excessive GWG groups. Pregnant women without GDM who have excessive GWG are at higher risk of macrosomia and LGA than pregnant women with GDM. Moreover, this risk increased with increasing pp-BMI. Pregnant women without GDM with inadequate GWG were at risk of preterm birth regardless of pp-BMI. Only those with inadequate GWG and pp-BMI < 18.5 kg/m2 had an increased risk of SGA. CONCLUSIONS: In conclusion, inappropriate GWG is strongly associated with adverse pregnancy outcomes, even if they do not have GDM. Therefore, this population should receive attention and management before and during pregnancy.Impact StatementWhat is already known on this subject? Several studies have focused on the GDM population and the risk of adverse pregnancy outcomes, but few have focused on GDM-negative populations. This is because GDM-negative women are perceived to be "safe," leading to less focus on themselves, which can lead to subsequent excessive weight gain during pregnancy. Whether this factor increases the risk of adverse pregnancy outcomes in this population remains unknown.What do the results of this study add? Our study found an inverse relationship between GWG and GDM. Therefore, our study focuses on this group of GDM-negative pregnant women. Their excessive weight gain increases the risk of adverse pregnancy outcomes, even higher than GDM pregnant women.What are the implications of these findings for clinical practice and/or further research? GWG is associated with adverse pregnancy outcomes. Therefore, pregnant women without GDM also need increased attention and management of their weight before and during pregnancy. Prenatal care providers can utilise tools such as diet, exercise counselling, weight tracking, and setting weight gain goals to reduce inappropriate weight gain and mitigate its adverse effects on pregnancy outcomes.

Dual-channel in-fiber SPR sensor for simultaneous and highly sensitive measurement of salinity and temperature.

In this Letter, an in-fiber dual-channel surface plasmon resonance (SPR) sensor is reported that uses polydimethylsiloxane (PDMS)-filled C-type microstructured optical fiber (COF). The COF is made of HF-acid-etched single-sided hole optical fiber (SSHF), and its inner and outer sides are coated with gold film to stimulate SPR. The inner channel is filled with PDMS and acts as the temperature measurement channel, and the outer channel is directly in contact with the salt solution and acts as the salinity measurement channel. Experiments show that the sensor is qualified to detect salinity and temperature simultaneously, and it exhibits a salinity sensitivity of 0.296 nm/‰ in the salinity range of 0-153.32‰ and a high temperature sensitivity of -2.4 nm/°C in the temperature range of 22-44°C. Furthermore, the sensor also enjoys good hysteresis, repeatability, and reversibility in salinity detection. In a word, the high sensitivity, simple preparation, and good integration of the proposed sensor endow it with the potential for deep-sea exploration.

Gestational diabetes mellitus in the COVID-19 pandemic: A retrospective study from Hangzhou, China.

AIMS: Our study aimed to investigate changes in the prevalence of gestational diabetes mellitus (GDM) in the COVID-19 pandemic and postpandemic era and the risk of adverse pregnancy outcomes in pregnant women diagnosed with GDM during the blockade period. METHODS: First, we investigated changes in the prevalence of GDM and the population undergoing oral glucose tolerance tests (OGTT) after the COVID-19 pandemic. We then collected clinical information from pregnant women diagnosed with GDM to explore the risk of adverse pregnancy outcomes in pregnant women with GDM during the COVID-19 pandemic. RESULTS: After the COVID-19 pandemic, the proportion of pregnant women in the total number of outpatient OGTT tests decreased yearly. The ratio was 81.30%, 79.71%, and 75.48% from 2019 to 2021, respectively, with the highest proportion of pregnant women in February 2020 (92.03%). The prevalence of GDM was higher in March 2020 compared to the same period in 2019. However, from 2019 to 2021, the prevalence decreased year by year with 21.46%, 19.81%, and 18.48%, respectively. The risk of adverse pregnancy outcomes for pregnant women diagnosed with GDM during the most severe period of the COVID-19 pandemic did not differ from before the COVID-19 pandemic. CONCLUSIONS: After the COVID-19 pandemic, the prevalence of GDM increased during the most severe period of the epidemic, but the overall prevalence of GDM decreased year by year. In addition, the pandemic did not change the risk of adverse pregnancy outcomes in pregnant women with GDM.

Optical fiber SPR biosensor based on gold nanoparticle amplification for DNA hybridization detection.

An optical fiber SPR biosensor based on multimode fiber (MMF)- hollow core fiber (HCF)-MMF is proposed and experimentally confirmed for in situ DNA hybridization analysis. In order to improve the sensitivity of DNA hybridization detection, a sandwich model based on gold nanoparticles (AuNPs) amplification is proposed. In this model, the probe DNA (pDNA) is first modified on the optical fiber sensing area by covalent bonding, and then the biotinylated target DNA (tDNA) is modified on the AuNPs by the high affinity between biotin and streptavidin. Finally, the tDNA on the surface of the AuNPs specifically hybridizes with the pDNA on the optical fiber to form a sandwich model. The near field coupling enhancement between AuNPs and gold film and the high mass ratio of AuNPs give high sensitivity to DNA hybridization detection. Experimental results show that the sandwich-type fiber SPR sensor has a log-linear response in the DNA concentration range of 1 pM-10 nM, and the sensitivity and detection limit are 4.04 nm/log(µM) and 1pM, respectively. This is 1.44 times more sensitive than that without sandwich assay. In addition, the DNA sensor has good specificity and stability, which foreshadows its great application potential in the fields of disease diagnosis, microbial detection and environmental science.

A plug-and-play optical fiber SPR sensor for simultaneous measurement of glucose and cholesterol concentrations.

A plug-and-play surface plasmon resonance (SPR) dual-parameter optical fiber biosensor is reported, in which Au film was firstly coated on the fiber surface for exciting SPR and the end half of the Au film was modified with Au nanoparticles to generate double SPR resonance valleys. For simultaneous detecting of glucose and cholesterol concentrations, modified P-mercaptophenylboronic acid (PMBA) and ß-cyclodextrin (ß-CD) were subsequently coated on the surface of sensor probe. Due to the cis-diol structure of glucose, it can interact with PMBA, leading to a red shift of one SPR resonant valley, whose maximum wavelength shift is 11.228 nm in the range of 0-1.7 mM glucose concentration. On the same time, the cholesterol molecules can realize the host-guest combination with ß-CD, leading to a red shift of another SPR resonant valley, and the maximum wavelength shift is 18.893 nm in the cholesterol concentration range of 0-300 nM. The detection limits of the sensor to glucose and cholesterol are 0.00078 mM and 0.012 nM, respectively. The enhances the practical value of the dual-parameter sensor. Both theory and experiment results verify the feasibility of the "plug-and-play" sensor to measure the dual biomass of glucose and cholesterol with ultra-low detection limit and good selectivity. The proposed method provides a huge research value for the optical fiber sensor in multi-parameter measurement.