A novel method for gas mixing and distribution in multi-chamber embryo incubators.

BACKGROUND: High-quality control of the gas environment in incubators is crucial for in vitro embryo development, which requires high accuracy, fast recovery, and low gas consumption. OBJECTIVE: In this study, we propose a novel gas mixing and distribution system and method as an alternative solution for multi-chamber embryo incubators. METHODS: The system-based embryo incubator enables a controllable gas circulation process and a quantitative supply of CO2 and N2. To determine the optimal parameters for the mixing time and flow rate of the circulated gases, we conducted contrast experiments on the system-based incubator. To evaluate the performance of the gas system in the incubator, we conducted tests under four different initial conditions, simulating various practical application scenarios. Furthermore, we performed a mouse embryo assay to assess the system's effectiveness. RESULTS: The results show that the system achieved a gas concentration accuracy of ± 0.2% (volume fraction) after stabilization, a minimum recovery time of 5 minutes, an average consumption of 8.9 L/d for N2 and 0.83 L/d for CO2 during routine operation, and a blastocyst rate exceeding 90% observed after 96 hours of culture in the incubator. CONCLUSION: The system and method demonstrate a significant advantage in terms of low gas consumption compared to existing incubators, while still maintaining high accuracy and fast recovery.

[Design of a dynamic measurement system for Bl factor spatial distribution of resonant blood viscoelastic sensor].

Bl factor is a key system parameter of the resonant blood viscoelastic sensor. In this paper, a dynamic measurement system for the spatial distribution of Bl factor based on velocity amplitude and motional impedance was designed. The system extracted the velocity amplitude and motional impedance of the coil under the dynamic condition of driving the sensor to generate simple harmonic oscillations using laser displacement and impedance analysis combined with in-phase/quadrature demodulation algorithm, and controlled the equilibrium position of the coil by adjusting the direct current component of the excitation current to realize the position scanning. In the position interval of [-240, 240] µm, the maximum coefficient of variation of the measurement results was 0.077 3%, and the maximum relative error to the simulation results was 2.937 9%, with a linear fitting correlation coefficient R 2 = 0.996 8. The system can be used to accurately measure the spatial distribution of Bl factor of the resonant blood viscoelastic sensor, which provides a technical support for the verification of the design of the sensor magnetic circuit.

DNA-MnO2 Nanoconjugates Investigation and Application for Electrochemical Polymerase Chain Reaction.

Manganese dioxide (MnO2) nanosheets are emerging for biomedical applications with excellent physical and chemical properties. Adsorption of DNA on MnO2 is important for biosensing, bioimaging, and therapy. Nevertheless, current fundamental understanding about the interaction is preliminary. Herein, UV-vis absorption spectra are applied to systematically explore the biointerfacial interaction between DNA and MnO2 with the factors of salt concentration, pH value, temperature, DNA concentration, and length. The results offer important fundamental insights into the investigation of DNA-MnO2 nanocomposites. Meanwhile, the optimal parameters are applied to construct a screen-printed electrode (SPE) modified with polymerase chain reaction (PCR) primer-decorated MnO2 nanosheets. An electrochemical PCR system is then developed for ultrasensitive detection of circulating tumor DNA (ctDNA). The limit of detection is determined to be 0.1 fM, and high selectivity is demonstrated. Combining the merits of SPE, DNA-MnO2 nanosheets, and an amplified reaction, this developed strategy shows great promise in bioanalysis, clinical disease diagnosis, and biomedicine applications.

[Design and experiment of online monitoring system for long-term culture of embryo].

In the study of embryo development process, the morphological features at different stages are essential to evaluate developmental competence of the embryo, which can be used to optimize and improve the system for in-vitro embryo culture. In this paper, an online monitoring system was designed for long-term culture of embryos, based on a monitoring strategy of low-magnification search and high-magnification observation. Three optical modules of 4× phase contrast, 10× and 20× Hoffman modulation phase contrast were configured in this system to meet the requirements of different fields of view, especially when the size of the embryo increases during the culture. Using an optomechanical system matching design, an error control and alignment test, the resolution of optical imaging was guaranteed, and a relief stereoscopic imaging with high contrast of embryos was obtained. Through low-magnification field of view to identify and locate embryos and high-magnification field of view to capture the details, the system realized online tracking and monitoring of embryos. In addition, we developed and verified an embryo identifying and locating algorithm based on image contour area and definition evaluation. The online monitoring system of in-vitro embryo culture proposed in this paper can track and record the morphological features of embryos without affecting the embryo development, providing a basis for the assessment of embryo development and the optimization of in-vitro culture system.

Peptide cleavage-based electrochemical biosensor coupling graphene oxide and silver nanoparticles.

Herein, a novel electrochemical biosensor for sensitive analysis of prostate specific antigen (PSA) is demonstrated. A specific peptide is employed on the gold electrode as a molecular recognition element for target induced cleavage. In the absence of PSA, graphene oxide (GO) is directly immobilized on the peptide modified electrode, which triggers the aggregation of silver ions and subsequent reduction reaction to form silver nanoparticles (AgNPs). Well defined sharp silver stripping peak can thus be achieved, which stands for a highly characteristic solid-state Ag/AgCl reaction. However, in the presence of PSA, the peptide is specifically recognized and cleaved. The resulted product on the electrode surface cannot aid the immobilization of GO and subsequent formation of AgNPs. Therefore, electrochemical response is decreased remarkably, which can be used to indicate the concentration of PSA. This work demonstrates that the combination of the transduction of peptide cleavage event with GO/AgNPs nanocomposites is a promising attempt for PSA analysis with high sensitivity and selectivity.

Preparation of a Peptide-Modified Electrode for Capture and Voltammetric Determination of Endotoxin.

Endotoxin is the major structural constituent of the outer membrane of Gram-negative bacteria, which is a great threat to human health. Herein, a sensitive electrochemical biosensor for the detection of endotoxin is established by recording the voltammetric responses of the peptide-modified electrode. The utilized peptide has a high affinity for the target endotoxin, which ensures the high selectivity of this method. After the capture of endotoxin on the electrode surface, a negatively charged layer is formed, and the electron-transfer process is significantly hindered because of the increased steric hindrance and the electrostatic repulsion. The declined electrochemical signal could be used to indicate the concentration of endotoxin. This method is simple but effective, which requires limited reagents. Another highlight of this method is its user-friendly operation. Moreover, its applicability in human blood plasma promises its great potential utility in the near future.

An elastography analytical method for the rapid detection of endotoxin.

We present a flexible analytical method for the study of coagulation systems by monitoring elastography (EG). The rapid detection of endotoxin is achieved by the EG analysis of endotoxin-induced limulus amebocyte lysate coagulation. This method is superior to other methods using the same reagents in not only sensitivity but also detecting time.

An aptasensor for detection of potassium ions based on RecJ(f) exonuclease mediated signal amplification.

An electrochemical biosensor for potassium has been developed combining specific potassium-aptamer binding and RecJf exonuclease mediated signal amplification. Generally, the DNA probe with a stem-loop structure containing an anti-K(+) aptamer sequence is designed and modified on a gold electrode. K(+) can specifically bind to the aptamer and a G-quadruplex structure forms, which breaks the original stem-loop structure. The induced single-stranded 5' end can be further digested by RecJf exonuclease, releasing K(+) which can bind to another DNA probe on the electrode. After cycles of RecJf exonuclease cleavage initiated by K(+), the electrochemical signal intensity is significantly decreased, and can be used to determine the concentration of K(+). This aptasensor shows high sensitivity, selectivity as well as excellent stability and accuracy, which provides possibilities for further applications of K(+) assay in clinical diagnosis.

Melamine functionalized silver nanoparticles as the probe for electrochemical sensing of clenbuterol.

Clenbuterol, a member of ß-agonist family, has now been a serious threat to human health due to its illegal usage in the livestock feeding. Herein, we describe the application of melamine functionalized silver nanoparticles (M-AgNPs) as the electrochemical probe for simple, fast, highly sensitive and selective detection of clenbuterol. Generally, AgNPs are prepared and functionalized by melamine. After interacting with melamine modified gold electrode in the presence of clenbuterol, M-AgNPs can be immobilized on the surface of the electrode via the hydrogen-bonding interactions between clenbuterol and melamine. This sandwich structure permits sensitive and selective detection of clenbuterol. Since M-AgNPs can provide a couple of well-defined sharp silver stripping peaks, which stands for a highly characteristic solid-state Ag/AgCl reaction, a rather low detection limit of 10 pM can be achieved. The detection range is from 10 pM to 100 nM, which is quite wide. This developed biosensor can potentially be used for clenbuterol detection in biological fluids in the presence of various interferences.