Glucose Sensor Research Articles

The critical roles of three sugar-related proteins (HXK, SnRK1, TOR) in regulating plant growth and stress responses.

Sugar signaling is one of the most critical regulatory signals in plants, and its metabolic network contains multiple regulatory factors. Sugar signal molecules regulate cellular activities and organism development by combining with other intrinsic regulatory factors and environmental inputs. HXK, SnRK1, and TOR are three fundamental proteins that have a pivotal role in the metabolism of sugars in plants. HXK, being the initial glucose sensor discovered in plants, is renowned for its multifaceted characteristics. Recent investigations have unveiled that HXK additionally assumes a significant role in plant hormonal signaling and abiotic stress. SnRK1 serves as a vital regulator of growth under energy-depleted circumstances, whereas TOR, a large protein, acts as a central integrator of signaling pathways that govern cell metabolism, organ development, and transcriptome reprogramming in response to diverse stimuli. Together, these two proteins work to sense upstream signals and modulate downstream signals to regulate cell growth and proliferation. In recent years, there has been an increasing amount of research on these three proteins, particularly on TOR and SnRK1. Furthermore, studies have found that these three proteins not only regulate sugar signaling but also exhibit certain signal crosstalk in regulating plant growth and development. This review provides a comprehensive overview and summary of the basic functions and regulatory networks of these three proteins. It aims to serve as a reference for further exploration of the interactions between these three proteins and their involvement in co-regulatory networks.

New Class of Optical Blood Glucose Sensors Based on a PMMA Mach–Zehnder Interferometer

New Class of Optical Blood Glucose Sensors Based on a PMMA Mach–Zehnder Interferometer

Flexible Enzyme-Free Gate Engineered Bio-FET Glucose Sensor Based on Nickel-Tungstate Microcrystals

Flexible Enzyme-Free Gate Engineered Bio-FET Glucose Sensor Based on Nickel-Tungstate Microcrystals

Bimetal Thin Film, Semiconductors, and 2D Nanomaterials in SPR Biosensors: An Approach to Enhanced Urine Glucose Sensing.

This work introduces a systematic approach for the development of Kretschmann configuration-based biosensors designed for non-invasive urine glucose detection. The methodology encompasses the utilization of various semiconductors, including Silicon (Si), Germanium (Ge), Gallium Nitride (GaN), Aluminum Nitride (AlN), and Indium Nitride (InN), in combination with a bimetallic layer (comprising Au and Ag films of equal thickness) to enhance the biosensor sensitivity. Additionally, 2D nanomaterials, such as Black Phosphorus and Graphene, are integrated into the semiconductor layers to enhance performance further. These configurations are meticulously optimized through the application of the transfer matrix method (TMM), and the sensing parameters are assessed using the angular modulation method. Among the semiconductors, AlN and GaN exhibit superior results. On these substrates, Graphene and Black phosphorous (BP) layers are applied, resulting in four final structures (thicknesses in nm): BK7/Au(26)/Ag(26)/Si(6)/BP(0.53)/Biosample, BK7/Au(26)/Ag(26)/AlN(14)/BP(0.53)/Biosample, BK7/Au(26)/Ag(26)/GaN(12)/BP(0.53)/Biosample, and BK7/Au(26)/Ag(26)/GaN(12)/Graphene(0.34)/Biosample. These biosensors achieve Sensitivity(° /RIU) and Figure of Merit (FoM) (1/RIU) of 380, 360, 440, 400, and 58.5, 90, 90.65, and 82.4, respectively. Subsequently, these high-performing sensors undergo testing with actual urine glucose samples. Among them, two biosensors, BK7/Au(26)/Ag(26)/AlN(14)/BP (0.53)/Biosample and BK7/Au(26)/Ag(26)/GaN(14)/Graphene(0.34)/Biosample, exhibit outstanding performance, with sensitivities (° /RIU) and FoM (1/RIU) of 394.44 & 294.44, and 112.6 & 92.01 respectively. A comparison is also made with relevant previously published work, revealing improved performance in glucose detection.

Air-Stable Perylene Diimide Trimer Material for N-Type Organic Electrochemical Transistors.

A new method is reported to make air-stable n-type organic mixed ionic-electronic conductor (OMIEC) films for organic electrochemical transistors (OECTs) using a solution-processable small molecule helical perylene diimide trimer, hPDI[3]-C11. Alkyl side chains are attached to the conjugated core for processability and film making, which are then cleaved via thermal annealing. After the sidechains are removed, the hPDI[3] film becomes less hydrophobic, more ordered, and has a deeper lowest unoccupied molecular orbital (LUMO). These features provide improved ionic transport, greater electronic mobility, and increased stability in air and in aqueous solution. Subsequently, hPDI[3]-H is used as the active material in OECTs and a device with a transconductance of 44 mS, volumetric capacitance of ≈250 F cm-3, µC* value of 1 F cm-1 V-1 s-1, and excellent stability (> 5 weeks) is demonstrated. As proof of their practical applications, a hPDI[3]-H-based OECTs as a glucose sensor and electrochemical inverter is utilized. The approach of side chain removal after film formation charts a path to a wide range of molecular semiconductors to be used as stable, mixed ionic-electronic conductors.

Enhancing Glucose Biosensing with Graphene Oxide and Ferrocene-Modified Linear Poly(ethylenimine).

We designed and optimized a glucose biosensor system based on a screen-printed electrode modified with the NAD-GDH enzyme. To enhance the electroactive surface area and improve the electron transfer efficiency, we introduced graphene oxide (GO) and ferrocene-modified linear poly(ethylenimine) (LPEI-Fc) onto the biosensor surface. This strategic modification exploits the electrostatic interaction between graphene oxide, which possesses a negative charge, and LPEI-Fc, which is positively charged. This interaction results in increased catalytic current during glucose oxidation and helps improve the overall glucose detection sensitivity by amperometry. We integrated the developed glucose sensor into a flow injection (FI) system. This integration facilitates a swift and reproducible detection of glucose, and it also mitigates the risk of contamination during the analyses. The incorporation of an FI system improves the efficiency of the biosensor, ensuring precise and reliable results in a short time. The proposed sensor was operated at a constant applied potential of 0.35 V. After optimizing the system, a linear calibration curve was obtained for the concentration range of 1.0-40 mM (R2 = 0.986). The FI system was successfully applied to determine the glucose content of a commercial sports drink.

Single-Component Electroactive Polymer Architectures for Non-Enzymatic Glucose Sensing.

Organic mixed ionic-electronic conductors (OMIECs) have emerged as promising materials for biological sensing, owing to their electrochemical activity, stability in an aqueous environment, and biocompatibility. Yet, OMIEC-based sensors rely predominantly on the use of composite matrices to enable stimuli-responsive functionality, which can exhibit issues with intercomponent interfacing. In this study, an approach is presented for non-enzymatic glucose detection by harnessing a newly synthesized functionalized monomer, EDOT-PBA. This monomer integrates electrically conducting and receptor moieties within a single organic component, obviating the need for complex composite preparation. By engineering the conditions for electrodeposition, two distinct polymer film architectures are developed: pristine PEDOT-PBA and molecularly imprinted PEDOT-PBA. Both architectures demonstrated proficient glucose binding and signal transduction capabilities. Notably, the molecularly imprinted polymer (MIP) architecture demonstrated faster stabilization upon glucose uptake while it also enabled a lower limit of detection, lower standard deviation, and a broader linear range in the sensor output signal compared to its non-imprinted counterpart. This material design not only provides a robust and efficient platform for glucose detection but also offers a blueprint for developing selective sensors for a diverse array of target molecules, by tuning the receptor units correspondingly.

High-performance rGO@CNTs@AgNbS nanocomposite electrode material for hybrid supercapacitor and electrochemical glucose sensor

Due to its outstanding ability to store energy, the hybrid energy storage system known as the supercapattery has attained a lot of attention. These devices give extraordinary power and energy densities than supercapacitors and batteries. In this research, a hydrothermal method is used to synthesize a composite material with equal amounts of both components (a 50/50 weight ratio) of silver niobium sulfide and doped with rGO@CNT. Its potential is evaluated using a variety of electrochemical investigations, including galvanostatic charge–discharge and cyclic voltammetry measurements. The rGO@CNT@AgNbS is considered the most attractive material for electrodes based on the electrochemical analysis results, with a specific capacity of 2750 C/g. Additional investigations, including cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), XRD, SEM, and a 15000-cycle stability test, are carried out to better understand this asymmetric device. The device displayed a significant energy density of 65 Wh kg−1 and a fantastic power density of 2229 W /k g . Besides, the composite devices are used as an electrochemical glucose sensor to detect glucose. The device showed an extraordinary sensitivity (greater than 95%) up to a small level of glucose. This study demonstrates the excellent achievement of composite rGO@CNT@AgNbS electrodes for supercapattery applications, with tremendous power and energy densities.

Artificial intelligence powered glucose monitoring and controlling system: Pumping module.

Diabetes, a globally escalating health concern, necessitates innovative solutions for efficient detection and management. Blood glucose control is an essential aspect of managing diabetes and finding the most effective ways to control it. The latest findings suggest that a basal insulin administration rate and a single, high-concentration injection before a meal may not be sufficient to maintain healthy blood glucose levels. While the basal insulin rate treatment can stabilize blood glucose levels over the long term, it may not be enough to bring the levels below the post-meal limit after 60 min. The short-term impacts of meals can be greatly reduced by high-concentration injections, which can help stabilize blood glucose levels. Unfortunately, they cannot provide long-term stability to satisfy the post-meal or pre-meal restrictions. However, proportional-integral-derivative (PID) control with basal dose maintains the blood glucose levels within the range for a longer period. To develop a closed-loop electronic system to pump required insulin into the patient's body automatically in synchronization with glucose sensor readings. The proposed system integrates a glucose sensor, decision unit, and pumping module to specifically address the pumping of insulin and enhance system effectiveness. Serving as the intelligence hub, the decision unit analyzes data from the glucose sensor to determine the optimal insulin dosage, guided by a pre-existing glucose and insulin level table. The artificial intelligence detection block processes this information, providing decision instructions to the pumping module. Equipped with communication antennas, the glucose sensor and micropump operate in a feedback loop, creating a closed-loop system that eliminates the need for manual intervention. The incorporation of a PID controller to assess and regulate blood glucose and insulin levels in individuals with diabetes introduces a sophisticated and dynamic element to diabetes management. The simulation not only allows visualization of how the body responds to different inputs but also offers a valuable tool for predicting and testing the effects of various interventions over time. The PID controller's role in adjusting insulin dosage based on the discrepancy between desired setpoints and actual measurements showcases a proactive strategy for maintaining blood glucose levels within a healthy range. This dynamic feedback loop not only delays the onset of steady-state conditions but also effectively counteracts post-meal spikes in blood glucose. The WiFi-controlled voltage controller and the PID controller simulation collectively underscore the ongoing efforts to enhance efficiency, safety, and personalized care within the realm of diabetes management. These technological advancements not only contribute to the optimization of insulin delivery systems but also have the potential to reshape our understanding of glucose and insulin dynamics, fostering a new era of precision medicine in the treatment of diabetes.

The Impact of Parental Electronic Health Literacy on Disease Management and Outcomes in Pediatric Type 1 Diabetes Mellitus: Cross-Sectional Clinical Study.

Despite the growing uptake of smart technologies in pediatric type 1 diabetes mellitus (T1DM) care, little is known about caregiving parents' skills to deal with electronic health information sources. We aimed to assess the electronic health literacy of parents caring for children with T1DM and investigate its associations with disease management and children's outcomes. A cross-sectional survey was performed involving 150 parent-child (8-14 years old with T1DM) dyads in a university pediatric diabetology center. Parents' electronic health literacy (eHealth Literacy Scale [eHEALS]), general health literacy (Chew questionnaire and Newest Vital Sign [NVS]), and attitudes toward T1DM care (Parental Self-Efficacy Scale for Diabetes Management [PSESDM] and Hypoglycemia Fear Survey [HFS]) were investigated. Children's treatment, HbA1c level, and quality of life (Pediatric Quality of Life Inventory Diabetes Module [PedsQL Diab] and EQ-5D-Y-3L) were assessed. Multiple linear regression analysis was performed to investigate the determining factors of 6-month average HbA1c. Of the 150 children, 38 (25.3%) used a pen, 55 (36.7%) used a pen plus a sensor, 6 (4.0%) used an insulin pump, and 51 (34.0%) used an insulin pump plus a sensor. Parents' average eHEALS score (mean 31.2, SD 4.9) differed significantly by educational level (P=.04) and the children's treatment (P=.005), being the highest in the pump + sensor subgroup. The eHEALS score showed significant Pearson correlations with the Chew score (r=-0.45; P<.001), NVS score (r=0.25; P=.002), and PSESDM score (r=0.35; P<.001) but not with the children's HbA1c (r=-0.143; P=.08), PedsQL Diab (r=-0.0002; P>.99), and EQ-5D-Y-3L outcomes (r=-0.13; P=.12). Regression analysis revealed significant associations of the child's HbA1c level with sex (β=0.58; P=.008), treatment modality (pen + sensor: β=-0.66; P=.03; pump + sensor: β=-0.93; P=.007), and parents' self-efficacy (PSESDM; β=-0.08; P=.001). Significantly higher parental electronic health literacy was found in T1DM children using a glucose sensor. The electronic health literacy level was associated with parents' diabetes management attitude but not with the child's glycemic control. Studies further investigating the role of parental electronic health literacy in T1DM children managed at different levels of care and the local context are encouraged.

Photoelectrochemical sensor based on Sn3O4/CdS heterojunction for detecting glucose in the body and Cu(Ⅱ) ion

In this work, photoactive composites of Sn3O4/CdS at different ratios were synthesized by a solvothermal method. First, Sn3O4 was synthesized. To further improve its photoelectric performance, Sn3O4/CdS-X(X = n(Sn3O4)/n(CdS)) with different molar ratios were synthesized by solvothermal method. The composition, surface structure, valence state and optical properties of Sn3O4/CdS-X were studied by a series of characterization methods. The test results show that Sn3O4/CdS-X have better photoelectric performance than Sn3O4 and CdS. UV–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) demonstrate Sn3O4/CdS-0.55 exhibits the broadest visible light absorption range (360 ∼ 540 nm) and the strongest ability of photogenerated carrier separation. Based on the above performance advantages, Sn3O4/CdS-0.55 was opted to construct the PEC sensor for glucose and Cu(Ⅱ) ion. The linear range for detecting glucose is 0.5 µM-40 mM, and the LOD is 0.067 µM (S/N = 3). For Cu(Ⅱ) ion, these values are 1–290 µM and 0.066 µM, respectively. Moreover, the sensor shows superior selectivity, stability, and reproducibility, which can be used to detect actual samples.

Facile chemiresistive biosensor functionalized with PANI/GOx and novel green synthesized silver nanoparticles for glucose sensing

This article presents a Glossy Photo-Paper (GPP) based Screen-Printed Chemiresistive Interdigitate Electrode (SPCIDE) for enzymatic glucose sensing. A facile inexpensive screen-printing method was used to print the low sheet resistance Interdigitate Electrodes (IDEs) with graphene as conductive ink on the proposed GPP. The screen-printed IDE was functionalized with Polyaniline (PANI) material by drop-cast technique to create a chemiresistive matrix. Further, for selective sensing of glucose, Glucose Oxidase (GOx) enzymes with Green Synthesized Silver Nanoparticles (GS-AgNPs) were immobilized on the PANI material. The proposed GPP-based SPCIDE sensor was used to detect glucose using amperometric measurements. With a correlation coefficient (R2) of 0.9803 and a lower Limit of Detection (LOD) equal to 198 nM, the proposed SPCIDE glucose sensor displays a linear association between change in current and corresponding glucose concentration in the range of 198 nM to 30 mM. An experimental result shows that the created SPCIDE sensor has a sensitivity of 291.19 µA mM−1 cm−2. The study shows that the proposed method may be used to produce facileGPP-based glucose sensors that are inexpensive, eco-friendly, bio-synthesizable, and biodegradable. This may result in developing a Point-of-Care (PoC) diagnostic kit for glucose testing as needed.

Nanostructured Polyoxometalate-Based Heterogeneous Electrode Materials for Electrochemical Sensing of Glucose.

We exploited a tactic to obtain a low-cost, high-efficiency, pollution-free, and stable nonenzymatic polyoxometalate-based heterogeneous electrode material for electrochemical sensing of glucose. It is first followed by the countercation exchange of K2Na8[Cu4(H2O)2(PW9O34)2] (CuPOM) using cesium chloride to prepare an insoluble CuPOM (Cs-CuPOM), which exhibits a uniform and perfect claviform shape with smooth surface. Further, it was mixed with graphite powder to prepare Cs-CuPOM-modified carbon paste electrode (Cs-CuPOM/CPE) with the Cs-CuPOM content between 15% and 50% in weight. This obtained electrode material Cs-CuPOM shows a better electrochemical sensor activity than Cs-MnPOM, Cs-FePOM, and other reported POM-based electrode materials for glucose oxidation on account of their quicker electron transfer kinetics, which also exhibits conspicuous characteristics with a wide linear range of 5-1500 μM. It also possesses a high sensitivity of 16.3 A M-1 cm-2 and a low limit of detection (LOD) of 0.99 × 10-6 M at the signal-to-noise ratio of 3. The conspicuous sensing feature, low cost, and liable synthetic method can make Cs-CuPOM a promising candidate for the exploitation of a preeminent glucose sensor.

Miniaturized Optical Glucose Sensor Using 1600–1700 nm Near‐Infrared Light

AbstractBlood glucose measurement is crucial for diabetes diagnosis and treatment, but invasive sampling methods have drawbacks. Non‐invasive near‐infrared (NIR) spectroscopy‐based optical glucose sensing has gained attention but faces challenges due to the strong absorbance of NIR light by water and the need for complex equipment. Here, four distinct glucose fingerprints at specific NIR wavelengths: 1605, 1706, 2145, and 2275 nm are identified. Utilizing a surface‐mounted LED with a spectral range of 1600–1700 nm and focusing on the most prominent peaks at 1605 and 1706 nm, a miniaturized and non‐invasive glucose sensor is developed. The device successfully detects in vitro assays of glucose solutions within the physiological range of 50–400 mg dL−1, attaining a limit of detection as low as 10 mg dL−1. The findings demonstrate the feasibility of NIR spectroscopy‐based glucose sensing and its potential applications in non‐invasive point‐of‐care diagnostics, with the potential for extension to other biomarkers in future.

Tailored diffusion limiting membrane for microneedle glucose sensors with wide linear range

Continuous glucose monitoring is very important to daily blood glucose control in diabetic patients, but its accuracy is limited by the narrow linear range of the response of biosensor to the glucose concentration because of the oxygen starvation in tissue and the limited maximum conversion rate of glucose oxidase. In this work, a biocompatible diffusion limiting membrane based on two medical-grade polyurethanes is developed via blending modification to restrict the diffusion flux of glucose to match the oxygen concentration and the maximum conversion rate. The expansiveness of the linear range for the nanomaterials-modified electrode in the glucose biosensor can be achieved through the regulation of two polyurethanes, the solvent, and the thickness of the membrane. In addition, the mass transport of hydrogen peroxide and interfering substances is also limited of the membrane. The in vitro experiments demonstrated that the membrane-modified microneedle biosensor exhibited a rapid response to the concentration variation of glucose, a wide linear range that is sufficient to cover the blood concentration of healthy and diabetic people, the ability to resist the oxygen concentration fluctuation and interfering substances, good reproducibility and long-term stability. The custom wearable electrochemical system, possessing these characteristics, has been proven to accurately monitor the blood concentration in a living rat in real time. This demonstrates a significant potential for application in both daily and clinical blood glucose monitoring.

An intelligent wearable artificial pancreas patch based on a microtube glucose sensor and an ultrasonic insulin pump

In order to improve the living standards of diabetes patients and reduce the negative health effects of this disease, the medical community has been actively searching for more effective treatments. In recent years, an artificial pancreas has emerged as an important approach to managing diabetes. Despite these recent advances, meeting the requirements for miniaturized size, accurate sensing and large-volume pumping capability remains a great challenge. Here, we present a novel miniaturized artificial pancreas based on a long microtube sensor integrated with an ultrasonic pump. Our device meets the requirements of achieving both accurate sensing and high pumping capacity. The artificial pancreas is constructed based on a long microtube that is low cost, painless and simple to operate, where the exterior of the microtube is fabricated as a glucose sensor for detecting diabetes and the interior of the microtube is used as a channel for delivering insulin through an ultrasonic pump. This work successfully achieved closed-loop control of blood glucose and treatment of diabetes in rats. It is expected that this work can open up new methodologies for the development of microsystems, and advance the management approach for diabetes patients.

FeNi Prussian blue analogues on highly graphitized carbon nanosheets as efficient glucose sensors

FeNi Prussian blue analogues on highly graphitized carbon nanosheets as efficient glucose sensors

Amplified frequency-shifted interferometry fiber loop ringdown glucose sensors using side-polished fiber

An amplified frequency-shifted interferometry fiber loop ringdown (FSI-FLRD) sensor is proposed for the concentration measurement of glucose solutions. It detects glucose concentrations by measuring the ringdown distance of the continuous light in the fiber ringdown loop (RDL) instead of the ringdown time of the pulsed light in the loop as in traditional FLRD glucose sensors. A bidirectional erbium-doped fiber amplifier (Bi-EDFA) and a segment of side-polished fiber (SPF) are respectively inserted into the RDL to compensate the loop attenuation and to act as the sensing probe. The proposed optical sensor was tested with glucose solutions in the concentration range from 0 to 14 % at room temperature, which exhibits a linear response with a sensitivity of 0.0013 km−1/% (4.12x10−4 dB/%) for the 0–8 % glucose solutions. Additionally, it also achieved a system stability of 0.75 %, with a measuring resolution of around 2.63 %. The experimental results show the proposed sensor has simple structure, low cost, robust stability and good resolution, and it is a suitable alternative for the detection of glucose concentrations in biological detection, component analysis and on-line quality control in food industry.

Enzyme-chitosan hydrogels for high sensitivity flexible silk-based electrochemical glucose sensor

Developing enzymatic glucose sensors with high stability and excellent sensing performance is beneficial for the diagnosis and real-time monitoring of diabetes. In this study, we developed an enzymatic glucose sensor with the RGO (Reduced Graphene Oxide) /SF (Silk Fibroin) composite membrane as a flexible and conductive substrate, and then PB (Prussian Blue) was deposited on the surface of RGO/SF. To enhance the stability of GOD (Glucose Oxidase) and enzymatic glucose sensor, enzyme-chitosan hydrogel electropolymerized on the PB/RGO/SF electrode surface and at last a Nafion layer was coated on the hydrogel to prevent hydrogel detachment and mitigate the effects of interferent. This developed GOD/PB/RGO/SF sensor exhibits good sensing performance in glucose detection, with a response time of less than 10 s, a sensitivity as high as 230.96 μA mM−1 cm−2 at low concentration, and a linear range of 65.57 μM–10 mM, and it also shows good anti-interference feature and reproducibility, providing the reliable sensing performance for detecting glucose levels in human organisms and drinks. In conclusion, the GOD/PB/RGO/SF flexible sensor developed in this study has good prospects for application in glucose real-time monitoring and flexible sensing device.

Non-enzymatic glucose sensor using mesoporous carbon screen-printed electrodes modified with cobalt phthalocyanine by phase inversion

The development of non-enzymatic glucose electrochemical sensors is still required to be used for the determination of glucose in complex biological media. This study presents a straightforward and remarkably efficient tool for the preparation of highly stable and sensitive glucose electrochemical sensors based on the deposition of cobalt phthalocyanine (CoPc) onto mesoporous carbon screen-printed electrodes (MCs). Results show that the MC electrochemical activation (aMC) followed by phase inversion (PI), which consisted of drop casting of CoPc in dimethylformamide onto a wetting electrolyte leading to the electrode aMC-CoPc/PI, enhanced sensitivity towards glucose determination in complex media. The beneficial need for MC surface activation and PI has been explored by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The aMC-CoPc/PI electrode exhibited the highest electrocatalytic activity of the series (namely, MC-CoPc, MC-CoPc/PI and aMC-CoPc) towards glucose oxidation. By using square wave voltammetry technique, the aMC-CoPc/PI glucose electrochemical sensor demonstrated a sensitivity of 22.3 µA mM−1 and a low detection limit of 27.4 µM (S/N = 3) in a linear dynamic range of 0.1 to 3.5 mM. Additionally, it also displayed high selectivity, robust stability, repeatability and reproducibility toward the quantification of glucose concentration in complex samples such as horse serum, intravenous glucose saline solution and culture medium for sperm cells.