Glucose Concentration In Saliva Research Articles

Hollow nanocages heterostructured NiCo-LDH/MWCNTs electrocatalyst for highly sensitive and non-invasive detection of saliva glucose

Monitoring salivary glucose has gained increased attention as a non-invasive approach to prevent and diagnose diabetes. Since the glucose concentration in saliva is lower than that in blood, the development of effective electrocatalysts for highly sensitive glucose detection is thus of great significance. In this study, a hollow nanocage from NiCo-layered double hydroxides (LDH) modified with multi-walled carbon nanotubes (MWCNTs) is designed and further employed as the sensing material to construct a novel non-enzymatic glucose electrochemical sensor with high sensitivity. It is synthesized by utilizing pre-synthesized zeolitic imidazolate framework (ZIF-67)/MWCNTs as a sacrificial template and subsequently conducting a simple solvent-thermal reaction with Ni(NO3)2. Such a hollow nanocage preserves the polyhedral framework structure of the used precursor, where the hollow frame-like structure of NiCo-LDH offers accessible catalytic sites, and MWCNTs provides good conductivity. Their combination brings in a bridging effect between MWCNTs and NiCo-LDH, further leading to a large electrochemical active area and excellent catalytic activity of this hollow nanocage. The constructed sensor exhibits a detection limit as low as 0.03 μM for the glucose detection as well as wide linear ranges of 0.1–3000 μM and 3000–9231.8 μM, corresponding to the sensitivity of 2.55 and 1.15 μA mM−1 cm−2, respectively. Moreover, this sensor enables the tracking of glucose concentration change in salivary before and after food intake. This work offers new highly sensitive sensing materials and potentially valuable approaches for non-invasive glucose detection.

Green synthesized gold nanoparticles and CuO-based nonenzymatic sensor for saliva glucose monitoring.

Glucose, essential for brain and muscle functions, requires careful monitoring in diabetes and other chronic disease management. While blood glucose monitoring provides precise information about these diseases, it remains an invasive method. Saliva glucose monitoring could offer an alternative approach, but the glucose concentration in saliva is very low. In this work, we report a simple, low-cost, highly sensitive nonenzymatic electrochemical glucose sensor. We developed this sensor using green synthesized gold nanoparticles (AuNPs) and wet chemical synthesized copper oxide (CuO) nanoparticles on a screen-printed carbon electrode (Au/CuO/SPCE). The sensor's high sensitivity results from dual amplification strategies using AuNPs and CuO nanomaterials, each demonstrating catalytic activity towards glucose. This shows promising potential for saliva glucose monitoring. The AuNPs were synthesized using an Au precursor and orange peel extract (OPE), yielding stable colloidal AuNPs with a mean diameter of about 37 nm, thus eliminating the need for additional capping agents. Under optimal conditions, amperometric tests revealed that the sensor responded linearly to glucose concentrations ranging from 2 μM to 397 μM with a sensitivity of 236.70 μA mM-1 cm-2. Furthermore, the sensor demonstrated excellent reproducibility, stability and high selectivity for glucose in the presence of different biomolecules. We validated the sensor's efficacy by measuring glucose in human saliva, showing its potential for noninvasive glucose monitoring. This research advances the development of point-of-care devices, positioning the sensor as a promising tool for noninvasive glucose monitoring and improved diabetes management.

Facial preparation of electrochemically stable NiO/ZnO hybrid electrode exhibiting excellent redox activity for enhanced glucose detection

A composite structure of three-dimensional NiO over the ZnO nanorod/Ni foam scaffold was fabricated via hydrothermal synthesis and rare-gas calcination. The strong bonding of NiO with high electron mobility ZnO improved its electrochemical activity and stability. The heterojunction's excellent redox activity attributed to the band-edge potentials of ZnO (CB: −0.72 eV and VB: 2.36 eV) and NiO (CB: −1.136 eV and VB: 2.54 eV). The heterostructure exhibited wide detection range (0.01–5.6 mM), outstanding sensitivity (1382 µA∙mM−1∙cm−2), low detection limit (28 µM), and fast response (4 s) as a glucose-sensing electrode. The built-in electric field at the heterojunction facilitated the charge transfer process from NiO to the electrode, while the large electrochemically active surface area (44.32 cm2) enabled greater availability of active sites, resulting in faster response and higher sensitivity. The heterostructure showed excellent selectivity towards glucose and effectively responded to the glucose concentration in saliva, establishing its suitability for noninvasive glucose monitoring.

Feasibility of using a protein gel for masticatory assessment of older people

Masticatory function plays a crucial role in the breakdown of food for bolus formation and safe swallowing. Chewable silicone gel particles (Optosil) were used for assessing masticatory performance by dentists but such particles were found not suitable for older people due to its hard and dry texture and unfavored flavor. Therefore, with fast growing number of older people who have eating and swallowing difficulties, seeking a suitable model food for masticatory performance assessment becomes an important issue. This study was to develop a glucose-containing model food system for reliable evaluation of the masticatory performance. Three formulas with different amount of gelatin were used to prepare the gels and their textural properties were analyzed. A glucometer was used to measure glucose concentration in saliva. Both young adults (23.5 ± 1.1 years) and older subjects (72.9 ± 5.4 years) were asked to perform mastication tests to verify the reliability of the method. Results showed that the Gel-15% sample gave the best performance and was selected as the test food. Reliability of the current method was proved by the classical standard of Optosil method. Moreover, our findings indicated that masticatory performance was significantly positively correlated with bite force in both young and older adults (young subjects: r = 0.874, p < 0.01; older subjects: r = 0.638, p < 0.01). In conclusions, this study suggested that the newly method could accurately and efficiently measure the masticatory performance of older people.

Enzyme-Free Glucose Monitoring Patch

Monitoring of glucose levels in non-invasive biofluids, such as saliva and sweat, can advance personal health tracking. However, the approach remains challenging due to the low glucose concentration in saliva and sweat, about 100 times lower than in the blood. Commercial glucose sensors rely on glucose oxidase to measure blood glucose levels with enzyme reactions. The enzyme activity varies with pH, oxygen level, and temperature (more than 40ºC). Also, the method often suffers from cross-reactivity with other sugar molecules, such as maltose and xylose [1]. Thus, it is crucial to develop highly sensitive and stable non-enzymatic sensors for detecting glucose in non-invasive biological fluids.In this work, we present an enzyme-free, reagent-free electrochemical glucose monitoring patch based on a glucose imprinted polymer nanocomposite. The nanocomposite comprises redox-active chitosan-ferrocene (Cs-Fc) wrapped multi-walled carbon nanotubes (MWCNTs). The Cs-Fc is a polymer with covalently secured redox-active ferrocene, effectively preventing the out leakage of redox substances [2]. The incorporation of MWCNTs increases the surface area, conductivity, and electron transfer rate. The glucose imprinted layer was grown on the surface of the nanocomposite by electropolymerization of functional monomers o-phenylenediamine (o-PD) and 3-aminophenylboronic acid (APBA) in the presence of glucose templates. The successful removal of template molecules created glucose specific recognition sites in the polymer matrices. The sensor directly detected the presence of glucose upon their binding into these cavities. The electrochemical property of the modified sensor was characterized by cyclic voltammetry (CV) in a potential range of 0-0.5 V at a scan rate of 100 mVs-1 in 1x PBS (pH 7.4) solution. For glucose sensing, the sensor was immersed in a sample solution containing different glucose concentrations for 30 min. We have optimized the composition ratio and assay conditions for sensitive glucose detection. Preliminary results indicated a change in redox peak current of ~2.7 times relative to the control upon adding 1 mM glucose, as shown in Figure 1. The proposed glucose patch is label-free, reagentless, cost-effective, easy fabrication, and expected to be utilized for sensitive and selective glucose detection from sweat.

Clinical effectiveness of implant support for distal extension removable partial dentures: functional evaluation using occlusal force measurement and masticatory efficiency

BackgroundImplant-supported removable partial dentures (ISRPD) are supported at the free-end region with implant retainers. As implant retainers prevent denture settlement and facilitate denture retention, this is intended to improve masticatory performance in comparison with that of conventional removable dentures. In the present study, we evaluated the effect of implant retainers at the free-end region of removable dentures on occlusal force and masticatory efficiency using a pressure-sensitive sheet, and measured glucose concentration in saliva after mastication with gummy candy.MethodsIn the present study, the occlusal force and masticatory efficiency of 13 subjects were measured in the following three conditions: without dentures (Condition 1), wearing dentures but not supported by implants (Condition 2), and wearing dentures supported by implants (ISRPD) (Condition 3). All data were statistically compared.ResultsRegarding the occlusal force, Condition 3 showed significantly higher scores than the other conditions; however, there were no significant differences between Conditions 1 and 2. Regarding the masticatory efficiency, Condition 3 showed significantly higher scores than Condition 2.ConclusionsWith ISRPD, the occlusal force and masticatory efficiency were increased in comparison with those with conventional removable dentures.

Study of Salivary Stress Factor Activity in Patients with Diabetes Mellitus During the Period of Adaptation to Complete Removable Laminar Dentures

Diabetes mellitus is referred to as non-communicable epidemic of the 21st century and the fight against diabetes is one of medical and social challenges. One of its complications is damage to periodontal tissues that is accompanied by tooth loss. Any removable denture is a foreign body being a stress factor for the oral cavity.&#x0D; The objective of the research was to study dynamic changes in the activity of stress factor indicators, namely salivary cortisol, glucose and alpha-amylase levels in diabetic patients after prosthodontic treatment with complete removable laminar dentures.&#x0D; Materials and Methods. For this study, patients at the age of 45 to 74 years were divided into two groups: Group I included 52 edentulous patients with type 2 diabetes mellitus who were treated with acrylic resin complete removable laminar dentures; Group II comprised 52 edentulous patients without endocrine pathology who were treated with acrylic resin complete removable laminar dentures as well. Saliva served as the study material. The enzyme-linked immunosorbent assay was used to determine salivary cortisol levels. Glucose concentration in saliva was determined by a unified enzymatic method. Alpha-amylase activity was determined by the enzymatic colorimetric method.&#x0D; Results. According to the research results, before prosthodontic treatment, salivary cortisol levels of patients with diabetes mellitus were 2.4 times higher as compared to patients without somatic pathology. In phase I of adaptation to complete removable laminar dentures, in patients with diabetes mellitus, salivary cortisol concentration increased drastically by 1.4 times as compared to the indicator before prosthodontic treatment (5.61±0.83 ng/ml vs. 4.02±0.65 ng/ml, p&lt;0.01), while in the group of patients without endocrine pathology, cortisol levels increased by 1.2 times; salivary glucose level of patients with diabetes mellitus increased by 1.3 times, while in patients without endocrine pathology, it increased by 1.1 times; in patients of Group I, salivary alpha-amylase levels increased by 1.2 times, while in patients of Group II, salivary alpha-amylase concentration increased by 1.05 times.&#x0D; Conclusions. In patients with diabetes mellitus, changes in saliva composition indicate a significant reduction in the adaptation mechanisms, that complicates and significantly prolongs the period of adaptation to complete removable laminar dentures.

Glucose effect on Candida albicans biofilm during tissue invasion

ObjectiveTo evaluate, in vitro, the effect of two glucose concentrations (0.1 mM and 1.0 mM, simulating glucose concentration in saliva of healthy and diabetic individuals) on Candida albicans biofilm grown on epithelial monolayer. Material and MethodsC. albicans was inoculated on epithelial monolayers supplemented with 0.1 mM, 1.0 mM or no glucose. Control groups without C. albicans were also evaluated. Tissue response was assessed through the production of Interleukin-1α, Interleukin-8, Interleukin-6, Interleukin-10 and tumor necrosis factor-α. The complex of monolayer and biofilms were evaluated by quantitative reverse transcription polymerase chain reaction for expression of E-cadherin (CDH1), Caspase-3 (CASP3), β-defensin-1 (DEFB-1) and β-defensin-3 (DEFB-3). The biofilm architecture was visualized by confocal laser scanning microscopy. ResultsThe production of Interleukin-1α and Interleukin-8 were increased in the presence of C. albicans (p < 0.05). Glucose did not interfere in the release of any cytokine evaluated. C. albicans downregulated transcripts for CDH1 (p < 0.05). Glucose did not induce a significant change in CDH1, CASP3, DEFB-1 and DEFB-3 messenger RNA expression. The biofilms were more structured in the presence of glucose, but no difference in the diffusion of hyphae through the epithelial cells were observed. ConclusionsThe data suggest that glucose concentration does not affect the behavior of C. albicans during tissue invasion and other mechanisms must be related to the greater susceptibility of diabetic individuals to candidiasis.

Polyethyleneimine-Stabilized Platinum Nanoparticles as Peroxidase Mimic for Colorimetric Detection of Glucose.

Colorimetric detection of glucose using enzyme-mimic nanoparticles (NPs) has been drawing great attention. However, many NPs lack good stability in solution, which results in reduced color change of substrates in colorimetric detection. Liner soluble macromolecules with high cationic density may be suitable candidates for the stabilization of NPs. Herein, we prepared polyethyleneimine-stabilized platinum NPs (Ptn-PEI NPs) for colorimetric detection of glucose. The platinum NPs (Pt NPs) used in this system had small size (from 3.21 to 3.70 nm) and narrow size distribution. Pt50-PEI NPs had high stability within one week with a hydrodynamic size of ∼25 nm and slightly positive zeta potential. Pt50-PEI NPs-catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, generating blue oxidized TMB (oxTMB), which indicated the peroxidase-like property of Pt50-PEI NPs. The optimal condition for this reaction was pH = 4.0 at 30 °C. More importantly, Pt50-PEI NPs were successfully used to detect glucose concentration by a colorimetric method with high selectivity. The established method had a linear concentration range from 10 to 5000 μM with a detection limit of 4.2 μM. For example, the concentration of glucose in saliva was tested to be 0.15 mM using our method. The high stability of Pt50-PEI NPs enhanced the high accessibility of the active center of Pt NPs for substrates and consequent excellent catalytic property. This established method has great potential to be used in various applications for glucose detection in the future.

Simple Glucose Measurement System Based on Uncladded Fiber Bragg Grating Etched with Nitric Acid

The demand for a non-invasive, fast, and accurate glucose detection for diabetic patients is increasing nowadays. It is predicted that diabetic patient will increase from 415 million people at 2018 to 640 million people at 2050. Glucose is also present in saliva, therefore glucose concentration measurement in saliva can be an alternative way during diabetics monitoring. In this study, we measure 0-60% glucose concentration through optical systems. The optical system consists of an erbium-doped fibber laser, uncladded fiber bragg gratings that have been etched with nitric acid (HNO3), and optical spectrum analyser (OSA). The measured parameter is a Bragg wavelength shift due to changes in glucose solution concentration. The results show that the wavelength shifts to lower value (blue shift) as the glucose concentration increases. The sensitivity obtained from this measurement system is 1.2 pm/% in glucose solution. This result is a preliminary study to detect glucose concentration in saliva based on Fibber Bragg Grating which has advantages for diabetic patients such as simple setup, non-invasive, fast, and low cost.

Salivary diagnostics on paper microfluidic devices and their use as wearable sensors for glucose monitoring.

Microfluidic paper-based devices (μPADs) and wearable devices have been highly studied to be used as diagnostic tools due to their advantages such as simplicity and ability to provide instrument-free fast results. Diseases such as periodontitis and diabetes mellitus can potentially be detected through these devices by the detection of important biomarkers. This study describes the development of μPADs through craft cutter printing for glucose and nitrite salivary diagnostics. In addition, the use of μPADs integrated into a mouthguard as a wearable sensor for glucose monitoring is also presented. μPADs were designed to contain two detection zones for glucose and nitrite assays and a sampling zone interconnected by microfluidic channels. Initially, the analytical performance of the proposed μPADs was investigated and it provided linear behavior (r2 ≥ 0.994) in the concentration ranges between 0 to 2.0mmolL-1 and 0 to 400μmolL-1 for glucose and nitrite, respectively. Under the optimized conditions, the limits of detection achieved for glucose and nitrite were 27μmolL-1 and 7μmolL-1, respectively. Human saliva samples were collected from healthy individuals and patients previously diagnosed with periodontitis or diabetes and then analyzed on the proposed μPADs. The results found using μPADs revealed higher glucose concentration values in saliva collected from patients diagnosed with diabetes mellitus and greater nitrite concentrations in saliva collected from patients diagnosed with periodontitis, as expected. The results obtained on μPADs did not differ statistically from those measured by spectrophotometry. With the aim of developing paper-based wearable sensors, μPADs were integrated, for the first time, into a silicone mouthguard using a 3D-printed holder. The proof of concept was successfully demonstrated through the monitoring of the glucose concentration in saliva after the ingestion of chocolate. According to the results reported herein, paper-based microfluidic devices offer great potential for salivary diagnostics, making their integration into a silicone mouthguard possible, generating simple, low-cost, instrument-free, and powerful wearable sensors.

Sensitive electrochemical nonenzymatic glucose sensing based on anodized CuO nanowires on three-dimensional porous copper foam.

In this work, we proposed to utilize three-dimensional porous copper foam (CF) as conductive substrate and precursor of in-situ growth CuO nanowires (NWs) for fabricating electrochemical nonenzymatic glucose sensors. The CF supplied high surface area due to its unique three-dimensional porous foam structure, and thus resulted in high sensitivity for glucose detection. The CuO NWs/CF based nonenzymatic sensors presented reliable selectivity, good repeatability, reproducibility, and stability. In addition, the CuO NWs/CF based nonenzymatic sensors have been employed for practical applications, and the glucose concentration in human serum was measured to be 4.96 ± 0.06 mM, agreed well with the value measured from the commercial available glucose sensor in hospital, and the glucose concentration in saliva was also estimated to be 0.91 ± 0.04 mM, which indicated that the CuO NWs/CF owned the possibility for noninvasive glucose detection. The rational design of CuO NWs/CF provided an efficient strategy for fabricating of electrochemical nonenzymatic biosensors.

Oral Sugar Clearance in Individuals with Oral Motor Dysfunctions

Feeding problems due to impaired oral motor functions resulting in prolonged meals are common among persons with brain damage. The aim of the present investigation was to study the oral sugar clearance in 16 individuals with oral motor dysfunction (OMD) and 16 individuals with normal oral functions (control group). Repeated saliva samples were collected on filter paper discs at two locations before and during 30 min after intake of a glucose tablet. The individuals with OMD had significantly higher initial glucose concentrations in saliva and longer glucose elimination time compared to the control group. For some of the subjects with OMD, sugar clearance was extremely slow. The sugar clearance time was positively related to the severity of drooling problems, but not to the degree of dysphagia. The results from this study indicate that individuals with OMD have an increased risk of dental caries.

Caries and saliva in 12–18‐year‐old diabetics and controls

Eighty-five 12-18-yr-old adolescents suffering from insulin-dependent diabetes mellitus (IDDM) and their healthy age- and sex-matched controls were investigated with respect to dental caries, salivary flow rate, pH and buffering capacity of saliva, counts for lactobacilli and mutans streptococci, and salivary glucose content. The diabetics had their disease well controlled according to the HbA1 levels. The results showed no statistically significant difference between diabetics and controls in DMF and DMFS indexes and the number of initial caries lesions. Mean number of initial caries lesions was 3.2 in diabetics, 2.3 in controls. Mean stimulated salivary flow rate was 1.2 ml/min in the patients, 1.4 ml/min in the controls. The pH and buffering capacity values were 7.3 and 4.8 in the patients, 7.4 and 5.1 in the controls, respectively. High counts of mutans streptococci (> 10(6) CFU/ml) and lactobacilli (> 10(5) CFU/ml) were observed more often, but not significantly so, among the patients than in the controls. The mean concentration of glucose in saliva was 10.3 micrograms/ml in the patients, 9.7 1 microgram/ml in the controls. Thus, if the patients' IDDM is well controlled, their salivary and caries data does not differ from that of healthy controls.

Mutans streptococci and lactobacilli in saliva from children with insulin-dependent diabetes mellitus.

The quantitative distribution of mutans streptococci and lactobacilli in saliva of insulin-dependent diabetic children was compared with a group of healthy children and related to the metabolic control of the disease. The study group, consisting of 94 boys and girls (age 4-19) with type 1 diabetes was matched by sex and age with a non-diabetic control group. Stimulated whole saliva was collected and flow rate, buffer capacity and the levels of mutans streptococci and lactobacilli were analysed in all children. In the diabetic group, total salivary proteins and glucose content of saliva were determined. Data on caries experience were recorded from the dental cards of all children. There were no difference in the distribution or number of mutans streptococci between the groups, but significantly (p less than 0.05) lower levels of lactobacilli were found among the diabetic children. The number of lactobacilli was positively correlated (p less than 0.05) to glucose concentration in saliva. There was no difference in the prevalence of caries between the groups. The present findings suggest that the dietary treatment of young insulin dependent diabetics gives rise to a reduced number of lactobacilli in saliva but does not affect the mutans streptococci.

Secretion of glucose in human parotid saliva after carbohydrate intake.

The aims of the present investigation were, first, to follow the secretion of free glucose in parotid saliva in various subjects after a single oral intake of different carbohydrates, and second, to compare the salivary glucose concentration with the concentration in blood. Twenty healthy subjects, three women and 17 men, 20-35 yr of age, participated. They were asked not to eat or drink anything from 10 p.m. the night before the examination. 75 g of carbohydrate (glucose, fructose, or sucrose) dissolved in 300 ml water was ingested the next morning at 8 a.m. One experimental series with glucose was performed in triplicate in 10 of the subjects. Approximately 1.5 ml of citric acid-stimulated parotid saliva was collected before (0 min) and 15, 30, 45, 60, and 120 min after the intake. Salivary concentration of glucose was analyzed enzymatically. Most of the 0-min samples showed a variation in glucose concentration from 5 to 25 mumol/l. After the glucose, fructose, and sucrose intakes, the salivary glucose level increased about 2-4 times, especially in the 30-min samples. A large inter- as well as intra-individual variation was found both in the 0-min samples and in the samples collected after the different intakes. The correlation between the glucose concentration in saliva and blood was higher after than before the carbohydrate intakes.

Oral glucose clearance in subjects with high or low salivary levels of Streptococcus mutans and lactobacilli.

The ability to eliminate sugar from the oral cavity was studied in subjects with high or low numbers of salivary Streptococcus mutans and lactobacilli. The glucose concentration in saliva was determined after consumption of biscuits using the Gloxtest, and the logarithms of the glucose values were plotted against time. The sugar clearance time was measured where the slope of the plot intersected with a glucose level of 1 mg/ml. Subjects with a high level of S. mutans had a significantly longer clearance time than subjects with a low level. More salivary lactobacilli were found in a subject group with a long sugar clearance time than in a group with a fast clearance rate.

Saliva and breast milk composition during the menstrual cycle of women.

Two acute changes in breast milk composition occur during the ovulatory menstrual cycle of women. To determine whether these changes were peculiar to the mammary gland, the composition of unstimulated whole saliva was followed during the menstrual cycle of women. This investigation showed acute, 3-9-fold increases in the concentration of glucose in saliva during the ovulatory menstrual cycle of lactating women. These changes were synchronous with changes in the concentrations of Na and K in breast milk. In contrast to salivary glucose, milk glucose decreased at these times. Milk glucose values were 1.3-fold lower on these days than on the days preceding and following the decrease. Similar acute increases were observed in salivary glucose of non-lactating women. The total duration of the changes in milk and saliva composition was 12-32 h. No cyclic changes in the concentration of glucose were observed in the saliva from women taking oral contraceptives. Since two different epithelial glands are affected simultaneously during the menstrual cycle, it is likely that a hormonal mechanism is involved. Moreover, since the acute increases in salivary glucose also occurred in non-lactating women, we suggest that the factors causing the changes in milk composition are not just a consequence of lactation and are probably closely associated with the hormones controlling the menstrual cycle in all women.

Secretion of glucose-C 14 by dog parotid gland

Following the administration of glucose-C 14 to the dog, the unaltered radioactive glucose molecule can be identified in the parotid saliva by means of chromatography. The concentration of glucose in saliva is low, averaging but 3–4 per cent of the plasma concentration. The amount of radioactivity in the parotid saliva increases as the rate of salivary flow increases. Stop-flow studies indicate that the primary site for transport of glucose from plasma to saliva is in the intralobular ducts. The results of this technique, in combination with other data, strongly suggest that glucose enters the saliva by a passive process.