In a recent study published in Scientific Reports, researchers developed a sensor for non-invasive glucose determination in body fluids corresponding to saliva.

Study: Monitoring saliva compositions for non-invasive detection of diabetes using a colorimetric-based multiple sensor. Image Credit: goffkein.pro/Shutterstock.com

Background

Diabetes, a metabolic illness, affects people aged 45 and over and is mostly brought on by family history, poor weight loss program, and a high body mass index (BMI).

Diabetes problems corresponding to cardiovascular, renal, and limb amputations may end up from an absence of control. Patients’ glucose levels must be checked several times throughout the day using tests corresponding to fasting blood glucose (FBG), oral glucose tolerance test (OGTT), and glycated hemoglobin (HbA1c).

In regards to the study

In the current study, researchers devised a sensor to discover diabetic individuals based on changes of their salivary metabolites. The sensor’s performance was evaluated qualitatively and quantitatively, specializing in the unique color patterns observed in diabetic patients.

A paper substrate was used to construct a multifunctional sensor to detect and manage diabetes development quickly.

The sensor used porphyrazines, pH-sensitive dyes, and silver nanoparticles (AgNPs) to detect variations in salivary composition between diabetics and non-diabetics. The colorimetric responses from salivary composition evaluation were in comparison with fasting blood glucose (FBG) levels obtained from conventional laboratory tools.

The substrate comprised two layers that were folded over each other. The salivary sample was injected into the primary layer. It penetrated the substrate, reacting with sensor components to bind salivary metabolites with their receptors, causing a color change within the sensor components that was apparent to the naked eye.

The development reduced saliva viscosity interference while shortening the evaluation duration and stopping sensor device elements from moving.

Cobalt, copper, and zinc cores were used with organic dyes [combined with phenylboronic acid (PBA) and tetrabutylammonium hydroxide (TBOH)], and silver nanoparticles [comprising L-arginine, chitosan, and thiomalic acid (TMA) as coating agents] were incorporated as receptors.

The study aimed to supply distinct color patterns for diabetes patients that differed from those of healthy individuals.

Principal component analysis-linear discriminant evaluation (PCA-LDA) was performed to evaluate the sensor’s capability to discriminate between diabetic and non-diabetic individuals based on their salivary metabolic profiles.

For every sample, your entire sensor response was computed, and its association with participants was explored. The repeatability of sensor responses was investigated by making five origami-based sensors. The reactions, expressed as Euclidean norms, were tested for a while to judge the steadiness of the array-based sensor.

Results

Each research group received a singular color map that may be tracked using a scanner. The colorimetric response from salivary composition evaluation correlated with the fasting blood glucose (FBG) value assessed by conventional laboratory tools.

Individuals were categorized as diabetic or non-diabetic, with an accuracy of 89%. The sensor’s performance increased in direct proportion to the dye concentration.

One of the best results were obtained using a molar ratio 4:1 (organic dye: reagent). For data gathering, the sensor response time was 4 minutes. Only two tetrapyrrole macrocycles, Zn-Pa (S2) and Cu-Pa (S3), reacted to saliva chemical substances.

The sensor detected variations in metabolite concentration. The hue of organic dyes mixed with PBA was altered by salivary metabolites amongst individuals with diabetes. Silver nanoparticles produced with chitosan gathered exclusively when diabetic saliva samples were present, and their color modified from yellow to brown.

After introducing thiomalic acid (TMA)-AgNPs to the saliva secretions of people with and without diabetes, this phenomenon was observed. The discoloration of methyl red and TBOH coincided with the blood glucose categories stated.

On account of their distinct properties and sensitivity, sensing receptors based on nanoparticles better-determined blood glucose levels with shorter intervals. The sensor’s response was unaffected by age changes.

Conclusions

Overall, the study findings highlighted the potential of sensors as non-invasive technologies for continuous diabetes monitoring, particularly within the elderly. The sensor’s response was based on color differences within the detecting receptors, facilitating interpretation without operating personnel requirements.

The sensor could detect the chemical content of saliva samples, estimate blood glucose levels, determine mobility, and supply reproducible results.

The sensor’s ease of use, portability, and dependability make it a possible alternative to standard approaches. Nonetheless, on account of the requirement for centrifugation, the sensor’s current use is confined to clinical laboratories.

Future designs might improve the structural characteristics of the salivary sensor through the use of additional layers for pre-treatment and filtering. This might allow for speedier imaging, color evaluation, and final response reporting. Adding receptors that may detect the influence of varied medicines for diabetes therapy is one other objective for future research.

Journal reference:

• Bordbar, M. M., Hosseini, M. S., Sheini, A., Safaei, E., Halabian, R., Daryanavard, S. M., Samadinia, H. and Bagheri, H. (2023) Monitoring saliva compositions for non-invasive detection of diabetes using a colorimetric-based multiple sensor, Nature News. doi: https://doi.org/10.1038/s41598-023-43262-z. https://www.nature.com/articles/s41598-023-43262-z