We develop detachable "Cavitas sensors" to apply to the human oral cavity for non-invasive monitoring of saliva glucose. A salivary biosensor incorporating Pt and Ag/AgCl electrodes on a mouthguard support with an enzyme membrane is developed and tested. Electrodes are formed on the polyethylene terephthalate glycol (PETG) surface of the mouthguard. The Pt working electrode is coated with a glucose oxidase (GOD) membrane. The biosensor seamlessly is integrated with a glucose sensor and a wireless measurement system. When investigating in-vitro performance, the biosensor exhibits a robust relationship between output current and glucose concentration. In artificial saliva composed of salts and proteins, the glucose sensor is capable of highly sensitive detection over a range of 5-1000µmol/L of glucose, which encompasses the range of glucose concentrations found in human saliva. We demonstrate the ability of the sensor and wireless communication module to monitor saliva glucose in a phantom jaw imitating the structure of the human oral cavity. Stable and long-term real-time monitoring (exceeding 5h) with the telemetry system is achieved. The mouthguard biosensor will be useful as a novel method for real-time non-invasive saliva glucose monitoring for better management of dental patients.

In this study, a cellulose acetate (CA) membrane is formed as an interference rejection membrane on a glucose sensor to measure glucose in saliva. Glucose in saliva is successfully measured in vivo without any pretreatment of human saliva. A mouthguard (MG) glucose sensor is developed to monitor salivary glucose, which is reported to be correlated with the blood glucose level. Salivary components of ascorbic acid (AA) and uric acid (UA) hinder the accurate measurement of the glucose concentration of human saliva. CA-coated electrodes are prepared to investigate the interference rejection membrane. To measure hydrogen peroxide, which is a reaction product of glucose oxidase, effects of AA and UA are examined. Characteristics of the fabricated biosensor are examined on the basis of artificial saliva. The as-developed MG sensor can quantify the glucose concentration in the range of 1.75–10 000 μmol/L, which includes a salivary sugar concentration of 20–200 μmol/L. For the measurement of saliva samples collected from healthy subjects, the output corresponding to the concentration is confirmed; this suggests the possibility of glucose measurement. This MG glucose sensor can provide a useful method for the unrestricted and noninvasive monitoring of saliva glucose for the management of diabetes patients.

Chiral recognition in host-guest complexations between crown ether hosts (H) and amino acid ester ammonium ion guests (G+) has been evaluated by fast atom bombardment @AB) mass spectrometry (m-nitrobenzyl alcohol matrix). The method uses a 1/1 mixed (for example, GR' and Cis-&+) solution of the guest whose enantiomer is isotopically (deuterium) labeled. Chiral recognition of a given host is simply measured with a given guest from the peak intensity ratio of the two diastereomeric host-guest complex ions as I [(H f GR)+]/I[(H -I-Gs-d,)'] 3 IR/&-d,.Both the degree and the direction of chiral recognition are characterized by the I,&-d, values in the range from 0.5 to 5.4 (IR/&-d3) for the present host-guest combination systems studied. b o n g several synthetic chird crown ethers and related natural host compounds, it has been found that host 5 possesses remarkably large guest dependence upon the chiral recognition properties: (1) toward primary amino acid ester guests 14-21, a high degree of (R)-enantiomer preference (I,& = 3.2-5.4), (2) toward phenylglycine ester guest 22, almost no enantiomer recognition (IR/ZS = l.l), and (3) toward secondary amino acid ester guest 24, a weak (S)-enantiomer preference (IR/ZS = 0.7). It is also shown that the IR/Z~ values measured with the present concentrations are reasonably correlated with the relative thermodynamic stabilities in the corresponding host-guest equilibria in solution (IR/IS I KR/KS) for three typical host-guest combination systems selected (1-22,4-16, and 5-16). Accordingly, the present FABMS/ EL (enantiomer-labeled guest) method can be proposed as a new and practically useful technique for determining chiral recognition properties in the highly structured chiral host-chiral guest complexations.

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