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Background: Salivary glutathione (GSH), malondialdehyde (MDA), protein, sialic acid (SA) levels, cytological parameters, and tissue factor activities (TFa) were investigated when fresh and after 3, 7, 11, 15, 21, and 30 days (d) of storage at -20 degrees C both in the control and the periodontitis group. Moreover, the control and the periodontits groups were compared and continuity of the significances detected between the two groups were evaluated. Methods: GSH, MDA, SA, protein, and TFa were determined using the methods of Beutler, Yagi, Warren, Lowry, and Quick, respectively. Saliva imprint samples were stained with Giemsa and microscopically examined. Results: When the continuity of the significances of differences between the two groups was investigated, differences continued to be significant for GSH and TFa on days 3, 7, 11, 15, 21, and 30. Cytologically, only the significance detected between leucocyte numbers continued to be significant for 30d. However significance of differences in total protein, MDA, and SA levels on day 0, were interrupted on days 3, 7, and 11, respectively. Conclusion: Saliva samples may be stored for 30d for GSH and TFa analyses in patients with and without periodontitis. However, to compare salivary MDA, SA, and total protein levels in these groups we suggest fresh samples to be studied. (C) 2013 Wiley Periodicals, Inc.

Amaç: Ucuz, kolay ve hızlı üre tayini için immobilize üreaz ve kromojen içeren hidrojel ve kağıt bazlı strip şeklinde üre biyosensörleri geliştirmektir. Gereç ve Yöntem: Üre tayini, pH değişikliklerine duyarlı indikatör içeren sistemdeki üreaz ve üre arasındaki enzimatik reaksiyona dayanmaktadır. Biyosensörlerin oluşturulmasında immobilizasyon materyali olarak filtre kağıdı ve hidrojel kullanıldı. İndikatör olarak ise m-kresol moru ve pH değişimine duyarlılığı yüksek olan boya karışımı kullanıldı. Üre-üreaz reaksiyonu sonucunda, üre konsantrasyonu ve karşılık gelen renk, çıplak gözle semikantitatif olarak ve bir renk analiz cihazı yardımıyla kantitatif olarak değerlendirildi. Ayrıca geliştirilen hidrojel ve kağıt tabanlı üre biyosensörleri çeşitli biyolojik örneklerle test edildi.Bulgular: Reaksiyon ortamının pH'ı üre-üreaz reaksiyonunun sonunda değişti. Buna göre biyosensörün değişen rengi hidrojel tabanlı biyosensör için oda sıcaklığında 15 dakikada ve kağıt tabanlı biyosensör için 1 dakikada çıplak gözle ayırt edildi. Biyosensör üzerinde oluşturulan renkler, diffüz yansıma ultraviyole görünür spektrofotometre ve renk analizörü ile kantitatif olarak doğrulandı. Hidrojel tabanlı biyosensörün lineer aralığı 20-200 mg/dL üre olarak tespit edildi. Kağıt tabanlı biyosensör için lineer aralık ise 10-100 mg/dL üre olarak bulundu. Analizlerin tekrarlanabilirliğinin iyi olduğu gösterildi.Sonuç: Tükürük örneklerinde üre düzeyleri kağıt ve hidrojel tabanlı biyosensörler kullanılarak başarıyla belirlendi. Bu biyosensörlerin yeterli tıbbi donanımı olmayan yerlerde kullanımının uygun olabileceği sonucuna varıldı.Anahtar Sözcükler: Üre, kağıt tabanlı biyosensör, hidrojel tabanlı biyosensör,biyolojik sıvılar, tükürük Aim: It is to develop hydrogel and paper based strip type urea biosensors which contain immobilized urease and chromogen in order to detect urea in a cheap, easy and fast fashion.Materials and Methods: The urea determination was based on enzymatic reaction between urease and urea in the system involving chromogen mix sensitive to pH changes. Filter paper and hydrogel were used as the immobilization material for biosensors. m-Cresol purple dye and a dye mixture which has high sensitivity for pH changes, were used as indicators. As a result of the urea-urease reaction, urea concentration and corresponding color were evaluated semiquantitavely with the naked eye, and quantitatively by using a color analyzer. In addition, the developed hydrogel and paper based urea strip type biosensors were tested with biologic samples.Results: The pH of the reaction medium changed at the end of the urea-urease reaction. The color change on the biosensor was distinguished by naked eyes in 15 minutes for hydrogel based biosensor, 1 minute for paper based biosensor. The colors formed on both biosensors were verified quantitatively by diffuse reflectance ultraviolet-visible spectrophotometer and color analyzer. The linear range was 20-200 mg/dL urea for the hydrogel based biosensor. It was 10-100 mg/dL urea for the paper based biosensor. The assays were shown to have good reproducibility. Conclusion: Urea levels in saliva samples were successfully determined by using hydrogel based and paper based urea biosensors. It was concluded that these biosensors may be suitable for use in places without adequate medical equipment.Key Words: Urea, paper based biosensor, hydrogel-based biosensor, biologicalfluids, saliva 138