Detection of Periodontal Disease Marker with Geometrical Transformation of Ag Nanoplates.

Alkaline phosphatase (ALP) and interleukin-1beta (IL-1ß) are crucial salivary biomarkers for the diagnosis of periodontal disease that harms the periodontal tissue along with tooth loss. However, there has been no way of sensitive and portable detection of both biomarkers in saliva with multivariate signal readout. In this work, we design the multicolorimetric ALP and IL-1ß sensing platform based on geometrical transformation of silver nanoplate transducer. By utilizing enzymatic activity of ALP that dephosphorylates p-aminophenol phosphate (p-APP) to p-aminophenol (p-AP), localized surface plasmon resonance properties of silver nanoplate vary with ALP and show a distinct color change from blue to yellow based on a controlled seed transformation from triangular to hexagonal, rounded pentagonal, and spherical shape. The multicolor sensor shows an ALP detection range of 0-25 U/L with a limit of detection (LOD) of 0.0011 U/L, which is the lowest range of LOD demonstrated to date for state-of-the-art ALP sensor. Furthermore, we integrate the sensor with the conventional ELISA to detect IL-1ß for multicolor signaling and it exhibits a linear detection range of 0-250 pg/mL and an LOD of 0.066 pg/mL, which is 2 orders of magnitude lower than the monochromic conventional ELISA (LOD of 3.8 pg/mL). The ALP multicolor sensor shows high selectivity with a recovery of 100.9% in real human saliva proving its reliability and suitability for the readily accessible periodontal diagnosis with multivariate signal readout.

Solid-state colorimetric polydiacetylene liposome biosensor sensitized by gold nanoparticles.

Polydiacetylene (PDA), a conjugated polymer, has attracted attention for realization of a label-free real-time colorimetric biosensor because it exhibits large and rapid colorimetric responses upon the binding of biomolecules. This is due to the conformational distortion of its conjugated backbone. However, solid-state PDA biosensors for point-of-care diagnosis remain unexplored. We describe a highly sensitive solid-state biosensor based on PDA liposomes. We employed gold nanoparticles (AuNPs) on PDA liposomes as the molecular-binding-signal sensitizer, which provides additional conformational distortion in the backbone structure of PDA by exerting steric repulsion to the attached biomolecules. To prove the concept, AuNPs and a thrombin-binding-aptamer were individually functionalized on PDA liposomes, which were attached to a substrate for the detection of thrombin. We found that the sensitivity was enhanced 2.5 times in the presence of AuNPs compared with the case without AuNPs. Because the steric repulsion of the AuNPs is target-independent, we believe that our solid-state biosensor provides a path toward advanced solid-state biosensors.

Multicolor diagnosis of salivary alkaline phosphatase triggered by silver-coated gold nanobipyramids.

Alkaline phosphatase (ALP) is one of the most versatile biomarkers for early detection of several diseases, such as oral carcinomas and periodontitis; therefore, great efforts have been dedicated for developing an ALP biosensor. Multicolor detection of ALP in saliva is ideal for a point-of-care diagnosis; however, this approach is very challenging since spectral responses over wavelengths of several tens of nanometers have thus far remained difficult to achieve. In this work, a colorimetric biosensor for ALP assay has been developed based on ALP affinity to dephosphorylate glucose phosphate into glucose, which has the affinity to deposit Ag nanoshells onto Au nanobipyramids with a multicolor response. This approach provides a blue shift of localized surface plasmon resonance (LSPR) as large as 190 nm corresponding to distinctive color changes, from yellowish brown to red based on the thickness of the formed Ag shell around the Au nanobipyramids. The change in the LSPR has been conducted for highly sensitive quantitative bioassay of ALP with a detectable multicolor change with linear dynamic range of 0.1-20 U/L and low limit of detection (LOD) of 0.085 U/L. Furthermore, the developed multicolor ALP biosensor exhibits high selectivity with high recovery of 98.6% demonstrating  its reliability and suitability for a point-of-care diagnosis.

Recent Advances in Aptamer Sensors.

Recently, aptamers have attracted attention in the biosensing field as signal recognition elements because of their high binding affinity toward specific targets such as proteins, cells, small molecules, and even metal ions, antibodies for which are difficult to obtain. Aptamers are single oligonucleotides generated by in vitro selection mechanisms via the systematic evolution of ligand exponential enrichment (SELEX) process. In addition to their high binding affinity, aptamers can be easily functionalized and engineered, providing several signaling modes such as colorimetric, fluorometric, and electrochemical, in what are known as aptasensors. In this review, recent advances in aptasensors as powerful biosensor probes that could be used in different fields, including environmental monitoring, clinical diagnosis, and drug monitoring, are described. Advances in aptamer-based colorimetric, fluorometric, and electrochemical aptasensing with their advantages and disadvantages are summarized and critically discussed. Additionally, future prospects are pointed out to facilitate the development of aptasensor technology for different targets.

Correction to "Dual-Surfactant-Capped Ag Nanoparticles as a Highly Selective and Sensitive Colorimetric Sensor for Citrate Detection".

[This corrects the article DOI: 10.1021/acsomega.9b04199.].

Correction: Prevalence, Predictors, and Characteristics of Waterpipe Smoking Among Jazan University Students in Saudi Arabia: A Cross-Sectional Study.

[This corrects the article DOI: 10.5334/aogh.2912.].

A skin-interfaced microfluidic platform supports dynamic sweat biochemical analysis during human exercise.

Blood lactate concentration is an established circulating biomarker for measuring muscle acidity and can be evaluated for monitoring endurance, training routines, or athletic performance. Sweat is an alternative biofluid that may serve similar purposes and offers the advantage of noninvasive collection and continuous monitoring. The relationship between blood lactate and dynamic sweat biochemistry for wearable engineering applications in physiological fitness remains poorly defined. Here, we developed a microfluidic wearable band with an integrated colorimetric timer and biochemical assays that temporally captures sweat and measures pH and lactate concentration. A colorimetric silver nanoplasmonic assay was used to measure the concentration of lactate, and dye-conjugated SiO2 nanoparticle-agarose composite materials supported dynamic pH analysis. We evaluated these sweat biomarkers in relation to blood lactate in human participant studies during cycling exercise of varying intensity. Iontophoresis-generated sweat pH from regions of actively working muscles decreased with increasing heart rate during exercise and was negatively correlated with blood lactate concentration. In contrast, sweat pH from nonworking muscles did not correlate with blood lactate concentration. Changes in sweat pH and blood lactate were observed in participants who did not regularly exercise but not in individuals who regularly exercised, suggesting a relationship to physical fitness and supporting further development for noninvasive, biochemical fitness evaluations.

Footcare knowledge and practice among diabetic patients attending primary health care centers in Jazan region, Saudi Arabia.

Background: Diabetic foot is one of the significant complications of diabetes mellitus, associated with a high risk of morbidity and mortality. Patients' knowledge of, and willingness to practice, good footcare are essential and may decrease these risks. This study was conducted to assess adult diabetic patients' knowledge of footcare and willingness to put their knowledge into practice. Method: A cross-sectional observational study was conducted on adult diabetic patients in the central area of the Jazan Region using patients' responses to a questionnaire. Descriptive statistics were calculated for study variables, and the Pearson chi-squared test was used to compare categorical data. Results: A total of 410 diabetic patients were included in this study. The mean age of the participants was 56.7 years. The mean duration of their diabetes mellitus (DM) to date was 9.2 years, and 63% had complications of diabetes. For the questionnaire, 56% of the patients gave incorrect responses to the knowledge of the footcare section and 81% to the willingness to practice footcare section. Highly educated patients have better knowledge and practice of diabetic footcare than those who are less educated (77% vs. 23%, p < 0.05), (37% vs. 20%, p < 0.05), respectively. A statistically significant difference exists between patients with good and poor knowledge scores. Conclusion: This study demonstrates that the knowledge and practice of footcare among DM patients are poor. Therefore, appropriate patient information programs are needed to increase patients' understanding of their illness and how to manage it.

A colorimetric alkaline phosphatase biosensor based on p-aminophenol-mediated growth of silver nanoparticles.

Alkaline phosphatase (ALP) is an enzyme that catalyzes the dephosphorylation of proteins, nucleic acids, and biomolecules. It is a potential biomarker for diverse diseases such as breast cancer, osteopenia, and hepatobiliary. Herein, we developed a colorimetric sensor for the ALP assay based on its enzymatic activity to dephosphorylate the p-aminophenol phosphate (pAPP) into pAP. In a solution containing silver nanoparticles (AgNPs) and Ag+ ions prepared using a low concentration of NaBH4, pAP mediates the growth of AgNPs by reducing the concentration of Ag+ ions to enhance the intensity of localized surface plasmon resonance as the pAPP cannot induce a reduction of the remaining Ag+ due to the masking of the hydroxyl with phosphate. The quantitative assay of the ALP was demonstrated via the colorimetric detection of the pAP-mediated growth of AgNPs in the presence of an ALP. The highly sensitive enzymatic growth of AgNPs provided a wider dynamic linear range of 0.5-225 U/L with a lower limit of detection of 0.24 U/L than that previously reported. The use of pAP resulted in excellent selectivity of the sensor for the ALP assay in human serum, yielding a high recovery rate and a high precision of 99.2 ± 1.5 % for the standard addition method.

Smartphone-assisted point-of-care colorimetric biosensor for the detection of urea via pH-mediated AgNPs growth.

Smartphone-assisted point-of-care (POC) bioassay has brought a giant leap in personal healthcare system and environmental monitoring advancements. In this study, we developed a rapid and reliable colorimetric urea biosensor assisted by a smartphone. We employed hydrolysis of urea into NH3 by urease, which activates the reduction power of tannic acid, to generate silver nanoparticles for a dramatic colorimetric response. The proposed urea biosensor was validated in a solution to provide high selectivity against various interferents in human urine. It had high sensitivity, with a limit of detection as low as 0.0036 mM, and a high reliability of 99% ± 2.9% via the standard addition method. The urea biosensor was successfully implanted on a paper to facilitate smartphone-assisted POC readout with a limit of detection of 0.58 mM and wide detection range of 500 mM, whereby direct diagnosis of human urine without dilution was realized. Our smartphone-assisted POC colorimetric urea biosensor will pave the way for daily monitoring systems of renal and hepatic dysfunction diseases.

Dual-Surfactant-Capped Ag Nanoparticles as a Highly Selective and Sensitive Colorimetric Sensor for Citrate Detection.

A colorimetric sensor for the detection of citrate ions is reported here using dual-surfactant-capped Ag nanoparticles (dual-AgNP sensor). A mixture of cetyl trimethyl ammonium bromide and a newly prepared gemini nonionic (GFEO) surfactant was used as a capping agent to synthesize dual-surfactant-capped Ag NPs for selective and sensitive citrate detection. The GFEO surfactant was designed with a specific chemical structure to provide strong binding with citrate for selective and sensitive detection. The developed dual-AgNP sensor showed extremely high selectivity toward citrate even in the presence of interfering species. Quantitative detection of citrate was carried out based on the changes in UV-vis absorbance and naked-eye readout. After optimization, the dual-AgNP sensor exhibited a visual detection limit of 25 µM and a low limit of detection of 4.05 nM with a UV-vis spectrometer. The developed citrate sensor performed well with a urine sample, with a high recovery of 99.6%. The prepared solution sensor was constructed on a paper-based analytical device.

Synthesis of anionic chitosan surfactant and application in silver nanoparticles preparation and corrosion inhibition of steel.

Three anionic chitosan surfactant with different hydrophobic tails labeled Chitosan-R8, Chitosan-R12 and Chitosan-R16 were prepared and their surface behavior in aqueous solution was determined by surface tension measurements at three different temperatures 20, 40 and 60 °C. The affinity of the synthesized anionic chitosan surfactant to form micelle enhanced with increasing the hydrophobic chain length as well as raising the solution temperature up to 60 °C. The anionic chitosan surfactant showed a great influence as capping agent for the in-situ preparation of silver nanoparticles (AgNPs) based on photochemical reduction method using sunlight as reducing agent. The chemical structure of chitosan surfactant showed a great effect on the size and stability of the prepared AgNPs. The Chitosan-R16 with longer hydrophobic tail, produce a uniform, small size & stable AgNPs compared to shorter tail Chitosan-R12 & Chitosan-R8. The prepared anionic chitosan showed good inhibiting effect against the steel corrosion in the 1.0 M HCl. The corrosion inhibition efficiency was determined using three different techniques, proving the ability of the new chitosan surfactant to inhibit the steel corrosion. The XPS results confirmed the formation of chitosan inhibitor on the steel surface.

Prevalence, Predictors, and Characteristics of Waterpipe Smoking Among Jazan University Students in Saudi Arabia: A Cross-Sectional Study.

Background: Waterpipe smoking (WPS), also called shisha, has considerable short and long-term effects on human health. WPS has become increasingly popular among the youth in Jazan society. Hence, this study is aimed to assess the prevalence, predictors, and characteristics (knowledge and attitude) of WPS among male and female students at Jazan University. Methods and materials: A descriptive, cross-sectional study was conducted among 405 students. Data were collected using a self-administered validated questionnaire. The prevalence and predictors of WPS and the association between important socio-demographic factors (sex, type of college, parents smoking, home mate smoking and close friend smoking) were studied. Results: The prevalence of WPS among students was high, approximately 34.0%. The prevalence rate was significantly higher in males (42.5%, n = 74) than in females (27.0%, n = 57) (p = 0.001). The main predictors of WPS were: being male (OR = 1.99, 95% CI [1.30, 3.06], p = 0.001), believing that shisha smoking is less harmful & addictive than cigarettes (OR = 3.84, 95% CI [1.88, 7.83], p < 0.001 and 3.80, 95% CI [2.0, 7.11], p < 0.001, respectively), and having a close friend who smokes (OR = 6.85, 95% CI [3.84, 12.22], p < 0.001). Conclusions: WPS prevalence among Jazan University students was high, and the most influential factors were being male, having smoker housemates and friends, and having incorrect thoughts and beliefs.

Studying the silver nanoparticles influence on thermodynamic behavior and antimicrobial activities of novel amide Gemini cationic surfactants.

Three novels amide Gemini cationic surfactants with various alkyl chains and their silver nanohybrid with silver nanoparticles were synthesized and a confirmation study for surfactant and their nanoparticles formation has been established using IR, 1HNMR, TEM and UV-Vis spectroscopy. The surface-active properties of these surfactants and their nanoform were investigated through surface tension and electrical conductivity measurements and a comparative study has been established. The thermodynamic parameters of micellization and adsorption were assessed at temperatures range from 25 to 65°C. The effect of silver particles on the surface behavior of the synthesized surfactant has been discussed. The aggregation behavior of silver nanoparticles with these synthesized Gemini surfactants in water were investigated using dynamic light scattering and transmission electron microscopy. Furthermore, the antimicrobial activities of these synthesized amide Gemini surfactants and their nanostructure with silver against both Gram positive and Gram negative bacteria were also investigated.