In this paper, we describe a novel fabrication method of a microfluidic integrated surface plasmon resonance (SPR) gold chip based on a (3-mercaptopropyl) trimethoxy silane (MPTMS) self-assembled monolayer. This monolayer was formed at the surface of a microfluidic chip made of polydimethylsiloxane (PDMS). Its presence was confirmed by contact angle and Fourier transform infrared spectroscopy measurements on the modified PDMS surface. A basic, but nevertheless appropriate, 4-channel microfluidic system was made on PDMS and reported on a gold SPR sensor. Sealing tests were carried-out by injecting continuous flows of solutions under gradient pressure up to 1.8 bar. Bonding strength of chemical and corona binding were measured and compared. The test of the integrated microfluidic SPR sensor on an SPR bench validated its functionality and proved as well that no leakage is observed between the different microfluidic channels.

Surface plasmon resonance (SPR) sensing is a well-established high-sensitivity, label-free and real-time detection technique for biomolecular interaction study. Its primary working principle consists of the measurement of the optical refractive index of the medium that is in close vicinity of the sensor surface. Bio-functionalization techniques allow biomolecular events to be located in such a way. Since optical refractive indices of any medium varies with the temperature, the place where the measurement takes place shall be within a temperature-controlled environment in order to ensure any temperature fluctuation is interpreted as a biomolecular event. Since the SPR measurement probes the sensed medium within the penetration depth of the plasmonic wave, which is less or in the order of 1 µm, we propose to use the metallic film constituting the detection surface as a localized heater aiming at controlling finely and quickly the temperature of the sensed medium. The Joule heating principle is then used and the modeling of the heater is reported as well as its validation by thermal IR imaging. Using water as a demonstration medium, SPR measurement results at different temperatures are successfully compared to the theoretical optical refractive index of water versus temperature.

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Background: Anaemia is almost universal in haemodialysis patients. Here, we evaluated the utility and clinical implications of the commonly employed tests in assessing iron status in haemodialysis patients.Methods: In this prospective observational study, we enrolled 100 prevalent haemodialysis patients, and measured transferrin saturation (TSAT) and serum ferritin at enrolment. Patients were categorized to have normal, deficient, overload, or indeterminate status of iron based on KDOQI guidelines. To study anaemia trend, haemoglobin (Hb) level at time of enrolment, as well as levels 3-months before and 3-months after enrolment, were collected. Patient survival outcomes were also obtained till October 2016.Results: Using serum ferritin and TSAT, iron status was determinable in 48% of the patients ie 20%-normal iron status, 25% - iron deficiency, 3% - iron overload. Fifty-two percent of the patients’ iron status was indeterminate by current parameters. In spite of being on standard-of-care treatment in our centre, we observed that mean-Hb level of patients in the indeterminate group showed insignificant increases compared to normal- and deficient-groups. Mean delta-Hb levels over 6-months were 0.80±1.54 g/dl in the indeterminate group, compared to 1.87±1.95 g/dl in the deficient group (P=0.03). In our cohort, 57% had died and 5 lost follow-ups during the study (P=0.30 between groups).Conclusions: Serum ferritin and TSAT accurately categorized the iron status of 48% haemodialysis patients in our study. Divergent serum ferritin and TSAT values, or an iron indeterminate state was prevalent in 52% of our urban dialysis cohort. The indeterminate group had inferior increases in Hb over time with current treatment, showing clinical relevance of this finding. Our data suggests the need for more sensitive indices to accurately assess iron status, and improve anaemia management.