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Understanding the determinants of permeability and selectivity in biological channels serves two general purposes. It provides fundamental biophysical insights and allows the evaluation of new membrane proteins and artificial channel designs for the development of biomimetic separation membranes. This understanding relies on accurate ways to quantify unitary (single channel) solute and solvent permeabilities. However, the current research in biomimetic and bioinspired membranes and in protein biophysics tends to focus on relative permeabilities. Further, many methods and approximations currently used result in erroneous permeability values which hinder and complicate the comparison between channels. Combined, these gaps in the available measurements obscure the biophysical insights and impede the development of novel high-performance channels. In this review, we summarize in vitro model membrane systems useful to functionally characterize artificial as well as biological channels. We also critically discuss biophysical techniques capable of extracting permeability values and membrane channel densities, which are fundamental parameters required to determine accurate unitary permeability values. Pertinent examples are provided, along with advantages, disadvantages, and potential improvements needed for specific techniques to acquire accurate unitary permeability values for a diverse set of small molecules, including water, ions, weak acids and bases, neutral molecules, and protons. Version of record

The endeavors to understand the determinants of water permeation through membrane channels, the effect of the lipid or polymer membrane on channel function, the development of specific water flow inhibitors, the design of artificial water channels and aquaporins for the use in industrial water filtration applications all rely on accurate ways to quantify water permeabilities (Pf). A commonly used method is to reconstitute membrane channels into large unilamellar vesicles (LUVs) and to subject these vesicles to an osmotic gradient in a stopped-flow device. Fast recordings of either scattered light intensity or fluorescence self-quenching signals are taken as a readout for vesicle volume change, which in turn can be recalculated to accurate Pf values. By means of computational and experimental data, we discuss the pros and cons of using scattering versus self-quenching experiments or subjecting vesicles to hypo- or hyperosmotic conditions. In addition, we explicate for the first time the influence of the LUVs size distribution, channel distribution between vesicles and remaining detergent after protein reconstitution on Pf values. We point out that results such as the single channel water permeability (pf) depend on the membrane matrix or on the direction of the applied osmotic gradient may be direct results of the measurement and analysis procedure., Accurate pf values are of utmost importance to understand the structure–function relationship of water permeation through membrane channels, guiding the design of artificial or biological water channels for separation applications.

BACKGROUND: Radiofrequency identification (RFID) technology is emerging as one of the most pervasive computing technologies due to its broad applicability. Storage of red blood cells (RBCs) is a routine procedure worldwide. Depending on the additive solution, RBCs can be stored at 4 ± 2°C up to 49 days. To support the decision of discarding or further using a blood product, temperature measurement of each unit could be provided by RFID application. The safety evaluation of RFID devices was demonstrated in a regulatory agency required study. It has been concluded in limit tests that high frequency–based RFID technology performed safely for blood products; therefore, a longer exposure of radiofrequency (RF) energy on blood units was performed in this study to detect any biologic effects in RBC samples. STUDY DESIGN AND METHODS: Buffy coat–depleted, in line–filtered RBCs were used as standard products in all tests. Various variables like pH, potassium, glucose, lactate, hemoglobin (Hb), hematocrit, free Hb, and hemolysis rate were measured in a test group with RFID tags placed on their surface and continuously radiated with 13.56-MHz RFID reader radiation for 42 days while stored at 4 ± 2°C and compared to a control group by two-sample t test. RESULTS: In both groups glucose and pH levels decreased while lactate, free Hb, and potassium increased within the expected levels. The hemolysis rate showed increase after the 25th day but remained below the maximum acceptable threshold of 0.8%. CONCLUSION: It is feasible to implement RFID-enabled processes, without detecting any known biologic effects of longer exposure of RF energy on the quality of RBCs.

Ten of thousands patients die every year because of medical errors. Many more patients suffer permanent damage and have to be medicated for the rest of their life. In the context of a blood donation, blood production and blood transfusion process, a lack of consistent and complete trace and tracking of individual blood bags has been identified as a source of medical errors. This research aims to address this challenge to help organisations such as blood banks to track the donation, manufacture, distribution and in-use of blood products, to remove/minimise the potential medical errors. Although the major goal of this research study is to increase patient security, reduction of wastage is also part of the research aims because donated blood is a scarce resource. Nowadays, up to 20% of the blood bags are put to scrap without use and each of the blood bag costs 220 Euro to produce (i.e. from collection, production and storage until it is consumed/discarded). In Austria alone, 5.6 million Euros could be saved each year if the wastage can be removed. Besides the economic issue, donated human blood is a scarce resource and always gives a poor psychological response from the general public when preventable wastage occurs. This research study approaches the challenges through a life-cycle point of view because it sees the goal can only be achieved through ‘real-time’ life-cycle information that governs the quality and life-span of such products. As a result, a new RF based semi-active transponder (13.56 MHz, ISO 15693 compatible HF interface) with integrated data storage and temperature sensor, which is able to sustain high g - forces have been developed to provide the ‘real-time’ temperature data and other related information support. The developed life-cycle information system has been trialled at the University Clinic of Graz not only to test its effectiveness, but also used as a case study for this research study. Due to the resources constraints (e.g. time), the case study does not create sufficient data to establish any statistical significance to quantify the benefits of the proposed systems. However, all the involved persons including both the operational and professional staff at University Clinique of Graz, have agreed the proposed RFID transponders, together with its lifecycle management system provides better decision support to handle individual blood bag at any stage of its lifecycle. They believe the proposed system will improve patients’ safety and reduce the wastage of blood bags. During the trail, it happened that two blood bags ready for transfusion were detected to be below 0°C somehow during their life-cycle. A blood transfusion would have been 100% mortal to the patients. The detection of this fatal mistake did save at least the life of one human being and illustrated the importance of an objective, overarching and complete life-cycle system for blood products. Although this research is focused on blood products for blood banks and medical environments, the benefits of the system approach and methodologies could also apply to other types of sensitive and fragile goods that require life-cycle information support.

Radiofrequency identification (RFID) technology is emerging as one of the most pervasive computing technologies due to its broad applicability. Storage of red blood cells (RBCs) is a routine procedure worldwide. Depending on the additive solution, RBCs can be stored at 4 ± 2°C up to 49 days. To support the decision of discarding or further using a blood product, temperature measurement of each unit could be provided by RFID application. The safety evaluation of RFID devices was demonstrated in a regulatory agency required study. It has been concluded in limit tests that high frequency-based RFID technology performed safely for blood products; therefore, a longer exposure of radiofrequency (RF) energy on blood units was performed in this study to detect any biologic effects in RBC samples.Buffy coat-depleted, in line-filtered RBCs were used as standard products in all tests. Various variables like pH, potassium, glucose, lactate, hemoglobin (Hb), hematocrit, free Hb, and hemolysis rate were measured in a test group with RFID tags placed on their surface and continuously radiated with 13.56-MHz RFID reader radiation for 42 days while stored at 4 ± 2°C and compared to a control group by two-sample t test.In both groups glucose and pH levels decreased while lactate, free Hb, and potassium increased within the expected levels. The hemolysis rate showed increase after the 25th day but remained below the maximum acceptable threshold of 0.8%.It is feasible to implement RFID-enabled processes, without detecting any known biologic effects of longer exposure of RF energy on the quality of RBCs.