5:00 PM - SM04.04.04
Optimizing Homogeneous Thin Solid Films (HTSFs) from µl-sized Blood Droplets via Hyper-Hydrophilic Coatings (HemaDropTM) for Accurate Compositional Analysis via IBA, XRF and XPS
Nikhil Suresh1,2,3,Saaketh Narayan1,2,3,Sukesh Ram1,2,3,Jack Day1,2,3,Harshini Thinakaran4,2,3,Nicole Herbots1,2,5,Eric Culbertson5,2,6,Francesca Ark7,2,Amber Chow1,Shaurya Khanna1,Karen Kavanagh8
Arizona State University1,MicroDrop Diagnostics LLC2,AccuAngle Analytics LLC3,University of Pennsylvania 4,SiO2 Innovates LLC5,Jacobs Center for Cosmetic Surgery6,American University7,Simon Fraser University8
Current blood diagnostics require ~2-10 milliliters (mL) of blood per test, taking hours, or days, for results. Drawing mLs of blood can induce hospital-acquired anemia (HAA) in premature infants, and in chronically, or critically ill patients. Reducing the volume drawn while increasing analysis speed and accuracy can improve healthcare, and decrease suffering and costs from infections and transfusions. Rapid results from µL blood samples can revolutionize quality and cost of care.
Theranos claimed it could analyze nanoliter (nL) blood droplets. FDA raids triggered by inaccuracies in tests, revealed Theranos diluted nL into mL-sized vials while using standard analysis methods with errors greater than the medically acceptable threshold of 10%.
However, HemaDropTM, [1-4] a “hyper-hydrophilic” surface coating, can solidify micro-liter (µL)-sized blood droplets within minutes microliter-sized droplets into Homogeneous Thin Solid Films (HTSFs), without phase separation or segregation. HTSFs can be analyzed within minutes using handheld or desktop analyzers, in air or in vacuo.
Blood HTSFs were tested for accuracy in measuring electrolytes (Na, K, Mg, Ca, Cl) and hematocrit (Fe) from single µL droplets. So-called “Lytes & Crit” (electrolytes & hematocrit) are often the first tests conducted in ER, ICU, NICU, OR, and hospitals, as general status depends critically on hydration (electrolytes concentration), and oxygenation (Fe hematocrit levels). These are repeated daily and sometimes every few hours.
Repeated measurements show that electrolytes and Fe in human blood are accurate within 10% using IBA, XRF, and XPS, from a few µL of blood solidified as HTSF when calibrated using commercial Balanced Saline Solution (BSS+) pre-solidified on strips coated with HemaDrop™, called DropFilmStrip™ [1-3]
XRF is of particular interest because it is a desktop/handheld tool which yields within minutes compositional analysis within the medically acceptable 10% for Na, K, Mg, Ca, Cl, Fe .
Prior to IBA, XPS, and XRF analysis, congealed, uniform HTSFs are compared to conventionally Dried Blood Spots (DBS). Solidification of droplets into HTSF is observed and timed via optical microscopy and video. In DBS, phase separation between platelets and serum yields rough, non-uniform thin solid films. But HTSFs solidified on HemaDropTM are smooth, and uniform without phase separation. Similar behavior can be seen with solidified Balanced Saline Solution (BSS) droplets. BSS congealed on HemaDropTM exhibits little crystallization and no phase separation while simply dried BSS does.
HTSFs of human blood, canine blood and BSS solidified via HemaDropTM coated surfaces all underwent XRF in air, XPS in 10-10 Torr vacuo, and IBA in 10-7 Torr vacuo, performed on the same set of 5 and 10 µL-sized droplets congealed into HTSFs and compared to DBS.
HTSFs yield identical, reproducible 2 MeV RBS, XPS, and XRF spectra on different areas of HTSFs. C, N, O, Na, K, Ca, Mg, Cl, Fe are detected with leading edges falling within IBA resolution (< 15 keV, 2-3 channels), while DBS yield leading edges spread out over 100 keV.
The damage curve method extrapolates elemental composition while accounting for possible ion damage. Four consecutive spectra are taken on each analyzed area. RBS, XPS and XRF yields are interpolated to 0-analyzing dose to extract original concentrations.
IBA simulations with the software SIMNRA are fitted to the RBS spectra and matched to within 1%. Atomic compositions from sequential IBA, XPS and XRF spectra taken on different areas of HTSFs and on different samples are all within 5%. Relative error analysis between multiple HTSFs establishes reproducibility within 10%. Comparative analysis from these results will be discussed to show how it guides optimization of the technology.
[1-3] Intern. /US Patents Pend. , Herbots N., et al (2016-2018)
[4-6] MRS Advances 2016, 2017, Bio-Interphases (2019)