Biocompatible channels for field-flow fractionation of biological samples: correlation between surface composition and operating performance

Abstract

Biocompatible methods capable of rapid purification and fractionation of analytes from complex natural matrices are increasingly in demand, particularly at the forefront of biotechnological applications. Field-flow fractionation is a separation technique suitable for nano-sized and micro-sized analytes among which bioanalytes are an important family. The objective of this preliminary study is to start a more general approach to field-flow fractionation for bio-samples by investigation of the correlation between channel surface composition and biosample adhesion. For the first time we report on the use of X-ray photoelectron spectroscopy (XPS) to study the surface properties of channels of known performance. By XPS, a polar hydrophobic environment was found on PVC material commonly used as accumulation wall in gravitational field-flow fractionation (GrFFF), which explains the low recovery obtained when GrFFF was used to fractionate a biological sample such as Staphylococcus aureus. An increase in separation performance was obtained first by conditioning the accumulation wall with bovine serum albumin and then by using the ion-beam sputtering technique to cover the GrFFF channel surface with a controlled inert film. XPS analysis was also employed to determine the composition of membranes used in hollow-fiber flow field-flow fractionation (HF FlFFF). The results obtained revealed homogeneous composition along the HF FlFFF channel both before and after its use for fractionation of an intact protein such as ferritin.

Performance of hollow‐fiber flow field‐flow fractionation in protein separation

“…It meant that sample loss during migration was not critical and much can be referred from during the focusing/relaxation process. While it was reported in a recent study, using a PSf HF membrane, that a quite uniform protein layer was found all along the fiber rather than in the focusing zone [18], the current study did not show the same trend according to the observed data for different lengths of HF fibers. This may originate from the difference in the hydrophobicity of membrane materials (PAN HF membrane is more hydrophobic than PSf).…”

“…Resolution achieved in the fractograms of Fig. 2 indicates that the HF FlFFF performance for protein samples is comparable to that which can be obtained using a conventional, flat-channel FlFFF channel [18], except the low separation speed in HF FlFFF. Since _ V V rad = 0.54 mL/min used in the case of the bottom run of Fig.…”

Applications of XPS in bioengineering

“…The multi-element detection, quantification, depth profiling capabilities and high binding energy resolution make it well suited to the examination of a range of both materials commonly used in bioengineering applications (e.g. glass and polystyrene), 6 novel polymer systems 7,8 as well as thin film surface modifications, 9 -13 and native and grown surface oxides.…”

Monitoring of Mixed Culture of Saccharomyces cerevisiae and Acetobacter aceti Using Gravitation Field-flow Fractionation and Gas Chromatography

“…The carrier liquid was water containing 0.1% FL-70 (Fisher Scientific, Loughborough, UK) detergent (a low-foaming; low alkalinity; and phosphate-, chromate-, silicate-free mixture of anionic and nonionic surfactants). Polystyrene (PS) latex beads of various nominal diameters (6,8,12,20, 40 µm) purchased from Duke Scientific Corp. (Palo Alto, CA, USA) were used as standard particles which were dispersed at 0.1%(w/v) in the carrier liquid.…”

“…Field-flow fractionation (FFF) is a separation technique for macromolecules, and can be useful in various fields including biotechnology. [4][5][6] FFF is also well suited to analytical-scale separation and characterization of nano to micron-sized particles. 7,8 FFF has been successfully applied to characterization and separation of colloids with biological interest such as yeast.…”