Ms for Investigation of Time-Dependent Protein Adsorption On Surfaces in Complex Biological Samples

Abstract

Aim:This study aims at developing a nondestructive way for investigating protein adsorption on surfaces such as biomaterials using mass spectrometry.Methods:Ventricular cerebrospinal fluid in contact with poly carbonate membranes were used as adsorption templates and on-surface enzymatic digestion was applied to desorb proteins and cleave them into peptides. Mass spectrometric analysis provided both protein identification and determination of protein specific adsorption behavior.Results:In general, the adsorption increased with incubation time but also protein-specific time-resolved adsorption patterns from the complex protein solution were discovered.Conclusion:The method developed is a promising tool for the characterization of biofouling, which sometimes causes rejection and encapsulation of implants and can be used as complement to other surface analytical techniques.

Mass Spectrometric Determination of the Effect of Surface Deactivation on Membranes Used for In-Situ Sampling of Cerebrospinal Fluid (CSF)

“…Ventricular CSF was collected and measured for total protein concentration as described by Undin et al [7]. Briefly, CSF from neurointensive care patients with invasive intracranial pressure monitoring owing to severe spontaneous subarachnoid hemorrhage was collected by ventricular drainage and pooled together.…”

“…Protein adsorption experiments were performed as described by Undin et al [7]. Briefly, 18 membranes were clamped to 6 holders, resulting in 3 membranes per holder.…”

“…Peptides were desalted using C18-based solid phase extraction (SPE) columns according to standard procedures and dried down. The oSED is described in detail by Undin et al [7,8].…”

“…The LC-MS/MS analysis was performed as described by Undin et al [7]. Briefly, in-house packed C18-AQ nano-columns with integrated emitter were used either with an Agilent 1100 converted nano-LC (Agilent Technologies, Santa Clara, CA, USA) system connected to a 7 T hybrid linear in trap Fourier Transform-Ion Cyclotron Resonance (LTQ-FTICR) Ultra MS (Thermo, Thermo Fisher Scientific, Bremen, Germany) or with a nano-LC (EASY-nLC II, Thermo) system connected to a LTQ Orbitrap Velos Pro (Thermo).…”

“…Thus, the evaluation of the membranes is performed in a model system as close to reality as possible. We use the developed, straight forward, and gentle on-surface enzymatic digestion (oSED) protocol [7,8], in which proteins were digested with trypsin while still adsorbed to the membrane. The resulting peptides were collected and analyzed using shotgun proteomics with nano-liquid chromatography and tandem mass spectrometry (LC-MS/MS).…”