Controlling orientation, conformation, and biorecognition of proteins on silane monolayers, conjugate polymers, and thermo-responsive polymer brushes: investigations using TOF-SIMS and principal component analysis

Katarzyna Gajos,Andrzej Budkowski,Kamil Awsiuk

doi:10.1007/s00396-020-04711-7

Katarzyna Gajos, Andrzej Budkowski + Show 1 more

Open Access

https://doi.org/10.1007/s00396-020-04711-7

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Journal: Kolloid-Zeitschrift	Publication Date: Aug 16, 2020
Citations: 15	License type: open-access

Affiliation: Jagiellonian University, Institute of Physics

Abstract

Control over orientation and conformation of surface-immobilized proteins, determining their biological activity, plays a critical role in biointerface engineering. Specific protein state can be achieved with adjusted surface preparation and immobilization conditions through different types of protein-surface and protein-protein interactions, as outlined in this work. Time-of-flight secondary ion mass spectroscopy, combining surface sensitivity with excellent chemical specificity enhanced by multivariate data analysis, is the most suited surface analysis method to provide information about protein state. This work highlights recent applications of the multivariate principal component analysis of TOF-SIMS spectra to trace orientation and conformation changes of various proteins (antibody, bovine serum albumin, and streptavidin) immobilized by adsorption, specific binding, and covalent attachment on different surfaces, including self-assembled monolayers on silicon, solution-deposited polythiophenes, and thermo-responsive polymer brushes. Multivariate TOF-SIMS results correlate well with AFM data and binding assays for antibody-antigen and streptavidin-biotin recognition. Additionally, several novel extensions of the multivariate TOF-SIMS method are discussed.Graphical abstract

Highlights

Protein immobilization on a solid surface is essential for the development of biotechnological applications covering a wide range of areas, such as medical diagnostic, pollution screening, regenerative medicine, or drug delivery
Information about the state, i.e., the conformation and orientation, of different proteins immobilized on various molecular and polymer surfaces are readily provided by the multivariate TOFSIMS method, which combines an excellent chemical specificity with surface sensitivity
The determined conformation changes of immobilized protein are confirmed by atomic force microscopy (AFM) morphology images of protein coverage, modified by denaturation (Fig. 5)

Summary

Introduction

Protein immobilization on a solid surface is essential for the development of biotechnological applications covering a wide range of areas, such as medical diagnostic, pollution screening, regenerative medicine, or drug delivery. Conjugated backbones and alkyl side chains, accessed by TOF-SIMS, correspond to the amorphous morphology of P3ATs and to the edge-on textured crystallites of RP3ATs, respectively Such a crystalline order (increasing along with the series P3BT < RP3HT < RP3BT < PQT12 [35, 77]) can affect protein conformation (Fig. 5) and improve the electrostatic interactions that control protein orientation The impact of the edge-on textured crystallinity of electroactive polythiophene on a protein’s orientation and biorecognition is examined for two proteins, the IgG antibody (Fig. 6) and streptavidin (Fig. 7), adsorbed to two series of solution-deposited polymers with an increasing crystalline order, P3BT < RP3HT < RP3BT [35] (Fig. 6) and P3BT < RP3HT < PQT12 [77] (Fig. 7) For both adsorbed proteins, multivariate PCA analysis of the protein mass signals separates the samples according to the increasing crystallinity of the polymer substrate

Summary and conclusions

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