1
|
Sato T, Dunderdale GJ, Hozumi A. Threshold of Surface Initiator Concentration for Polymer Brush Growth by Surface-Initiated Atom Transfer Radical Polymerization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:480-488. [PMID: 38127729 DOI: 10.1021/acs.langmuir.3c02756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The surface modification of various materials by grafting functional molecules has attracted much attention from fundamental research to practical applications because of its ability to impart various physical and chemical properties to the surfaces. One promising approach is the use of polymer brushes synthesized by atom transfer radical polymerization (ATRP) from surface-tethered initiators (SIs). In this study, for the purpose of controlling the grafting amounts/densities of polymer brushes, we developed a facile method to precisely regulate SI concentrations of SI layers (SILs) by serial dilution based on a sol-gel method. By simply mixing organosilanes terminated with and without an initiator group ((p-chloromethyl) phenyltrimethoxysilane (CMPTMS) and phenyltrimethoxysilane (PTMS), respectively) with tetraethoxysilane (TEOS), SI concentrations of SILs could be arbitrarily tuned precisely by varying dilution factors of (CMPTMS + PTMS)/CMPTMS (DFs, 1-107). The resulting SILs prepared at different DFs were highly smooth and transparent. X-ray photoelectron spectroscopy (XPS) also confirmed that the SIs were homogeneously distributed at the topmost surface of the SILs and their concentrations were proven to be accurately and precisely controlled from high to extremely low, comparable to theoretical values. Subsequent SI-ATRP in air ("paint-on" SI-ATRP) of two different types of monomers (hydrophobic/nonionic (2,3,4,5,6-pentafluorostyrene) and hydrophilic/ionic (sodium 4-styrenesulfonate)) demonstrated that polymer brushes with different grafting amounts/densities were successfully grafted only from SILs with DFs of 1-104 (theoretical SI concentrations: 3.9 × 10-4 ∼ 3.5 units/nm2), while at DFs of 105 and above (theoretical SI concentrations: <3.9 × 10-5 units/nm2), no sign of polymer brush growth was confirmed by thickness, XPS, and water contact angle data. Therefore, we are the first to gather evidence that the approximate threshold of SI concentration required for "paint-on" SI-ATRP might be on the order of 10-4 ∼ 10-5 units/nm2.
Collapse
Affiliation(s)
- Tomoya Sato
- National Institute of Advanced Industrial Science and Technology (AIST), 4-205, Sakurazaka, Moriyama, Nagoya 463-8560, Japan
| | - Gary J Dunderdale
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, U.K
| | - Atsushi Hozumi
- National Institute of Advanced Industrial Science and Technology (AIST), 4-205, Sakurazaka, Moriyama, Nagoya 463-8560, Japan
| |
Collapse
|
2
|
Abstract
I review experimental developments in the growth and application of surface-grafted weak polyelectrolytes (brushes), concentrating on their surface, tribological, and adhesive and bioadhesive properties, and their role as actuators.
Collapse
Affiliation(s)
- Mark Geoghegan
- School of Engineering, Newcastle University, Merz Court, Newcastle-upon-Tyne NE1 7RU, UK.
| |
Collapse
|
3
|
Leggett GJ. Tools for Low-Dimensional Chemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:7589-7602. [PMID: 30365897 DOI: 10.1021/acs.langmuir.8b02672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Many biological mechanisms can be considered to be low-dimensional systems: their function is determined by molecular objects of reduced dimensionality. Bacterial photosynthesis is a very good example: the photosynthetic pathway is contained within nano-objects (vesicles) whose function is determined by the numbers and nanoscale organization of membrane proteins and by the ratios of the different types of protein that they contain. Systems biology has provided computational models for studying these processes, but there is a need for experimental platforms with which to test their predictions. This Invited Feature Article reviews recent work on the development of tools for the reconstruction of membrane processes on solid surfaces. Photochemical methods provide a powerful, versatile means for the organization of molecules and membranes across length scales from the molecular to the macroscopic. Polymer brushes are highly effective supports for model membranes and versatile functional and structural components in low-dimensional systems. The incorporation of plasmonic elements facilitates enhanced measurement of spectroscopic properties and provides an additional design strategy via the exploitation of quantum optical phenomena. A low-dimensional system that incorporates functional transmembrane proteins and a mechanism for the in situ measurement of proton transport is described.
Collapse
Affiliation(s)
- Graham J Leggett
- Department of Chemistry , University of Sheffield , Brook Hill, Sheffield S3 7HF , U.K
| |
Collapse
|
4
|
Raftari M, Zhang ZJ, Carter SR, Leggett GJ, Geoghegan M. Salt Dependence of the Tribological Properties of a Surface-Grafted Weak Polycation in Aqueous Solution. TRIBOLOGY LETTERS 2017; 66:11. [PMID: 31983863 PMCID: PMC6951817 DOI: 10.1007/s11249-017-0963-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 11/23/2017] [Indexed: 06/10/2023]
Abstract
The nanoscopic adhesive and frictional behaviour of end-grafted poly[2-(dimethyl amino)ethyl methacrylate] (PDMAEMA) films (brushes) in contact with gold- or PDMAEMA-coated atomic force microscope tips in potassium halide solutions with different concentrations up to 300 mM is a strong function of salt concentration. The conformation of the polymers in the brush layer is sensitive to salt concentration, which leads to large changes in adhesive forces and the contact mechanics at the tip-sample contact, with swollen brushes (which occur at low salt concentrations) yielding large areas of contact and friction-load plots that fit JKR behaviour, while collapsed brushes (which occur at high salt concentrations) yield sliding dominated by ploughing, with conformations in between fitting DMT mechanics. The relative effect of the different anions follows the Hofmeister series, with I- collapsing the brushes more than Br- and Cl- for the same salt concentration.
Collapse
Affiliation(s)
- Maryam Raftari
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH UK
| | - Zhenyu J. Zhang
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF UK
- Present Address: School of Chemical Engineering, University of Birmingham, Birmingham, B15 2TT UK
| | - Steven R. Carter
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH UK
| | - Graham J. Leggett
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF UK
| | - Mark Geoghegan
- Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH UK
| |
Collapse
|
5
|
Kalasin S, Letteri RA, Emrick T, Santore MM. Adsorbed Polyzwitterion Copolymer Layers Designed for Protein Repellency and Interfacial Retention. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13708-13717. [PMID: 29134801 DOI: 10.1021/acs.langmuir.7b03391] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC), when end-tethered to surfaces by the adsorption of copolymeric cationic segments, forms adsorbed layers that substantially reduce protein adsorption. This study examined variations in the molecular architecture of copolymers containing cationic poly(trimethylammonium ethyl methacrylate (pTMAEMA) anchor blocks that adsorbed strongly to negative surfaces. With appropriate copolymer design, the pTMAEMA blocks were shielded, by pMPC tethers, from solution-phase proteins. The most protein-resistant copolymer layers, eliminating fibrinogen and lysozyme adsorption within detectible limits of 0.01 mg/m2, had metrics (the amount of pMPC at the surface and the reduced tether footprint) consistent with the formation of an interfacial polymer brush. The p(TMAEMA-b-MPC) copolymer layers substantially outperformed the protein resistance of surface-polymerized pMPC layers when compared on a per-polyzwitterion-mass basis or on the basis of the scaled tether area. Additionally, p(TMAEMA-b-MPC) copolymer layers offered advantages over the much-studied cationically anchored poly(ethylene glycol) (PEG) graft copolymer system, which forms PEG brushes by the adsorption of a poly l-lysine (PLL) backbone. Although the optimized p(TMAEMA-b-MPC) and PLL-PEG copolymers were similarly fibrinogen-resistant, the cationic protein lysozyme was repelled by pMPC but adhered to the PEG brush via PEG-lysozyme attractions. Additionally, the adsorbed p(TMAEMA-b-MPC) copolymers were not displaced by poly l-lysine homopolymers, which completely displaced the PLL-PEG copolymer to expose a protein-adhesive surface. Thus, the p(TMAEMA-b-MPC) copolymer system comprises a scalable means to produce protein-repellent surfaces, free of the complexities of surface-initiated polymerization and with the advantages of polyzwitterions.
Collapse
Affiliation(s)
- S Kalasin
- Department of Polymer Science and Engineering, University of Massachusetts , 120 Governors Drive, Amherst, Massachusetts 01003, United States
| | - R A Letteri
- Department of Polymer Science and Engineering, University of Massachusetts , 120 Governors Drive, Amherst, Massachusetts 01003, United States
| | - T Emrick
- Department of Polymer Science and Engineering, University of Massachusetts , 120 Governors Drive, Amherst, Massachusetts 01003, United States
| | - M M Santore
- Department of Polymer Science and Engineering, University of Massachusetts , 120 Governors Drive, Amherst, Massachusetts 01003, United States
| |
Collapse
|
6
|
Johnson A, Madsen J, Chapman P, Alswieleh A, Al-Jaf O, Bao P, Hurley CR, Cartron ML, Evans SD, Hobbs JK, Hunter CN, Armes SP, Leggett GJ. Micrometre and nanometre scale patterning of binary polymer brushes, supported lipid bilayers and proteins. Chem Sci 2017; 8:4517-4526. [PMID: 28660065 PMCID: PMC5472033 DOI: 10.1039/c7sc00289k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 04/10/2017] [Indexed: 01/03/2023] Open
Abstract
Binary polymer brush patterns were fabricated via photodeprotection of an aminosilane with a photo-cleavable nitrophenyl protecting group. UV exposure of the silane film through a mask yields micrometre-scale amine-terminated regions that can be derivatised to incorporate a bromine initiator to facilitate polymer brush growth via atom transfer radical polymerisation (ATRP). Atomic force microscopy (AFM) and imaging secondary ion mass spectrometry (SIMS) confirm that relatively thick brushes can be grown with high spatial confinement. Nanometre-scale patterns were formed by using a Lloyd's mirror interferometer to expose the nitrophenyl-protected aminosilane film. In exposed regions, protein-resistant poly(oligo(ethylene glycol)methyl ether methacrylate) (POEGMEMA) brushes were grown by ATRP and used to define channels as narrow as 141 nm into which proteins could be adsorbed. The contrast in the pattern can be inverted by (i) a simple blocking reaction after UV exposure, (ii) a second deprotection step to expose previously intact protecting groups, and (iii) subsequent brush growth via surface ATRP. Alternatively, two-component brush patterns can be formed. Exposure of a nitrophenyl-protected aminosilane layer either through a mask or to an interferogram, enables growth of an initial POEGMEMA brush. Subsequent UV exposure of the previously intact regions allows attachment of ATRP initiator sites and growth of a second poly(cysteine methacrylate) (PCysMA) brush within photolithographically-defined micrometre or nanometre scale regions. POEGMEMA brushes resist deposition of liposomes, but fluorescence recovery after photobleaching (FRAP) studies confirm that liposomes readily rupture on PCysMA "corrals" defined within POEGMEMA "walls". This leads to the formation of highly mobile supported lipid bilayers that exhibit similar diffusion coefficients to lipid bilayers formed on surfaces such as glass.
Collapse
Affiliation(s)
- Alexander Johnson
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
| | - Jeppe Madsen
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
| | - Paul Chapman
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
- Department of Physics and Astronomy , University of Sheffield , Sheffield S3 7RH , UK
| | - Abdullah Alswieleh
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
| | - Omed Al-Jaf
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
| | - Peng Bao
- Molecular and Nanoscale Physics Group , School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , UK
| | - Claire R Hurley
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
| | - Michaël L Cartron
- Department of Molecular Biology and Biotechnology , University of Sheffield , Western Bank , Sheffield S10 2TN , UK
| | - Stephen D Evans
- Molecular and Nanoscale Physics Group , School of Physics and Astronomy , University of Leeds , Leeds LS2 9JT , UK
| | - Jamie K Hobbs
- Department of Physics and Astronomy , University of Sheffield , Sheffield S3 7RH , UK
- Krebs Institute , University of Sheffield , Sheffield , South Yorkshire S10 2TN , UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology , University of Sheffield , Western Bank , Sheffield S10 2TN , UK
| | - Steven P Armes
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
| | - Graham J Leggett
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK .
- Krebs Institute , University of Sheffield , Sheffield , South Yorkshire S10 2TN , UK
| |
Collapse
|