DOI: 10.15125/bath-01635
title: Dataset for "Influence of Block Microstructure on the Interaction of Styrene-Maleic Acid Copolymer Aggregates and Lipid Nanodiscs"

description: Copolymers between styrene and maleic acid are able to extract membrane proteins directly from cells, reconstituting lipid membranes into nanodiscs. RAFT copolymerisation was used to generate copolymers of equivalent molecular mass but inverted block sequences and end group termini. This dataset contains characterisation data for the copolymers (GPC, NMR, FTIR, UV-vis), included deuterated variants for neutron scattering experiments, as well as the structures formed in solution. Aggregates were assed by a combination of DLS and surface tension measurements, and nanodisc formation kinetics through UV-vis using both model DMPC vesicle and E.coli membrane suspensions. It was found that mismatched hydrophilic and hydrophobic end groups on the respective styrene block and alternating block, impeded membrane solubilisation. This highlights not only how the amphiphilic balance of these blocks is important for efficient nanodisc formation, but also how end groups influence these and may be optimised towards the extraction of more challenging MPs.
description: Data collection methods are described in full in the publication "Influence of Block Microstructure on the Interaction of Styrene-Maleic Acid Copolymer Aggregates and Lipid Nanodiscs". Briefly, various copolymers between styrene and maleic anhydride were prepared by RAFT polymerisation, which, when using DDMAT, results in a relatively-large and hydrophobic SC12 end group (SMAnh-SC12). This block sequence was then inverted by first synthesising a poly(sty) macro-RAFT agent, from which a Sty:MA alternating block may be polymerised. A commercial variant, SMA2000, synthesised by free-radical polymerisation was also used for comparison. All copolymers were then hydrolysed to the acid form (SMA) before workup and purification.
description: 1H and 13C NMR: 
 Spectra were analysed using Mestrelab MNova 11.0 software where spectra were baseline corrected and line broadening used to allow accurate integration of peak area. 
 
 GPC: 
 Chromatograms were analysed in Agilent GPC/SEC software to extract Mn and PDI values.
 
 UV-vis: 
 The presence of the SC12 end group can be monitored by the peak at 310 nm in UV-vis spectra. Resultant spectra were normalised by the styrenic absorbance peak at 262 nm.
description: FTIR: 
 FTIR measurements were conducted on a Perkin Elmer ATR desktop spectrometer with solid-state polymer samples at room temperature. 
 
 1H & 13C NMR: 
 1H and 13C NMR spectra were recorded on an Agilent 500 MHz spectrometer at room temperature using d6-acetone (for anhydride species) or D2O (for acid species) as the solvent. 
 
 GPC: 
 GPC was conducted using an Agilent GPC 1260 Infinity chromatograph using two PLgel 5μM MIXED-D 30 cm x 7.5 mm columns with a guard column PLgel 5 μm MIXED Guard 50 x 7.5 mm. The column oven was maintained at 35 °C, with GPC-grade THF as the eluent at a flow rate of 1.00 mL/min and refractive index detection and polymer concentrations between 1.0 – 2.0 mg/mL. The system was calibrated against 12 narrow molecular weight polystyrene standards with a range of Mw from 1050 Da to 2650 kDa. 
 
 DLS: 
 DLS was conducted using a Malvern Zetasizer Nanoseries at theta = 173 degrees (backscattering) and wavelength = 633 nm. 
 
 Pendant Drop Tensiometry: 
 Tensiometry was conducted on a FTA 1000 contact angle/surface tension analyser and processed using FTA 32 surface tension image analysis software. Syringe needles were prepared by extensive washing before SMA polymers in PBS at variant concentrations were passed through these to produce a small hanging droplet which was imaged at a typical rate of 10 images per second for 10 seconds. 
 
 SANS: 
 SANS was performed at the ISIS Neutron and Muon Source (Rutherford Appleton Laboratory, Didcot, UK), on the SANS2D instrument (doi:10.5286/ISIS.E.RB2010215), using 1 mm quartz Hellma cells at 25 °C.  Prior to experiments, samples were mounted in a temperature controlled multi-position sample changer. Data were subsequently reduced using Mantid software and the varying solution contrasts simultaneously fit using the NIST SANS analysis package within IgorPro.