Updates in<i>SASfit</i>for fitting analytical expressions and numerical models to small-angle scattering patterns

Kohlbrecher, J.; Breßler, Ingo

doi:10.1107/s1600576722009037

“…We also compare the output from the various versions of “ P ( q ) and S ( q ) CREASE” to analytical model fits using the open-source commonly used scattering fitting software package SASfit. , The analytical modeling is performed by fitting a P ( q ) model and an S ( q ) model. For the S ( q ) model, we select the sticky hard sphere model. ,, For the P ( q ) model, we consider two core–shell models; one assumes a polydisperse core size and constant shell thickness, and the other assumes a constant core size and polydisperse shell thickness.…”

Section: Resultsmentioning

confidence: 99%

“…We also compare the output from the various versions of “ P ( q ) and S ( q ) CREASE” to analytical model fits using the open-source commonly used scattering fitting software package SASfit. 69 , 70 The analytical modeling is performed by fitting a P ( q ) model and an S ( q ) model. For the S ( q ) model, we select the sticky hard sphere model.…”

Section: Resultsmentioning

confidence: 99%

Computational Reverse-Engineering Analysis for Scattering Experiments for Form Factor and Structure Factor Determination (“P(q) and S(q) CREASE”)

Heil

¹

,

Ma

²

,

Bharti

³

et al. 2023

JACS Au

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In this paper, we present an open-source machine learning (ML)-accelerated computational method to analyze small-angle scattering profiles [ I ( q ) vs q ] from concentrated macromolecular solutions to simultaneously obtain the form factor P ( q ) ( e.g ., dimensions of a micelle) and the structure factor S ( q ) ( e.g ., spatial arrangement of the micelles) without relying on analytical models. This method builds on our recent work on Computational Reverse-Engineering Analysis for Scattering Experiments (CREASE) that has either been applied to obtain P ( q ) from dilute macromolecular solutions (where S ( q ) ∼1) or to obtain S ( q ) from concentrated particle solutions when P ( q ) is known ( e.g ., sphere form factor). This paper’s newly developed CREASE that calculates P ( q ) and S ( q ), termed as “ P ( q ) and S ( q ) CREASE”, is validated by taking as input I ( q ) vs q from in silico structures of known polydisperse core(A)–shell(B) micelles in solutions at varying concentrations and micelle–micelle aggregation. We demonstrate how “ P ( q ) and S ( q ) CREASE” performs if given two or three of the relevant scattering profiles— I total ( q ), I A ( q ), and I B ( q )—as inputs; this demonstration is meant to guide experimentalists who may choose to do small-angle X-ray scattering (for total scattering from the micelles) and/or small-angle neutron scattering with appropriate contrast matching to get scattering solely from one or the other component (A or B). After validation of “ P ( q ) and S ( q ) CREASE” on in silico structures, we present our results analyzing small-angle neutron scattering profiles from a solution of core–shell type surfactant-coated nanoparticles with varying extents of aggregation.

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“…q scattering curves were corrected by the subtraction of the scattering of the pure solvent. The fitting procedures were performed using the SASfit software …”

Section: Methodsmentioning

confidence: 99%

“…The fitting procedures were performed using the SASfit software. 37 Determination of RhB Loading Efficiency. The values of RhB loading efficiency were calculated as the ratio between the RhB amount determined in the polymersome formulations and the RhB feeding.…”

Section: Cryo-transmission Electron Microscopymentioning

confidence: 99%

Role of Membrane Features on the Permeability Behavior of Polymersomes and the Potential Impacts on Drug Encapsulation and Release

Oliveira

¹

,

Batista

²

,

Černoch

³

et al. 2023

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Self-assembled bilayer structures such as those produced from amphiphilic block copolymers (polymersomes) are potentially useful in a wide array of applications including the production of artificial cells and organelles, nanoreactors, and delivery systems. These constructs are of important fundamental interest, and they are also frequently considered toward advances in bionanotechnology and nanomedicine. In this framework, membrane permeability is perhaps the most important property of such functional materials. Having in mind these considerations, we herein report the manufacturing of intrinsically permeable polymersomes produced using block copolymers comprising poly[2-(diisopropylamino)-ethyl methacrylate] (PDPA) as the hydrophobic segment. Although being water insoluble at pH 7.4, its pK a(PDPA) ∼ 6.8 leads to the presence of a fraction of protonated amino groups close to the physiological pH, thus conducting the formation of relatively swollen hydrophobic segments. Rhodamine B-loaded vesicles demonstrated that this feature confers inherent permeability to the polymeric membrane, which can still be modulated to some extent by the solution pH. Indeed, even at higher pH values where the PDPA chains are fully deprotonated, the experiments demonstrate that the membranes remain permeable. While membrane permeability can be, for instance, regulated by introducing membrane proteins and DNA nanopores, examples of membrane-forming polymers with intrinsic permeability have been seldom reported so far, and the possibility to regulate the flow of chemicals in these compartments by tuning block copolymer features and ambient conditions is of due relevance. The permeable nature of PDPA membranes possibly applies to a wide array of small molecules, and these findings can in principle be translocated to a variety of disparate bio-related applications.

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“…The SASFit software (Breßler et al, 2015a;Kohlbrecher & Breßler, 2022) allows the calculation of scattered intensity for isolated spheroids. Fig.…”

Section: Isolated Spheroidsmentioning

confidence: 99%

Small-angle X-ray scattering intensity of multiscale models of spheroids

Duchêne

¹

,

Humbert

²

,

Sorbier

³

et al. 2023

J Appl Cryst

1

0

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The microstructure of heterogeneous catalysts often consists of multiscale aggregates of nanoparticles, some of which are highly anisotropic. Therefore, small-angle X-ray scattering, in classical or anomalous mode, is a valuable tool to characterize this kind of material. Yet, the classical exploitation of the scattered intensities through form and structure factors or by means of Boolean models of spheres is questionable. Here, it is proposed to interpret the scattered intensities through the use of multiscale Boolean models of spheroids. The numerical procedure to compute scattered intensities of such models is given and then validated on asymptotic diluted Boolean models, and its applicability is demonstrated for the characterization of alumina catalyst supports.

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Updates inSASfitfor fitting analytical expressions and numerical models to small-angle scattering patterns

Cited by 33 publications

References 119 publications

Computational Reverse-Engineering Analysis for Scattering Experiments for Form Factor and Structure Factor Determination (“P(q) and S(q) CREASE”)

Computational Reverse-Engineering Analysis for Scattering Experiments for Form Factor and Structure Factor Determination (“P(q) and S(q) CREASE”)

Role of Membrane Features on the Permeability Behavior of Polymersomes and the Potential Impacts on Drug Encapsulation and Release

Small-angle X-ray scattering intensity of multiscale models of spheroids

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