Krios I-Titan Krios I at Diamond
Krios II-Titan Krios II at Diamond
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Diamond Proposal Number(s):
[31371]
Open Access
Abstract: Magnetotactic bacteria, such as Magnetospirillum gryphiswaldense MSR-1, naturally produce magnetosomes—intracellular magnetic nanoparticles that enable navigation within geomagnetic fields. Magnetosomes hold significant potential for biomedical and biotechnological applications; however, key aspects of their biomineralization remain poorly understood. This study investigates how oxidative stress, induced by hydrogen peroxide and iron, influences magnetosome formation and bacterial physiology under aerobic and microaerobic conditions. Single-cell advanced microscopy and high-throughput techniques revealed that microaerobic conditions supported robust magnetosome production and larger magnetite crystals while maintaining low oxidative stress levels. In contrast, aerobic conditions suppressed magnetosome formation, reduced intracellular iron content, and increased reactive oxygen species (ROS) levels. High extracellular iron enhanced the formation of longer magnetosome chains in microaerobic cultures without causing toxicity but reduced cell viability under aerobic conditions. Hydrogen peroxide exposure caused mild damage and a 25% viability drop in magnetosome-producing cells but led to severe damage and an 80% viability drop in non-magnetosome-producing cells, along with chain fragmentation and smaller magnetite crystals. These results suggest that magnetosome-producing cells exhibit greater resilience to oxidative stress, potentially due to ROS scavenging properties of magnetosomes, and highlight the intricate interplay between oxidative stress, iron regulation, and magnetosome biomineralization. Single-cell analysis revealed heterogeneity in physiological responses, further demonstrating the complexity of these processes. These findings underscore the importance of monitoring physiological changes during production processes to enhance the efficiency and robustness of magnetosome synthesis. The insights gained provide a foundation for improving bioprocesses for large-scale production of high-quality magnetosomes, advancing their applications in biomedicine and biotechnology.
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Dec 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[33098]
Open Access
Abstract: Particle fusion is key for establishing communication between biological components. For this reason, whole cell fusion plays a crucial role in many processes, including infection, muscle formation and tissue repair. Analogous co-assembly between synthetic nanoparticles represents a similar type of communication mechanism in artificial systems. Other approaches to control such co-assembly rely on incorporating anisotropic recognition units onto particle surfaces to provide a thermodynamic driving force. Here we present a fundamentally different approach, where hetero-fusion between two populations of undecorated polymer nanoparticles is regulated using kinetic control. Fusion extent is tuned simply by adjusting polymer chain length. Fusion is probed using an elemental tagging strategy for cryogenic scanning transmission electron microscopy combined with electron energy loss spectroscopy (cryo-STEM-EELS). Our results demonstrate the emergence of a complex process between populations of synthetic nanoparticles akin to communication. We anticipate such systems-level behaviour that results from hetero-fusion can enable future technologies.
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Nov 2025
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labSAXS-Offline SAXS and Sample Environment Development
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Mona
Semsarilar
,
Martin J.
Greenall
,
Alex H.
Balzer
,
Amit Kumar
Sarkar
,
Chaimaa
Gomri
,
Belkacem Tarek
Benkhaled
,
Anke-Lisa
Höhme
,
Martin
Held
,
Volker
Abetz
,
Helena J.
Hutchins-Crawford
,
Georgia L.
Maitland
,
Anisha
Patel
,
Thomas H.
Epps
,
Paul D.
Topham
,
Matthew J.
Derry
Diamond Proposal Number(s):
[29567, 31903]
Open Access
Abstract: We report the combined experimental and theoretical study of the bulk self-assembly behavior of polystyrene-block-poly(2,3,4,5,6-pentafluorostyrene) diblock copolymers. These block copolymers were designed to create highly antagonistic blocks (with a high Flory–Huggins interaction parameter, χ) with minimum disruption to the molecular construct (i.e., only replacing five hydrogen atoms with five fluorine atoms). A large library of diblock copolymers (41 samples) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization to map out a major portion of the phase space. All block copolymers exhibited narrow molecular weight distributions with dispersity (D) values between 1.07 and 1.32, and subsequent thermal annealing revealed phase separation into well-defined nanoscale morphologies depending on their molecular composition, as determined from small-angle X-ray scattering and transmission electron microscopy analyses, with an experimental phase diagram being constructed. The χ value at 25 °C for this block copolymer was estimated to be 0.2 using strong segregation theory, based on trends in phase-separated domain spacing and interfacial width. When applying theoretical approaches, the majority of the domain spacing data trends were captured by a coil–coil diblock copolymer model; however, a better fit to the data for samples with shorter fluorinated blocks was obtained with a rod–coil model, indicating that the chains in these fluorinated blocks likely have a higher inherent stiffness and were thus rod-like. This observation demonstrates that, due to the very high value of χ, a transition from coil–coil to rod–coil behavior can be obtained purely by reducing the length of the stiffer of the two blocks and without varying temperature or the chemical composition of the polymers. This work showcases the presence of strong microphase separation within AB diblock copolymers despite the relatively similar chemical composition of the constituent “A” and “B” units, with a clear transition from rod–coil to coil–coil segregation behavior.
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Oct 2025
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[7249]
Abstract: Despite the potential of poly(2-methacryloyloxy ethyl phosphorylcholine)–poly(2-(diisopropylamino)ethyl methacrylate) (PMPC–PDPA) diblock copolymer nanoparticles for several biological applications, the exact mechanism of pH-induced self-assembly of the PMPC–PDPA chains into nanoparticles remains unclear, although it has been extensively studied by ex situ transmission electron microscopy. Here, we probe this process using time-resolved small-angle X-ray scattering (TR-SAXS) to gain an understanding of the phenomena that occur on the nanoscale. Modeling the TR-SAXS data indicated that spherical micelles and vesicles were formed at a pH as low as 3, and the spherical micelle and vesicle structures reformed at pH 5.5. At pH ∼5.5, insoluble PMPC25–PDPA70 diblock copolymer precipitation was also observed by SAXS. A huge soluble PMPC25–PDPA70 diblock copolymer reservoir might assist in PMPC25–PDPA70 vesicle construction. Additionally, a potential pathway of vesicle construction by spherical micelle fusion was supported by the SAXS evidence.
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Sep 2025
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[39167]
Open Access
Abstract: We report the first reversible addition–fragmentation chain transfer polymerisation-induced self-assembly (RAFT-PISA) in ionic liquid (IL) that proceeds under emulsion conditions. Moreover, this formulation exploits refractive index contrast matching to generate highly transparent nanoparticle dispersions. Specifically, 1-ethyl-3-methyl-imidazolium ethylsulfate, [EMIM][EtOSO3], was used as the solvent for the chain extension of poly(2-hydroxyethyl methacrylate) (PHEMA) macromolecular chain transfer agents (macro-CTAs) using n-butyl methacrylate (BuMA) via RAFT emulsion polymerisation. Two series of PHEMAx-b-PBuMAy diblock copolymers with target PBuMA degrees of polymerisation (DPs) varying from 50 to 1000 were synthesised using either a PHEMA21 or PHEMA77 macro-CTA. All resulting nanoparticle dispersions yielded highly transparent dispersions, even when nanoparticle diameters exceeded 100 nm, due to the closely matched refractive index values of the [EMIM][EtOSO3] solvent and PBuMA nanoparticle core. Detailed analysis using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) confirmed the presence of spherical nanoparticles. Furthermore, the synthesis of PHEMA-b-PBuMA via this new PISA formulation was directly compared to equivalent block copolymer syntheses conducted in N,N-dimethylformamide (DMF) or ethanol/water mixtures. It was found that syntheses conducted in [EMIM][EtOSO3] resulted in the highest monomer conversions (up to >99%) and lowest dispersity (ĐM) values (as low as 1.16) in the shortest reaction times (2 hours) compared to the other solvent systems. This work demonstrates the use of ILs as a more sustainable and effective solvent for RAFT–PISA via the development of the first emulsion PISA formulation in IL.
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May 2025
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B24-Cryo Soft X-ray Tomography
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Diamond Proposal Number(s):
[30471, 33090]
Open Access
Abstract: Iron is a crucial element integral to various fundamental biological molecular mechanisms, including magnetosome biogenesis in magnetotactic bacteria (MTB). Magnetosomes are formed through the internalization and biomineralization of iron into magnetite crystals. However, the interconnected mechanisms by which MTB uptake and regulate intracellular iron for magnetosome biomineralization remain poorly understood, particularly at the single-cell level. To gain insights we employed a holistic multiscale approach, i.e., from elemental iron species to bacterial populations, to elucidate the interplay between iron uptake dynamics and magnetosome formation in Magnetospirillum gryphiswaldense MSR-1 under near-native conditions. We combined a correlative microscopy approach integrating light and X-ray tomography with analytical techniques, such as flow cytometry and inductively coupled plasma spectroscopy, to evaluate the effects of iron and oxygen availability on cellular growth, magnetosome biogenesis, and intracellular iron pool in MSR-1. Our results revealed that increased iron availability under microaerobic conditions significantly promoted the formation of longer magnetosome chains and increased intracellular iron uptake, with a saturation point at 300 μM iron citrate. Beyond this threshold, additional iron did not further extend the magnetosome chain length or increase total intracellular iron levels. Moreover, our work reveals (i) a direct correlation between the labile Fe2+ pool size and magnetosome content, with higher intracellular iron concentrations correlating with increased magnetosome production, and (ii) the existence of an intracellular iron pool, distinct from magnetite, persisting during all stages of biomineralization. This study offers insights into iron dynamics in magnetosome biomineralization at a single-cell level, potentially enhancing the industrial biomanufacturing of magnetosomes.
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Oct 2024
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[37105]
Abstract: Star-shaped block copolymers (SBCs) have sparked interest as efficient cargo carriers due to their high loading capacity, decreased burst effects through sustained release, and maintained stability in dilute aqueous solution. Despite these advantages, the practical usage of SBCs is hindered by their challenging synthesis processes that often utilize metal-based catalysts at high temperatures. Herein we report the tailored synthesis of 3-, 4-, and 6-arm polycaprolactone-b-poly(ethylene glycol), PCL-b-PEG, SBCs using diphenyl phosphate as a friendlier, more sustainable non-metallic catalyst. Nuclear magnetic resonance (NMR) analysis confirms the molecular architecture of SBCs and gel permeation chromatography (GPC) is used to elucidate trends in molar mass when the number of arms within the SBCs is tuned, while dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) studies provide insights into aggregation behavior. Critical aggregation concentration (CAC) values, as measured by fluorescence spectroscopy, demonstrated that the 4-arm and 6-arm SBCs have greater stability than the 3-arm SBC. Biocompatibility assessment indicated minimal cytotoxicity of the nanoaggregates, even at high concentration, making these PCL-b-PEG SBCs potentially safe and sustainable vehicles for biomedical release applications.
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Sep 2024
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[33098]
Open Access
Abstract: Nucleobases control the assembly of DNA, RNA, etc. due to hydrogen bond complementarity. By combining these unique molecules with state-of-the-art synthetic polymers, it is possible to form nanoparticles whose self-assembly behavior could be altered under orthogonal stimuli (pH and temperature). Herein, we report the synthesis of cytosine-containing nanoparticles via aqueous reversible addition-fragmentation chain transfer polymerization-induced self-assembly. A poly(N-acryloylmorpholine) macromolecular chain transfer agent (mCTA) was chain-extended with cytosine acrylamide, and a morphological phase diagram was constructed. By exploiting the ability of cytosine to form dimers via hydrogen bonding, the self-assembly behavior of cytosine-containing polymers was altered when performed under acidic conditions. Under these conditions, stable nanoparticles could be formed at longer polymer chain lengths. Furthermore, the resulting nanoparticles displayed different morphologies compared to those at pH 7. Additionally, particle stability post-assembly could be controlled by varying pH and temperature. Finally, small-angle X-ray scattering was performed to probe their dynamic behavior under thermal cycling.
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Jul 2024
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[33098]
Open Access
Abstract: Poly(proline) II helical motifs located at the protein–water interface stabilize the three-dimensional structures of natural proteins. Reported here is the first example of synthetic biomimetic poly(proline)-stabilized polypeptide nanostructures obtained by a straightforward ring-opening polymerization-induced self-assembly (ROPISA) process through consecutive N-carboxyanhydride (NCA) polymerization. It was found that the use of multifunctional 8-arm initiators is critical for the formation of nanoparticles. Worm-like micelles as well as spherical morphologies were obtained as confirmed by dynamic light scattering (DLS), transmission electron microscopy (TEM), and small angle X-ray scattering (SAXS). The loading of the nanostructures with dyes is demonstrated. This fast and open-vessel procedure gives access to amino acids-based nanomaterials with potential for applications in nanomedicine.
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Jul 2024
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[34048]
Open Access
Abstract: We report for the first time a reversible addition–fragmentation chain transfer polymerisation-induced self-assembly (RAFT-PISA) formulation in ionic liquid (IL) that yields worm gels. A series of poly(2-hydroxyethyl methacrylate)-b-poly(benzyl methacrylate) (PHEMA-b-PBzMA) block copolymer nanoparticles were synthesised via RAFT dispersion polymerisation of benzyl methacrylate in the hydrophilic IL 1-ethyl-3-methyl imidazolium dicyanamide, [EMIM][DCA]. This RAFT-PISA formulation can be controlled to afford spherical, worm-like and vesicular nano-objects, with free-standing gels being obtained over a broad range of PBzMA core-forming degrees of polymerisation (DPs). High monomer conversions (≥96%) were obtained within 2 hours for all PISA syntheses as determined by 1H NMR spectroscopy, and good control over molar mass was confirmed by gel permeation chromatography (GPC). Nanoparticle morphologies were identified using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and further detailed characterisation was conducted to monitor rheological, electrochemical and thermal characteristics of the nanoparticle dispersions to assess their potential in future electronic applications. Most importantly, this new PISA formulation in IL facilitates the in situ formation of worm ionogel electrolyte materials at copolymer concentrations >4% w/w via efficient and convenient synthesis routes without the need for organic co-solvents or post-polymerisation processing/purification. Moreover, we demonstrate that the worm ionogels developed in this work exhibit comparable electrochemical properties and thermal stability to that of the IL alone, showcasing their potential as gel electrolytes.
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Feb 2024
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