Situ Small-angle X-ray Scattering Research Articles

Effect of Acetaminophen on Poloxamer 407 Micelles and Hydrogels: The Relationship between Structural and Physical Properties.

Poloxamer hydrogel possesses thermosensitive sol-gel transition characteristics and is widely used as a drug-controlled-release carrier for topical or injectable formulations. In this study, the effect of loading of a drug, acetaminophen (ACE), on the physical and structural properties of poloxamer 407 (P407) micelles and hydrogels was investigated. Differential scanning calorimetry measurements revealed that ACE reduced the critical micelle temperature and enthalpy of micellization of P407 solutions. The P407 micellization was promoted by ACE incorporation. Rheometry showed that ACE increased the sol-gel transition temperature and reduced the gel strength of P407. In situ small-angle X-ray scattering (SAXS) using synchrotron radiation revealed that ACE altered the structure of P407 micelles and their packing in the P407 gels. As ACE concentration increased, the P407 micelle packing changed from a face-centered cubic phase to a body-centered cubic phase. Furthermore, ACE disordered the micelle packing structure and induced the formation of an amorphous phase. Structural analysis of the P407 micelle packing indicated that ACE reduced the aggregation number (Nagg) of P407 micelles in the gels. The SAXS study for diluted P407 solutions revealed that ACE reduced the P407 micelle size and its uniformity. The structural changes in P407 micelles by ACE loading (e.g., the reduction of Nagg, size, and size uniformity) would alter the micelle packing structure. It was found that these structural changes of micelle packing, especially the formation of an amorphous phase, could destabilize the P407 gel. As a result, the physical properties of P407 gels, such as gelation temperature and gel strength, were changed. This relationship between the structure and physical property of drug-loaded P407 gels was well-explained by correlating the micelle and gel structures. The mechanistic understanding of the change in the physical properties of P407 gels by drug loading is essential for the effective development of poloxamer gel formulations.

The Roles of Oil-Water Interfaces in Forming Ultrasmall CaSO4 Nanoparticles.

In natural and engineered environmental systems, calcium sulfate (CaSO4) nucleation commonly occurs at dynamic liquid-liquid interfaces. Although CaSO4 is one of the most common minerals in oil spills and oil-water separation, the mechanisms driving its nucleation at these liquid-liquid interfaces remain poorly understood. In this study, using in situ small-angle X-ray scattering (SAXS), we examined CaSO4 nucleation at oil-water interfaces and found that within 60 minutes of reaction, short rod-shaped nanoparticles (with a radius of gyration (Rg) of 17.2 ± 2.7 nm and a length of 38.2 ± 5.8 nm) had formed preferentially at the interfaces. Wide-angle X-ray scattering (WAXS) analysis identified these nanoparticles as gypsum (CaSO4·2H2O). In addition, spherial nanoparticles measuring 4.1 nm in diameter were observed at oil-water interfaces, where surface-enhanced Raman spectroscopy (SERS) revealed an elevated pH compared to the bulk solution. The negatively charged oil-water interfaces preferentially adsorb calcium ions, collectively promoting CaSO4 formation there. CaSO4 particle formation at the oil-water interface follows a nonclassical nucleation (N-CNT) pathway by forming ultrasmall amorphous spherical particles which then aggregate to form intermediate nanoparticles, subsequently growing into nanorod-shaped gypsum. These findings of this study provide insights into mineral scaling during membrane separation and can inform more efficient oil transport in energy recovery systems.

Numerical modeling and in situ small angle X-ray scattering characterization of ultra-small SPION magnetophoresis in a high field and gradient separator.

Magnetic nanoparticles (MNPs) have recently gained significant attention in various fields, including chemical and biomedical applications, due to their exceptional properties. However, separating MNPs from solution via magnetophoresis is challenging when MNPs are smaller than 50 nm as Brownian forces become on the order of the magnetic forces. In this study, we successfully separated small MNPs (5-30 nm) by utilizing high magnetic fields and gradients generated by economical permanent magnets. In situ small angle X-ray scattering (SAXS) was used to investigate the time-dependent concentration changes in the ferrofluid, and the results validated that only the 30 nm particles experienced particle aggregation or agglomeration, indicating that dipole-dipole interactions did not play a discernable role in the separation process for particles smaller than ∼15 nm. However, numerical simulations have provided further validation that in the absence of particle-particle interactions, even MNPs with diameters less than 15 nm exhibited magnetophoresis that effectively counteracted the effects of Brownian motion.

In situ SAXS investigation of vinyl acetate polymerization-induced self-assembly

In situ small angle X-ray scattering (SAXS) was used to investigate the formation of higher-order morphologies in vinyl acetate (VAc) polymerization-induced self-assembly (PISA).

Precipitation kinetics of precipitates with different orientations and segregation in an ultrafine grained Al–Cu–Mg alloy

The precipitation kinetics of precipitates with different orientations and segregation in an ultrafine grained (UFG) Al–Cu–Mg alloy (AA2024) aged at 210 °C have been investigated using situ small angle X-ray scattering (SAXS), situ wide angle X-ray (WAXS) and Transmission Electron Microscopy (TEM). For UFG alloy, the number and size of (111) S'/S phases are larger than those of (130) S'/S phases on the whole, because spacing of slip plane near (111) S'/S phases is larger than that near (130) S'/S phases, resulting in solute atoms are easier to diffusion near (111) S'/S phases, and (111) S'/S phases are easier to grow, meanwhile, resulting in the critical shear stress for dislocation moving near (111) S'/S phases is smaller than that near (130) S'/S phases, further leading to the dislocation density near (111) S'/S phases is 1.07–1.19 times larger compared to that near (130) S'/S phases during ageing process, which provides more nucleation sites for (111) S'/S phases. After ageing for 10–40 min, the segregation degree of Cu and Mg atoms near dislocations and grain boundaries is increased in UFG alloy, while after ageing for 80 min, the segregation of Cu atoms is decreased and Mg atoms continue to increase, the segregation of Mg atoms begin to decrease after ageing for 120 min.

Revealing Deformation Mechanisms in Polymer-Grafted Thermoplastic Elastomers via In Situ Small-Angle X-ray Scattering.

The tunable properties of thermoplastic elastomers (TPEs), through polymer chemistry manipulations, enable these technologically critical materials to be employed in a broad range of applications. The need to "dial-in" the mechanical properties and responses of TPEs generally requires the design and synthesis of new macromolecules. In these designs, TPEs with nonlinear macromolecular architectures outperform the mechanical properties of their linear copolymer counterparts, but the differences in the deformation mechanism providing enhanced performance are unknown. Here, in situ small-angle X-ray scattering (SAXS) measurements during uniaxial extension reveal distinct deformation mechanisms between a commercially available linear poly(styrene)-poly(butadiene)-poly(styrene) (SBS) triblock copolymer and the grafted SBS version containing grafted poly(styrene) (PS) chains from the poly(butadiene) (PBD) midblock. The neat SBS (φSBS = 100%) sample deforms congruently with the macroscopic dimensions, with the domain spacing between spheres increasing and decreasing along and transverse to the stretch direction, respectively. At high extensions, end segment pullout from the PS-rich domains is detected, which is indicated by a disordering of SBS. Conversely, the PS-grafted SBS that is 30 vol % SBS and 70% styrene (φSBS = 30%) exhibits a lamellar morphology, and in situ SAXS measurements reveal an unexpected deformation mechanism. During deformation, there are two simultaneous processes: significant lamellar domain rearrangement to preferentially orient the lamellae planes parallel to the stretch direction and crazing. The samples whiten at high strains as expected for crazing, which corresponds with the emergence of features in the 2D SAXS pattern during stretching consistent with fibril-like structures that bridge the voids in crazes. The significant domain rearrangement in the grafted copolymers is attributed to the new junctions formed across multiple PS domains by the grafting of a single chain. The in situ SAXS measurements provide insights into the enhanced mechanical properties of grafted copolymers that arise through improved physical cross-linking that leads to nanostructure domain reorientation for self-reinforcement and craze formation where fibrils help to strengthen the polymer.

Continuous-Flow Laboratory SAXS for In Situ Determination of the Impact of Hydrophilic Block Length on Spherical Nano-Object Formation during Polymerization-Induced Self-Assembly.

In situ small-angle X-ray scattering (SAXS) is a powerful technique for characterizing block-copolymer nano-object formation during polymerization-induced self-assembly. To work effectively in situ, it requires high intensity X-rays which enable the short acquisition times required for real-time measurements. However, routine access to synchrotron X-ray sources is expensive and highly competitive. Flow reactors provide an opportunity to obtain temporal resolution by operating at a consistent flow rate. Here, we equip a flow-reactor with an X-ray transparent flow-cell at the outlet which facilitates the use of a low-flux laboratory SAXS instrument for in situ monitoring. The formation and morphological evolution of spherical block copolymer nano-objects was characterized during reversible addition fragmentation chain transfer polymerization of diacetone acrylamide in the presence of a series of poly(dimethylacrylamide) (PDMAm) macromolecular chain transfer agents with varying degrees of polymerization. SAXS analysis indicated that during the polymerization, highly solvated, loosely defined aggregates form after approximately 100 s, followed by expulsion of solvent to form well-defined spherical particles with PDAAm cores and PDMAm stabilizer chains, which then grow as the polymerization proceeds. Analysis also indicates that the aggregation number (Nagg) increases during the reaction, likely due to collisions between swollen, growing nanoparticles. In situ SAXS conducted on PISA syntheses using different PDMAm DPs indicated a varying conformation of the chains in the particle cores, from collapsed chains for PDMAm47 to extended chains for PDMAm143. At high conversion, the final Nagg decreased as a function of increasing PDMAm DP, indicating increased steric stabilization afforded by the longer chains which is reflected by a decrease in both core diameter (from SAXS) and hydrodynamic diameter (from DLS) for a constant core DP of 400.

In Situ Monitoring of Drug Precipitation from Digesting Lipid Formulations Using Low-Frequency Raman Scattering Spectroscopy.

Low-frequency Raman spectroscopy (LFRS) is a valuable tool to detect the solid state of amorphous and crystalline drugs in solid dosage forms and the transformation of drugs between different polymorphic forms. It has also been applied to track the solubilisation of solid drugs as suspensions in milk and infant formula during in vitro digestion. This study reports the use of LFRS as an approach to probe drug precipitation from a lipid-based drug delivery system (medium-chain self-nanoemulsifying drug delivery system, MC-SNEDDS) during in vitro digestion. Upon lipolysis of the digestible components in MC-SNEDDS containing fenofibrate as a model drug, sharp phonon peaks appeared at the low-frequency Raman spectral region (<200 cm-1), indicating the precipitation of fenofibrate in a crystalline form from the formulation. Two multivariate data analysis approaches (principal component analysis and partial least squares discriminant analysis) and one univariate analysis approach (band ratios) were explored to track these spectral changes over time. The low-frequency Raman data produces results in good agreement with in situ small angle X-ray scattering (SAXS) measurements with all data analysis approaches used, whereas the mid-frequency Raman requires the use of PLS-DA to gain similar results. This suggests that LFRS can be used as a complementary, and potentially more accessible, technique to SAXS to determine the kinetics of drug precipitation from lipid-based formulations.

Hybridizing a Dual-Cross Network and a Linear Glassy Polymer for Dynamic Contributions to High Mechanical Toughness Based on Phase-Separated Structures

Bulk copolymerization of alkyl acrylate and cyclodextrin (CD) host monomers forms a single movable cross network (SC), in which the CD units act as movable cross-linkers. Moreover, the bulk copolymerization of the CD monomer and main chain monomer in the presence of SC results in dual-cross-network (DC) elastomers. DC elastomers result in good toughness (Gf). Here, to improve Gf and Young’s modulus (E), we hybridized DC elastomers with tertiary glassy polymers, which are called DCP elastomers. We prepared the DCP elastomers by photopolymerization of N,N-dimethylacrylamide (DMAA) and poly(2-methoxyethyl acrylate) (MEA) in the presence of DC. A DCP elastomer with a suitable weight percent (wt %) of the glassy polymer shows high Gf (108.4 MJ m–3) and E (223.4 MPa) values. Dynamic mechanical analysis (DMA) and in situ small-angle X-ray scattering (SAXS) measurements under uniaxial stretching indicate multiple deformations based on phase-separated structures. We suggest that the phase-separated structures of DCP elastomers cause a large stress dissipation, which contributes to high toughness.

Optimizing surfactant removal from a soft-templated ordered mesoporous carbon precursor: an in situ SAXS study.

In situ small-angle X-ray scattering (SAXS) was employed to identify critical parameters during thermal treatment for template removal of an ordered mesoporous carbon precursor synthesized via a direct soft-templating route. The structural parameters obtained from the SAXS data as a function of time were the lattice parameter of the 2D hexagonal structure, the diameter of the cylindrical mesostructures and a power-law exponent characterizing the interface roughness. Moreover, detailed information on contrast changes and pore lattice order was obtained from analysis of the integrated SAXS intensity of the Bragg and diffuse scattering separately. Five characteristic regions during heat treatment were identified and discussed regarding the underlying dominant processes. The influence of temperature and O2/N2 ratio on the final structure was analyzed, and parameter ranges were identified for an optimized template removal without strongly affecting the matrix. The results indicate that the final structure and controllability of the process are optimum for temperatures between 260 and 300°C with a gas flow containing 2 mol% of O2.

Electrical Conductivity and In Situ SAXS Probing of Block Copolymer Nanocomposites Under Mechanical Stretching.

Elastomers based on block copolymers can self-organize into ordered nanoscale structures, making them attractive for use as flexible conductive nanocomposites. Understanding how ordered structures impact electrical properties is essential for practical applications. This study investigated the morphological evolution of flexible conductive elastomers based on polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers with aligned single- or multi-wall carbon nanotubes (SWCNTs or MWCNTs) and their electrical conductivity under large deformations. Oriented nanocomposites were obtained through injection molding and characterized using two different setups: tensile testing monitored by in situ small-angle X-ray scattering (SAXS) and tensile testing with simultaneous electrical conductivity measurements. Our findings demonstrate that structural orientation significantly influences electrical conductivity, with higher conductivity in the longitudinal direction due to the preferred orientation of carbon nanotubes. Tensile testing demonstrated that carbon nanotubes accelerate the process of realignment of the ordered structure. As a consequence, higher deformations reduced the conductivity of samples with longitudinal alignment due to the disruption of percolation contacts between nanotubes, while in samples with a transverse alignment the process promoted the formation of a new conductive network, increasing electrical conductivity.

Calcium Carbonate Prenucleation Cluster Pathway Observed via In Situ Small-Angle X-ray Scattering.

For more than 150 years, our understanding of solid-phase mineral formation from dissolved constituent ions in aqueous environments has been dominated by classical nucleation theory (CNT). However, an alternative paradigm known as non-classical nucleation theory (NCNT), characterized by the existence of thermodynamically stable and highly hydrated ionic "prenucleation clusters" (PNCs), is increasingly invoked to explain mineral nucleation, including the formation of calcium carbonate (CaCO3) minerals in aqueous conditions, which is important in a wide range of geological and biological systems. While the existence and role of PNCs in aqueous nucleation processes remain hotly debated, we show, using in situ small-angle X-ray scattering (SAXS), that nanometer-sized clusters are present in aqueous CaCO3 solutions ranging from thermodynamically under- to supersaturated conditions regarding all known mineral phases, thus demonstrating that CaCO3 mineral formation cannot be explained solely by CNT under the conditions examined.

Effects of microstructure on the retention of proton conductivity of Nafion/SiO2 composite membranes at elevated temperatures:An in situ SAXS study

The operating temperature of modified Nafion membranes remains too low to satisfy the requirements for high-temperature proton exchange membrane fuel cells (HT-PEMFCs) because most can only operate well below 120 °C. In this article, we prepare a series of Nafion/SiO2 composite membranes with different contents of doped silica nanoparticles by in situ growth of SiO2 nanoparticles near the –SO3H group. The water dynamic change process and the functional properties of Nafion/SiO2 composite membranes are studied and found to correlate well with structural parameters, such as crystallinity and average chain spacing. Also, microstructure information including the phase separation structure changes, structural complexity, and ion cluster fraction of Nafion/SiO2 composite membranes at different temperatures are investigated using synchrotron-based in situ small angle X-ray scattering (SAXS). Differing from expectations, the amount of water in the Nafion/SiO2 composite membranes may not be the decisive factor to maintain proton conductivity at relatively high temperatures. Instead, the complexity or connectivity of the proton transport channel may play a more important role in the effective proton transfer inside the composite membranes, which also provides valuable guidance and insight for the development of novel HT-PEM materials with well-designed ion transport pathways in the future.

The structural changes of a bovine casein micelle during temperature change; in situ observation over a wide spatial scale from nano to micrometer.

Bovine milk is the complex colloidal system containing nano to micrometer scale components. Earlier, our research group reported the structural changes in bovine casein micelles in the temperature range of 10-40 °C by in situ small-angle X-ray scattering (SAXS) [H. Takagi, T. Nakano, T. Aoki and M. Tanimoto, Food Chem., 2022, 393, 133389]. In this study, we extend our previous research by investigating the temperature-associated structural alterations in casein micelles over a wide spatial scale using in situ SAXS and ultra-SAXS (USAXS). Furthermore, the temperature dependences of various physical properties of the casein micelles were investigated by analyzing the SAXS intensities. The USAXS results showed that micelles formed 1-dimensional aggregates and that these aggregate structures did not change in the temperature range of 10-40 °C. Changes in electron densities calculated from SAXS intensities showed that the voluminosity reduced and the weight fraction of protein inside the micelles increased during the heating process. The number of water domains in a micelle decreased when the temperature increased from 10 to 40 °C, but did not substantially change in the cooling run at a rate of 1 °C min-1. The number of colloidal calcium phosphate (NCCP) in a micelle can also be calculated from the SAXS intensities; NCCP increases upon heating. This study on the behavior of casein micelles with respect to temperature change in milk over a wide spatial scale showed that the casein micelle structure was sensitive to temperature and can change dramatically with temperature variations.

Revisiting the Dissolution of Praziquantel in Biorelevant Media and the Impact of Digestion of Milk on Drug Dissolution.

Praziquantel is a poorly water-soluble drug used to treat parasitic infections. Previous studies have suggested that its rate and extent of dissolution in milk and biorelevant media are slow and limited compared to dissolution in the pharmacopoeial-recommended medium, despite being reported as displaying a positive food effect upon administration. This study aimed to revisit the dissolution of praziquantel in biorelevant media and milk to better understand this apparent dichotomy. The context of digestion was introduced to better understand drug solubilisation under more relevant gastrointestinal conditions. The amount of praziquantel solubilised in the various media during digestion was quantified using high performance liquid chromatography (HPLC) and the kinetics of dissolution were confirmed by tracking the disappearance of solid crystalline drug using in situ small angle X-ray scattering (SAXS). For the dissolution media, where sodium lauryl sulfate (SLS) is typically included as a wetting agent, a prominent effect of SLS on drug dissolution was also apparent where >2.5 fold more drug was solubilised in SLS-containing dissolution medium compared to that without (0.1 M HCl only). In milk, significant dissolution of praziquantel was observed only during digestion and not during dispersion, hence suggesting that (1) milk can be potentially administered with praziquantel to improve oral bioavailability and (2) incorporating a digestion step into existing in vitro dissolution testing can better reflect the potential for a positive food effect when lipids are present.

Investigating the Particle Growth in Bimodal Pt/C Catalysts by In-Situ Small-Angle X-ray Scattering: Challenges in the Evaluation of Stress Test Protocol-Dependent Degradation Mechanisms

The influence of different combinations of accelerated stress test (AST) protocols simulating load-cycle and start/stop conditions of a proton exchange membrane fuel cell (PEMFC) vehicle is investigated on a bimodal Pt/C catalyst. The bimodal Pt/C catalyst, prepared by mixing two commercial catalysts, serves as a model system and consists of two distinguishable size populations. The change in mean particle size was investigated by in situ small-angle X-ray scattering (SAXS). The comparison to the reference catalysts, i.e., the two single-size population catalysts, uncovers the presence of electrochemical Ostwald ripening as a degradation mechanism in the bimodal catalyst. Increasing the harshness of the applied AST protocol combinations by faster changing between load-cycle or start/stop conditions, the particle size of the larger population of the bimodal catalyst increases faster than expected. Surprisingly, the change in mean particle size of the smaller size population indicates a smaller increase for harsher AST protocols, which might be explained by a substantial electrochemical Ostwald ripening.

In situ small-angle X-ray scattering reveals strong condensation of DNA origami during silicification

Silicification of DNA origami structures increases their stability and provides chemical protection. Yet, it is unclear whether the whole DNA framework is embedded or if silica just forms an outer shell and how silicification affects the origami’s internal structure. Employing in situ small-angle X-ray scattering (SAXS), we show that addition of silica precursors induces substantial condensation of the DNA origami at early reaction times by almost 10 %. Subsequently, the overall size of the silicified DNA origami increases again due to increasing silica deposition. We further identify the SAXS Porod invariant as a reliable, model-free parameter for the evaluation of the amount of silica formation at a given time. Contrast matching of the DNA double helix Lorentzian peak reveals silica growth also inside the origami. The less polar silica forming within the origami structure, replacing more than 40 % of the internal hydration water, causes a hydrophobic effect: condensation. DNA origami objects with flat surfaces show a strong tendency towards aggregation during silicification, presumably driven by the same entropic forces causing condensation. Maximally condensed origami displayed thermal stability up to 60 °C. Our studies provide insights into the silicification reaction allowing for the formulation of optimized reaction protocols.

Functionalized Cellulose Nanofibers as Crosslinkers to Produce Chitosan Self-Healing Hydrogel and Shape Memory Cryogel.

Cellulose nanofibers functionalized with multiple aldehyde group were synthesized as the crosslinker to produce composite self-healing hydrogel and shape memory cryogel from chitosan. The hydrogel possessed effective self-healing (∼100% efficiency) and shear-thinning properties. The cryogel had macroporous structure, large water absorption (>4300%), and high compressibility. Both hydrogel and cryogel were injectable. In particular, the cryogel (nanocellulose/chitosan 1:6) revealed thermally induced shape memory, the mechanism of which was elucidated by in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) as changes in orientation of the induced crystalline structure during the shape memory program. The shape memory cryogel with a large size (15 mm × 10 mm × 1.1 mm) injected through a 16 G syringe needle was recoverable in 37 °C water. Moreover, the cryogel was cytocompatible and promoted cell growth. The nanocellulose-chitosan composite hydrogel and cryogel are injectable and degradable biomaterials with adjustable mechanical properties for potential medical applications.

On the Optimization of Ni/A and Ni/X Synthesis Procedure toward Active and Selective Catalysts for the Production of CH4 from CO2

Herein, optimization of zeolite NaA/NaX synthesis conditions in order to obtain the final product with high surface area and pore volume was investigated. An optimal synthesis condition was 5 days aging time and crystallization time of 9 h with the co-addition of cetyltrimethylammonium bromide (CTAB) and heptane. All those optimal synthesis conditions provided mixed phase between zeolite NaA and NaX, and addition of those organic phases improved the surface area and pore volume of the final synthesized zeolite. The role of CTAB and heptane on increasing the surface area of zeolite was studied by in situ small-angle X-ray scattering (SAXS). The SAXS results evidenced that small nucleation precursor was formed upon the addition of organic phase, and this nucleation precursor can provide zeolite with high-characteristic XRD signals of mixed phase of zeolite A and X after the crystallization process. The synthesized zeolite obtained from optimal synthesis condition with high surface area was further used as a catalyst support by impregnating with 5, 10, 15, and 20wt%Ni for catalyzing CO2 methanation reaction. The results found that 15wt%Ni/zeolite expressed the highest catalytic activity with high CH4 selectivity and stability. This was due to high dispersion of Ni species on catalyst surface and high metal-support interaction between Ni and zeolite. These results indicated that the mixed phase zeolite support can be a potential catalyst support for this reaction.

Gold Nanoprobes Exploring the Ice Structure in the Aqueous Dispersion of Poly(Ethylene Glycol)-Gold Hybrid Nanoparticles.

Ice structures and their formation process are fundamentally important to cryobiology, geoscience, and physical chemistry. In this work, we synthesized gold nanoprobes by grafting water-soluble polyethylene glycol (PEG) onto spherical gold nanoparticles and analyzed the structure of ice formation in the vicinity of the resulting hybrid PEG-Au nanoparticles (AuPEGNPs). Temperature-dependent in situ small-angle X-ray scattering (SAXS) indicated that AuPEGNPs, like PEG, caused the formation of bulk spherulite ice. Unlike for PEG, we observed the formation of lamellar ice with a periodicty of 4.6 nm, which is thermodynamically less stable than the bulk form. The lamellar ice formed after AuPEGNP agglomeration during cooling at -19 °C, and it remained during subsequent heating from -20 to -11 °C and melted at around -10 °C, far below the melting temperature of bulk ice. We explain different effects of AuPEGNP and free PEG on ice formation by the topological differences. The highly concentrated PEG chains on the agglomerated Au cores lead to the formation of PEG-hydrates that assemble into lamellar ice with a periodicity of 4.6 nm.