TKPlate 1.0: An Open-access platform for toxicokinetic and toxicodynamic modelling of chemicals to implement new approach methodologies in chemical risk assessment

This publication is linked to the following EFSA Supporting Publications articles: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2023.EN-8441/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2023.EN-8440/full, http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2023.EN-8437/full.

Lower oxygen saturation targets in preterm infants are not associated with increased rates of pulmonary hypertension

BACKGROUND

The optimal oxygen saturation target in preterm infants is not known. In this study, we aimed to assess the effect of lower oxygen saturation targets on the rate of bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), and pulmonary hypertension (PH) in preterm infants.

METHODS

Retrospective cohort study comparing BPD, ROP, and PH incidence among two cohorts of infants born at≤32 weeks gestation with different oxygen saturation targets at≥34 weeks post-menstrual age (PMA): cohort 1, 94-98% (n = 126); cohort 2, 92-97% (n = 121). Groups compared by Chi-square test, t-test, and multivariable logistic regression.

RESULTS

When comparing cohort 1 (average gestational age 29.8 weeks, average birth weight 1271g) with cohort 2 (average gestational age 29.6 weeks, average birth weight 1299g), there was no difference in rate of BPD (24% vs. 19%, p = 0.38), ROP (4% vs. 3%, p = 0.49), or PH (2% vs. 4%, p = 0.44).

CONCLUSION

An oxygen saturation target of 92-97% at≥34 weeks PMA was not associated with a higher rate of PH or lower rate of BPD or ROP when compared with a higher target of 94-98%.

Independent co-delivery of model actives with different degrees of hydrophilicity from oil-in-water and water-in-oil emulsions stabilised by solid lipid particles via a Pickering mechanism: a-proof-of-principle study

HYPOTHESIS

The development of vehicles for the co-encapsulation of actives with diverse characteristics and their subsequent controllable co-delivery is gaining increasing research interest. Predominantly centred around pharmaceutical applications, the majority of such co-delivery approaches have been focusing on solid formulations and less so on liquid-based systems. Simple emulsions can be designed to offer a liquid-based microstructural platform for the compartmentalised multi-delivery of actives.

EXPERIMENTS

In this work, solid lipid nanoparticle stabilised Pickering emulsions were used for the co-encapsulation/co-delivery of two model actives with different degrees of hydrophilicity. Lipid particles containing a model hydrophobic active were prepared in the presence of either Tween 20 or whey protein isolate, and were then used to stabilise water-in-oil or oil-in-water emulsions, containing a secondary model active within their dispersed phase.

FINDINGS

Solid lipid nanoparticles prepared with either type of emulsifier were able to provide stable emulsions. Release kinetic data fitting revealed that different co-delivery profiles can be achieved by controlling the surface properties of the lipid nanoparticles. The current proof-of-principle study presents preliminary data that confirm the potential of this approach to be utilised as a flexible liquid-based platform for the segregated co-encapsulation and independent co-release of different combinations of actives, either hydrophobic/hydrophilic or hydrophobic/hydrophobic, with diverse release profiles.

A flow velocity dependence of dynamic surface tension in Plateau borders of foam

HYPOTHESIS

Liquid drainage through foams is a multiscale process, that primarily occurs through channels known as Plateau borders (PBs). Recent experimental studies of isolated PBs have observed variations in channel surface tension, γ, with liquid flow rate, Q, for systems containing soluble low molecular weight surfactant (LMWS). The current study proposes that the dynamic surface tension (DST) could be responsible for this effect, where the residence time of surfactant molecules in the PB is similar to the time required for their adsorption to the channel interface.

EXPERIMENTS

Profile geometries of isolated 'ideal' PB's were created in a bespoke experimental setup at controlled forced liquid flow rates. Average surfactant residence times, τ_Res, were calculated for solutions of Sodium dodecylsulfate (SDS), Tween 20 (T20) and Tween 80 (T80), and used to calculate corresponding average DST values in discrete regions of measured PB profiles. DST values were combined with microscale drainage theory to assess the potential physical implications on liquid flow.

FINDINGS

Significant variations in the magnitude of γ were calculated based on surfactant characteristics, where only the rapid adsorption of SDS was sufficient to produce DST values approaching equilibrium. These findings seriously question assumptions of near equilibrium surface tension in LMWS foam systems above their critical micelle concentration (CMC). Furthermore, the presence of surface tension gradients identified using this discrete approach, highlights the need to further refine the current theory to a continuous approach incorporating Marangoni effects.

Impact of Pickering Intervention on the Stability of W1/O/W2 Double Emulsions of Relevance to Foods

Although water-in-oil-in-water (W₁/O/W₂) double emulsions have been associated with a spectrum of potential applications in foods, their complex microstructure is significantly unstable. Pickering stabilization, reputed for superior and longer-term interfacial stabilization when compared to surfactant-stabilized systems, could provide the opportunity to enhance double-emulsion stability. The current work presents a systematic study on the impact of progressively adopting such a Pickering intervention onto one or both interfaces of W₁/O/W₂ emulsions relevant to foods. A range of surfactants/emulsifiers and particles have been used at the W₁/O or O/W₂ interface of the W₁/O/W₂ microstructure and, where appropriate, cross-compared with the equivalent interfaces of simple emulsions (W/O and O/W, respectively). As the aqueous compartments of all investigated systems were not osmotically balanced (at the point of formulating/forming these), any advantages in terms of double-emulsion stability enhancement can be directly attributed to the employed particle stabilization. It is demonstrated that, although partial Pickering intervention can encourage stability (particularly if that is introduced at the inner W₁/O interface), only complete Pickering stabilization of the double microstructure can ensure that the oil globule size is maintained and the internal water phase is retained over a storage period of one month.

Food Structure Development in Emulsion Systems

A number of food products exist, in part or entirely, as emulsions, while others are present in an emulsified state at some point during their production/formation. Mayonnaise, butter, margarine, salad dressing, whipped cream, and ice cream represent some of the typical examples of emulsion-based foods. Controlled by both formulation and processing aspects, the emulsion architecture that is formed ultimately determines many of the attributes of the final food product. This chapter initially provides an overview of the basic constituents of emulsions and their influence on the microstructure and stability of conventional as well as more complex systems. The available spectrum of processing routes and characterization techniques currently utilized (or emerging) within the area of emulsions is then discussed. The chapter concludes with a concise outline of the relationship between food emulsion microstructure design and its performance (textural, rheological, sensorial, etc.).

Production of Oil-in-Water Emulsions with Varying Dispersed-Phase Content using Confined Impinging Jet Mixers

This work reports for the first time on the use of Confined Impinging Jet Mixers (CIJM) for the production of emulsions with dispersed-phase content up to 80 wt %, in both the surfactant-poor and -rich regimes, following the exposure to varying CIJM hydrodynamic conditions. It was observed computationally and experimentally that the CIJM capacity resulted strictly dependent on the mass jet flow rate (W _jet > 176 g/min) and the pre-emulsion droplet size (>10 μm). CIJM emulsification performance remained (almost) unaffected by the variation in the oil mass fraction. All systems showed the lowest droplet size (∼8 μm) and similar droplet size distributions under the highest W _jet. Conditionally onto the Tween20 availability, the emulsion d _3,2 was primarily determined by formulation characteristics in the surfactant poor-regime and by the CIJM energy dissipation rate in the surfactant-rich regime. In conclusion, this study offers further insights into the CIJM suitability as a realistic alternative to already-established emulsification methods.

Measuring the impact of channel length on liquid flow through an ideal Plateau border and node system

The phenomenon of foam drainage is a complex multi-scale process that unites molecular level interactions with bulk foam characteristics. Foam drainage is primarily governed by the flow of liquid in the channels and junctions that form between bubbles, which are known as Plateau borders (PBs) and nodes respectively. Existing theoretical work predicts the surface rheology of the PB and node air-liquid interface to influence liquid flow rates; however, direct experimental observations of this phenomenon remain scarce. This study recognises the clear need for a reproducible, accurate and standardised approach to directly studying liquid flow at the scale of a theoretically 'ideal' PB-node architecture. Measurements of PB geometric profiles and their apparent surface shear viscosities, μs, were made for an aqueous solution of Sodium Dodecyl Sulphate (SDS) at varying PB lengths, l1, and liquid flow rates in the range 10 μl min-1 ≤ Q ≤ 200 μl min-1. Geometric profiles displayed previously unobserved transitions between PB relaxation and expansion towards the node, with expansion dominating under conditions approaching conventional foam drainage. Average values of μs in the PB relaxation regions showed virtually inviscid behaviour, with magnitudes of 10-8 g s-1 < μs < 10-4 g s-1 for l1 in the range 27.5 mm ⪆ l1 ⪆ 8.0 mm. Decreasing magnitudes of μs and degrees of shear thinning were observed with increasing l1. This was attributed to a compressibility of the interface that was limited by an SDS concentration dependence on l1. Numerical evaluation predicted the appearance of Marangoni forces that scaled strongly with liquid shear rates, and could therefore have been responsible for the apparent shear thinning behaviour.

The role of surface active species in the fabrication and functionality of edible solid lipid particles

Lipid particles are very promising candidates for utilisation as Pickering stabilisers, and fabrication of these species has been attracting considerable academic and industrial research. Nonetheless, current understanding of these systems is hindered by the fact that, as a whole, studies reporting on the fabrication and Pickering utilisation of lipid particles vary significantly in processing conditions being utilised and formulation parameters considered. The present study investigates, under well-controlled processing and formulation conditions, the fabrication of edible lipid particles from two lipid sources in the presence of two different types of amphiphilic species (surfactant or protein) via melt-emulsification and subsequent crystallisation. Fabricated solid lipid particles were assessed in terms of their particle size, interfacial and thermal behaviour, as well as stability, as these microstructure attributes have established links to Pickering functionality. Lipid particle size and stability were controlled by the type and concentration of the used amphiphilic species (affecting the melt emulsification step) and the type of lipid source (influencing the crystallisation step). Interfacial behaviour was closely linked to the type and concentration of the surface active component used. Finally, the types of lipid and amphiphilic agents employed were found to affect lipid particle thermal behaviour the most.

Fabrication, characterisation and stability of oil-in-water emulsions stabilised by solid lipid particles: the role of particle characteristics and emulsion microstructure upon Pickering functionality

Emulsifier-mediated wettability of solid lipid particles promotes the Pickering functionality in oil-in-water emulsions.

Functional food microstructures for macronutrient release and delivery

There is a need to understand the role of fat, protein and carbohydrate in human health, and also how foods containing and/or structured using these macronutrients can be designed so that they can have a positive impact on health. This may include a reduction in fat, salt or sugar, the protection and targeted release of micronutrients or active ingredients from/to particular parts of the digestive system, improvement of gastrointestinal health or satiety enhancing properties. Such foods can be designed with various macro- and microstructures that will impact on macronutrient release and delivery. These include simple and double emulsions, the use of Pickering particles and shells, nanoparticles, liposomes, gelled networks, fluid gels and gel particles, foams, self-assembled structures, and encapsulated systems. In order to design foods that deliver these benefits understanding of how these structures behave in the gastrointestinal tract is also required, which should involve utilising both in vitro and in vivo studies. This review aims to draw together research in these areas, by focusing on the current state of the art, but also exciting possibilities for future research and food development.

Food-grade Pickering emulsions stabilised with solid lipid particles

Aqueous dispersions of tripalmitin particles (with a minimum size of 130 nm) were produced, via a hot sonication method, with and without the addition of food-grade emulsifiers.

Advances in membrane emulsification. Part B: recent developments in modelling and scale-up approaches

Membrane emulsification is a promising process for formulating emulsions and particulates. It offers many advantages over conventional 'high-shear' processes with narrower size distribution products, higher batch repeatability and lower energy consumption commonly demonstrated at a small scale. Since the process was first introduced around 25 years ago, understanding of the underlying mechanisms involved during microstructure formation has advanced significantly leading to the development of modelling approaches that predict processing output; e.g. emulsion droplet size and throughput. The accuracy and ease of application of these models is important to allow for the development of design equations which can potentially facilitate scale-up of the process and meet the manufacturer's specific requirements. Part B of this review considers the advantages and disadvantages of a variety of models developed to predict droplet size, flow behaviour and other phenomena (namely droplet-droplet interactions), with presentation of the appropriate formulae where necessary. Furthermore, the advancement of the process towards an industrial scale is also highlighted with additional recommendations by the authors for future work.

Advances in membrane emulsification. Part A: recent developments in processing aspects and microstructural design approaches

Modern emulsion processing technology is strongly influenced by the market demands for products that are microstructure-driven and possess precisely controlled properties. Novel cost-effective processing techniques, such as membrane emulsification, have been explored and customised in the search for better control over the microstructure, and subsequently the quality of the final product. Part A of this review reports on the state of the art in membrane emulsification techniques, focusing on novel membrane materials and proof of concept experimental set-ups. Engineering advantages and limitations of a range of membrane techniques are critically discussed and linked to a variety of simple and complex structures (e.g. foams, particulates, liposomes etc.) produced specifically using those techniques.

Designing food structures for nutrition and health benefits

In addition to providing specific sensory properties (e.g., flavor or textures), there is a need to produce foods that also provide functionality within the gastrointestinal (GI) tract, over and above simple nutrition. As such, there is a need to understand the physical and chemical processes occurring in the mouth, stomach, small intestine, and large intestine, in addition to the food structure-physiology interactions. In vivo techniques and in vitro models have allowed us to study and simulate these processes, which aids us in the design of food microstructures that can provide functionality within the human body. Furthermore, it is important to be aware of the health or nutritional needs of different groups of consumers when designing food structures, to provide targeted functionality. Examples of three groups of consumers (elderly, obese, and athletes) are given to demonstrate their differing nutritional requirements and the formulation engineering approaches that can be utilized to improve the health of these individuals. Eating is a pleasurable process, but foods of the future will be required to provide much more in terms of functionality for health and nutrition.

O/W emulsions stabilised by both low molecular weight surfactants and colloidal particles: The effect of surfactant type and concentration

The stability against coalescence of O/W emulsions in the presence of both surfactants and colloidal particles was investigated. In particular the effect of the surfactant type and concentration in these emulsifier mixtures on the O/W emulsions' stability was studied. Two types of surfactants were selected; those that have the ability to stabilise O/W emulsions on their own (O/W surfactants) and those that cannot (W/O surfactants). Tween 60 and Sodium Caseinate were selected as the O/W surfactants and lecithin as the W/O surfactant. Oil-in-water emulsions prepared with both particles and any of the three surfactants were stable against coalescence but, depending on the type of surfactant, the behaviour of the systems was found to depend on surfactant concentration. The droplet sizes of emulsions stabilised by mixed emulsifier systems containing low concentrations of O/W surfactants (Tween 60 or Sodium Caseinate) were smaller than those solely stabilised by either the surfactant or particles alone. At intermediate O/W surfactants concentrations, the droplet sizes of the emulsions increased. Further increases in the O/W surfactants' concentration, resulted in the complete removal of particles from the interface with the system now behaving as a surfactant-only stabilised emulsion. The behaviour of emulsions stabilised by emulsifier mixtures containing W/O surfactants was not dependent on the concentration of surfactant: no removal of particles was observed.