pH-Dependent Lyotropic Liquid Crystalline Mesophase and Ionization Behavior of Phytantriol-Based Ionizable Lipid Nanoparticles.

Self-assembled lipid nanoparticles (LNPs), serving as essential nanocarriers in recent COVID-19 mRNA vaccines, provide a stable and versatile platform for delivering a wide range of biological materials. Notably, LNPs with unique inverse mesostructures, such as cubosomes and hexosomes, are recognized as fusogenic nanocarriers in the drug delivery field. This study delves into the physicochemical properties, including size, lyotropic liquid crystalline mesophase, and apparent pKa of LNPs with various lipid components, consisting of two ionizable lipids (ALC-0315 and SM-102) used in commercial COVID-19 mRNA vaccines and a well-known inverse mesophase structure-forming helper lipid, phytantriol (PT). Two partial mesophase diagrams are generated for both ALC-0315/PT LNPs and SM-102/PT LNPs as a function of two factors, ionizable lipid ratio (α, 0-100 mol%) and pH condition (pH 3-11). Furthermore, the impact of different LNP stabilizers (Pluronic F127, Pluronic F108, and Tween 80) on their pH-dependent phase behavior is evaluated. The findings offer insights into the self-assembled mesostructure and ionization state of the studied LNPs with potentially enhanced endosomal escape ability. This research is relevant to developing innovative next-generation LNP systems for delivering various therapeutics.

A Barley Efflux Transporter Operates in a Na+-Dependent Manner, as Revealed by a Multidisciplinary Platform.

Plant growth and survival depend upon the activity of membrane transporters that control the movement and distribution of solutes into, around, and out of plants. Although many plant transporters are known, their intrinsic properties make them difficult to study. In barley (Hordeum vulgare), the root anion-permeable transporter Bot1 plays a key role in tolerance to high soil boron, facilitating the efflux of borate from cells. However, its three-dimensional structure is unavailable and the molecular basis of its permeation function is unknown. Using an integrative platform of computational, biophysical, and biochemical tools as well as molecular biology, electrophysiology, and bioinformatics, we provide insight into the origin of transport function of Bot1. An atomistic model, supported by atomic force microscopy measurements, reveals that the protein folds into 13 transmembrane-spanning and five cytoplasmic α-helices. We predict a trimeric assembly of Bot1 and the presence of a Na(+) ion binding site, located in the proximity of a pore that conducts anions. Patch-clamp electrophysiology of Bot1 detects Na(+)-dependent polyvalent anion transport in a Nernstian manner with channel-like characteristics. Using alanine scanning, molecular dynamics simulations, and transport measurements, we show that conductance by Bot1 is abolished by removal of the Na(+) ion binding site. Our data enhance the understanding of the permeation functions of Bot1.

Gd-DTPA-Dopamine-Bisphytanyl Amphiphile: Synthesis, Characterisation and Relaxation Parameters of the Nanoassemblies and Their Potential as MRI Contrast Agents.

Here, a new amphiphilic magnetic resonance imaging (MRI) contrast agent, a Gd(III)-chelated diethylenetriaminepentaacetic acid conjugated to two branched alkyl chains via a dopamine spacer, Gd-DTPA-dopamine-bisphytanyl (Gd-DTPA-Dop-Phy), which is readily capable of self-assembling into liposomal nanoassemblies upon dispersion in an aqueous solution, is reported. In vitro relaxivities of the dispersions were found to be much higher than Magnevist, a commercially available contrast agent, at 0.47 T but comparable at 9.40 T. Analysis of variable temperature (17)O NMR transverse relaxation measurements revealed the water exchange of the nanoassemblies to be faster than that previously reported for paramagnetic liposomes. Molecular reorientation dynamics were probed by (1)H NMRD profiles using a classical inner and outer sphere relaxation model and a Lipari-Szabo "model-free" approach. High payloads of Gd(III) ions in the liposomal nanoassemblies made solely from the Gd-DTPA-Dop-Phy amphiphiles, in combination with slow molecular reorientation and fast water exchange makes this novel amphiphile a suitable candidate to be investigated as an advanced MRI contrast agent.

Exploiting topology-directed nanoparticle disassembly for triggered drug delivery.

The physical properties of cyclic and linear polymers are markedly different; however, there are few examples which exploit these differences in clinical applications. In this study, we demonstrate that self-assemblies comprised of cyclic-linear graft copolymers are significantly more stable than the equivalent linear-linear graft copolymer assemblies. This difference in stability can be exploited to allow for triggered disassembly by cleavage of just a single bond within the cyclic polymer backbone, via disulfide reduction, in the presence of intracellular levels of l-glutathione. This topological effect was exploited to demonstrate the first example of topology-controlled particle disassembly for the controlled release of an anti-cancer drug in vitro. This approach represents a markedly different strategy for controlled release from polymer nanoparticles and highlights for the first time that a change in polymer topology can be used as a trigger in the design of delivery vehicles. We propose such constructs, which demonstrate disassembly behavior upon a change in polymer topology, could find application in the targeted delivery of therapeutic agents.

Seal or Varnish? A randomised controlled trial to determine the relative cost and effectiveness of pit and fissure sealant and fluoride varnish in preventing dental decay.

BACKGROUND: Fissure sealant (FS) and fluoride varnish (FV) have been shown to be effective in preventing dental caries when tested against a no-treatment control. However, the relative clinical effectiveness and cost-effectiveness of these interventions is unknown. OBJECTIVE: To compare the clinical effectiveness and cost-effectiveness of FS and FV in preventing dental caries in first permanent molars (FPMs) in 6- and 7-year-olds and to determine their acceptability. DESIGN: A randomised controlled allocation-blinded clinical trial with two parallel arms. SETTING: A targeted population programme using mobile dental clinics (MDCs) in schools located in areas of high social and economic deprivation in South Wales. PARTICIPANTS: In total, 1016 children were randomised, but one parent subsequently withdrew permission and so the analysis was based on 1015 children. The randomisation of participants was stratified by school and balanced for sex and primary dentition baseline caries levels using minimisation in a 1 : 1 ratio for treatments. A random component was added to the minimisation algorithm, such that it was not completely deterministic. Of the participants, 514 were randomised to receive FS and 502 were randomised to receive FV. INTERVENTIONS: Resin-based FS was applied to caries-free FPMs and maintained at 6-monthly intervals. FV was applied at baseline and at 6-month intervals over the course of 3 years. MAIN OUTCOME MEASURES: The proportion of children developing caries into dentine (decayed, missing, filled teeth in permanent dentition, i.e. D4-6MFT) on any one of up to four treated FPMs after 36 months. The assessors were blinded to treatment allocation; however, the presence or absence of FS at assessment would obviously indicate the probable treatment received. Economic measures established the costs and budget impact of FS and FV and the relative cost-effectiveness of these technologies. Qualitative interviews determined the acceptability of the interventions. RESULTS: At 36 months, 835 (82%) children remained in the trial: 417 in the FS arm and 418 in the FV arm. The proportion of children who developed caries into dentine on a least one FPM was lower in the FV arm (73; 17.5%) than in the FS arm (82, 19.6%) [odds ratio (OR) 0.84, 95% confidence interval (CI) 0.59 to 1.21; p = 0.35] but the difference was not statistically significant. The results were similar when the numbers of newly decayed teeth (OR 0.86, 95% CI 0.60 to 1.22) and tooth surfaces (OR 0.85, 95% CI 0.59 to 1.21) were examined. Trial fidelity was high: 95% of participants received five or six of the six scheduled treatments. Between 74% and 93% of sealants (upper and lower teeth) were intact at 36 months. The costs of the two technologies showed a small but statistically significant difference; the mean cost to the NHS (including intervention costs) per child was £500 for FS, compared with £432 for FV, a difference of £68.13 (95% CI £5.63 to £130.63; p = 0.033) in favour of FV. The budget impact analysis suggests that there is a cost saving of £68.13 (95% CI £5.63 to £130.63; p = 0.033) per child treated if using FV compared with the application of FS over this time period. An acceptability score completed by the children immediately after treatment and subsequent interviews demonstrated that both interventions were acceptable to the children. No adverse effects were reported. LIMITATIONS: There are no important limitations to this study. CONCLUSIONS: In a community oral health programme utilising MDCs and targeted at children with high caries risk, the twice-yearly application of FV resulted in caries prevention that is not significantly different from that obtained by applying and maintaining FSs after 36 months. FV proved less expensive. FUTURE WORK: The clinical effectiveness and cost-effectiveness of FS and FV following the cessation of active intervention merits investigation. TRIAL REGISTRATION: EudraCT number 2010-023476-23, Current Controlled Trials ISRCTN17029222 and UKCRN reference 9273. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 21. See the NIHR Journals Library website for further project information.

Epidermal growth factor receptor-targeted lipid nanoparticles retain self-assembled nanostructures and provide high specificity.

Next generation drug delivery utilising nanoparticles incorporates active targeting to specific sites. In this work, we combined targeting with the inherent advantages of self-assembled lipid nanoparticles containing internal nano-structures. Epidermal growth factor receptor (EGFR)-targeting, PEGylated lipid nanoparticles using phytantriol and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-PEG-maleimide amphiphiles were created. The self-assembled lipid nanoparticles presented here have internal lyotropic liquid crystalline nano-structures, verified by synchrotron small angle X-ray scattering and cryo-transmission electron microscopy, that offer the potential of high drug loading and enhanced cell penetration. Anti-EGFR Fab' fragments were conjugated to the surface of nanoparticles via a maleimide-thiol reaction at a high conjugation efficiency and retained specificity following conjugation to the nanoparticles. The conjugated nanoparticles were demonstrated to have high affinity for an EGFR target in a ligand binding assay.

Construction of DNA-polymer hybrids using intercalation interactions.

Reversible addition-fragmentation chain transfer (RAFT) polymerisation was used to produce a range of polymers terminated with an acridine group, which intercalates efficiently into dsDNA; the structure of the polymer determines the nature and strength of the interaction. Using a short 63 base pair dsDNA, discrete and well-defined DNA-polymer hybrid nanoparticles were formed, which were characterised by dynamic light scattering, small-angle X-ray scattering and atomic force microscopy.

Structural reorganization of cylindrical nanoparticles triggered by polylactide stereocomplexation.

Co-crystallization of polymers with different configurations/tacticities provides access to materials with enhanced performance. The stereocomplexation of isotactic poly(L-lactide) and poly(D-lactide) has led to improved properties compared with each homochiral material. Herein, we report the preparation of stereocomplex micelles from a mixture of poly(L-lactide)-b-poly(acrylic acid) and poly(D-lactide)-b-poly(acrylic acid) diblock copolymers in water via crystallization-driven self-assembly. During the formation of these stereocomplex micelles, an unexpected morphological transition results in the formation of dense crystalline spherical micelles rather than cylinders. Furthermore, mixture of cylinders with opposite homochirality in either THF/H2O mixtures or in pure water at 65 °C leads to disassembly into stereocomplexed spherical micelles. Similarly, a transition is also observed in a related PEO-b-PLLA/PEO-b-PDLA system, demonstrating wider applicability. This new mechanism for morphological reorganization, through competitive crystallization and stereocomplexation and without the requirement for an external stimulus, allows for new opportunities in controlled release and delivery applications.

Precious metal carborane polymer nanoparticles: characterisation of micellar formulations and anticancer activity.

We report the encapsulation of highly hydrophobic 16-electron organometallic ruthenium and osmium carborane complexes [Ru/Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolate)] ( and ) in Pluronic® triblock copolymer P123 core-shell micelles. The spherical nanoparticles and , dispersed in water, were characterized by dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and synchrotron small-angle X-ray scattering (SAXS; diameter ca. 15 and 19 nm, respectively). Complexes and were highly active towards A2780 human ovarian cancer cells (IC(50) 0.17 and 2.50 µM, respectively) and the encapsulated complexes, as and nanoparticles, were less potent (IC(50) 6.69 µM and 117.5 µM, respectively), but more selective towards cancer cells compared to normal cells.