Long-term stability in perovskite solar cells through atomic layer deposition of tin oxide.

Robust contact schemes that boost stability and simplify the production process are needed for perovskite solar cells (PSCs). We codeposited perovskite and hole-selective contact while protecting the perovskite to enable deposition of SnOx/Ag without the use of a fullerene. The SnOx, prepared through atomic layer deposition, serves as a durable inorganic electron transport layer. Tailoring the oxygen vacancy defects in the SnOx layer led to power conversion efficiencies (PCEs) of >25%. Our devices exhibit superior stability over conventional p-i-n PSCs, successfully meeting several benchmark stability tests. They retained >95% PCE after 2000 hours of continuous operation at their maximum power point under simulated AM1.5 illumination at 65°C. Additionally, they boast a certified T97 lifetime exceeding 1000 hours.

Potent BODIPY-based photosensitisers for selective mitochondrial dysfunction and effective photodynamic therapy.

The development of new and improved mitochondria-targeting photosensitisers (PSs) for photodynamic therapy (PDT) remains highly desirable, due to the critical role the mitochondria play in maintaining healthy cellular function. Here, we report the design, synthesis, photophysical properties and biological characterisation of a series of di-iodinated BODIPY-based PSs, BODIPY-Mito-I-n, for mitochondria-targeted PDT applications. Six BODIPY-Mito-I-n analogues were synthesised in good yields, with fast reaction times of between 30 and 60 min under mild conditions. The di-iodination of the BODIPY scaffold enabled highly efficient population of the triplet state, leading to high singlet oxygen (1O2) photosensitisation efficiencies (ΦΔ = 0.55-0.65). All BODIPY-Mito-I-n compounds exhibited very high photocytotoxic activity towards HeLa cells, with IC50,light values of between 1.30 and 6.93 nM, due to photoinduced 1O2 generation. Notably, the poly(ethylene glycol) (PEG)-modified BODIPY-Mito-I-6 showed remarkably lower dark cytotoxicity (IC50,dark = 6.68-7.25 µM) than the non-PEGylated analogues BODIPY-Mito-I-1 to BODIPY-Mito-I-5 (IC50,dark = 0.58-1.09 µM), resulting in photocytotoxicity indices up to 2120. Mechanistic studies revealed that BODIPY-Mito-I-6 induced reactive oxygen species overproduction and mitochondrial dysfunction in cells upon irradiation, leading to significant cell death through a combination of apoptosis and necrosis. It is anticipated that our design will contribute to the development of more effective mitochondria-targeting PSs for cancer therapy.

Interface Engineering of Water-Dispersible Near-Infrared-Emitting CuInZnS/ZnSe/ZnS Quantum Dots.

We report the synthesis of near-infrared (IR)-emitting core/shell/shell quantum dots of CuInZnS/ZnSe/ZnS and their phase transfer to water. The intermediate ZnSe shell was added to inhibit the migration of ions from the standard ZnS shell into the emitting core, which often leads to a blue shift in the emission profile. By engineering the interface between the core and terminal shell layer, the optical properties can be controlled, and emission was maintained in the near-IR region, making the materials attractive for biological applications. In addition, the hydrodynamic diameter of the particle was controlled using amphiphilic polymers.

Highly Efficient and Scalable p-i-n Perovskite Solar Cells Enabled by Poly-metallocene Interfaces.

Inverted p-i-n perovskite solar cells (PSCs) are easy to process but need improved interface characteristics with reduced energy loss to prevent efficiency drops when increasing the active photovoltaic area. Here, we report a series of poly ferrocenyl molecules that can modulate the perovskite surface enabling the construction of small- and large-area PSCs. We found that the perovskite-ferrocenyl interaction forms a hybrid complex with enhanced surface coordination strength and activated electronic states, leading to lower interfacial nonradiative recombination and charge transport resistance losses. The resulting PSCs achieve an enhanced efficiency of up to 26.08% for small-area devices and 24.51% for large-area devices (1.0208 cm2). Moreover, the large-area PSCs maintain >92% of the initial efficiency after 2000 h of continuous operation at the maximum power point under 1-sun illumination and 65 °C.

Mitochondria-targeting biocompatible fluorescent BODIPY probes.

An increase in the mitochondrial membrane potential (MMP) is a characteristic feature of cancer and cardiovascular disease. Therefore, it remains of crucial importance to develop new and improved fluorescent probes that are sensitive to the MMP, to report on mitochondrial health and function. Reported here are the design, synthesis, photophysical properties and biological characterisation of a series of BODIPY dyes, BODIPY-Mito-n, for mitochondria-targeted fluorescence imaging applications. Six BODIPY-Mito-n analogues were synthesised under mild conditions, and displayed excellent fluorescence quantum yields of between 0.59 and 0.72 in aqueous environments at physiological pH (pH = 7.4). The incorporation of poly(ethylene glycol) (PEG) chains to the triarylphosphonium cation moiety significantly improved the biocompatibility of the probes (BODIPY-Mito-6, IC50 > 50 µM). All BODIPY-Mito-n compounds demonstrated a high MMP-sensitive localisation in the mitochondria, with Pearson's correlation coefficients (PCC) of between 0.76 and 0.96. Compounds BODIPY-Mito-2 and BODIPY-Mito-6 revealed the highest sensitivity to the MMP, with a decrease in the emission intensity of 62% and 75%, respectively following MMP depolarisation. It is anticipated that the highest MMP sensitivity and enhanced biocompatibility of BODIPY-Mito-6 could lead to the development of new probes for mitochondrial imaging in the future.

Magnetic Sensor Angle Adjustment to Improve Corrosion under Insulation Detection.

A large portion of the pipe infrastructure used in the chemical processing industry is susceptible to corrosion under insulation (CUI). Eddy current-based magnetic sensing is one of the methods that can be used as an early detector of this corrosion. However, the large sensor-to-pipe distances used in this method, due to the presence of insulation, limits the sensitivity to corrosion. This paper will describe the development of instrumentation and methods based on eddy current sensing with thin-film magnetic sensors. In particular, it focuses on the influence of the sensor angle relative to the radial magnetic field. The influence of this parameter on the amplitude of the measured signal was investigated by both finite element simulations and experimental observations. The measured magnetic field was found to be highly sensitive to small changes in sensor angle, with the estimated depth of a defect changing at a rate of 11.2 mm/degree of sensor rotation for small angles. It is also shown that a sensor aligned with the radial direction should be avoided, with an optimal sensor angle between 0.5 and 4 degrees. With the sensor in this angle range, the simulations have shown it should be possible to resolve the depth of corrosion to a resolution of 0.1 mm.

A convenient synthesis of ferrocene-(ethynylphenyl)thioacetates.

Ferrocene is popular within the field of molecular electronics due to its well-defined electronic properties. However, where the conductance of highly-conjugated oligophenylethylenes has been widely studied, work on analogous ferrocenyl systems has been relatively rare, possibly due to difficulties associated with the synthesis of molecules containing terminal thioacetates, which are often used to bind molecules to metallic electrodes. Herein, a widely applicable synthetic methodology is demonstrated which can be used to synthesize a variety of conjugated ferrocene-alkyne systems terminated with thioacetates, including symmetric, asymmetric and multi-ferrocene systems. Conjugation of the ferrocene units to their terminal atoms is then shown through the use of both UV/Vis spectroscopy and cyclic voltammetry. This work paves the way for future studies and applications of conjugated ferrocene systems in the field of nanoelectronics.

Site-Specific 68Ga Radiolabeling of Trastuzumab Fab via Methionine for ImmunoPET Imaging.

Bioconjugates of antibodies and their derivatives radiolabeled with ß+-emitting radionuclides can be utilized for diagnostic PET imaging. Site-specific attachment of radioactive cargo to antibody delivery vectors provides homogeneous, well-defined immunoconjugates. Recent studies have demonstrated the utility of oxaziridine chemistry for site-specific labeling of methionine residues. Herein, we applied this approach to site-specifically radiolabel trastuzumab-derived Fab immunoconjugates with 68Ga, which can be used for in vivo PET imaging of HER2-positive breast cancer tumors. Initially, a reactive azide was introduced to a single solvent-accessible methionine residue in both the wild-type Fab and an engineered derivative containing methionine residue M74, utilizing the principles of oxaziridine chemistry. Subsequently, these conjugates were functionalized with a modified DFO chelator incorporating dibenzocyclooctyne. The resulting DFO-WT and DFO-M74 conjugates were radiolabeled with generator-produced [68Ga]Ga3+, to yield the novel PET radiotracers, [68Ga]Ga-DFO-WT and [68Ga]Ga-DFO-M74. In vitro and in vivo studies demonstrated that [68Ga]Ga-DFO-M74 exhibited a higher affinity for HER2 receptors. Biodistribution studies in mice bearing orthotopic HER2-positive breast tumors revealed a higher uptake of [68Ga]Ga-DFO-M74 in the tumor tissue, accompanied by rapid renal clearance, enabling clear delineation of tumors using PET imaging. Conversely, [68Ga]Ga-DFO-WT exhibited lower uptake and inferior image contrast compared to [68Ga]Ga-DFO-M74. Overall, the results demonstrate that the highly facile methionine-oxaziridine modification approach can be simply applied to the synthesis of stable and site-specifically modified radiolabeled antibody-chelator conjugates with favorable pharmacokinetics for PET imaging.

Evaluation of [18F]AlF-EMP-105 for Molecular Imaging of C-Met.

C-Met is a receptor tyrosine kinase that is overexpressed in a range of different cancer types, and has been identified as a potential biomarker for cancer imaging and therapy. Previously, a 68Ga-labelled peptide, [68Ga]Ga-EMP-100, has shown promise for imaging c-Met in renal cell carcinoma in humans. Herein, we report the synthesis and preliminary biological evaluation of an [18F]AlF-labelled analogue, [18F]AlF-EMP-105, for c-Met imaging by positron emission tomography. EMP-105 was radiolabelled using the aluminium-[18F]fluoride method with 46 ± 2% RCY and >95% RCP in 35-40 min. In vitro evaluation showed that [18F]AlF-EMP-105 has a high specificity for c-Met-expressing cells. Radioactive metabolite analysis at 5 and 30 min post-injection revealed that [18F]AlF-EMP-105 has good blood stability, but undergoes transformation-transchelation, defluorination or demetallation-in the liver and kidneys. PET imaging in non-tumour-bearing mice showed high radioactive accumulation in the kidneys, bladder and urine, demonstrating that the tracer is cleared predominantly as [18F]fluoride by the renal system. With its high specificity for c-Met expressing cells, [18F]AlF-EMP-105 shows promise as a potential diagnostic tool for imaging cancer.

Rapid short-pulses of focused ultrasound and microbubbles deliver a range of agent sizes to the brain.

Focused ultrasound and microbubbles can non-invasively and locally deliver therapeutics and imaging agents across the blood-brain barrier. Uniform treatment and minimal adverse bioeffects are critical to achieve reliable doses and enable safe routine use of this technique. Towards these aims, we have previously designed a rapid short-pulse ultrasound sequence and used it to deliver a 3 kDa model agent to mouse brains. We observed a homogeneous distribution in delivery and blood-brain barrier closing within 10 min. However, many therapeutics and imaging agents are larger than 3 kDa, such as antibody fragments and antisense oligonucleotides. Here, we evaluate the feasibility of using rapid short-pulses to deliver higher-molecular-weight model agents. 3, 10 and 70 kDa dextrans were successfully delivered to mouse brains, with decreasing doses and more heterogeneous distributions with increasing agent size. Minimal extravasation of endogenous albumin (66.5 kDa) was observed, while immunoglobulin (~ 150 kDa) and PEGylated liposomes (97.9 nm) were not detected. This study indicates that rapid short-pulses are versatile and, at an acoustic pressure of 0.35 MPa, can deliver therapeutics and imaging agents of sizes up to a hydrodynamic diameter between 8 nm (70 kDa dextran) and 11 nm (immunoglobulin). Increasing the acoustic pressure can extend the use of rapid short-pulses to deliver agents beyond this threshold, with little compromise on safety. This study demonstrates the potential for deliveries of higher-molecular-weight therapeutics and imaging agents using rapid short-pulses.

Quantum Interference and Contact Effects in the Thermoelectric Performance of Anthracene-Based Molecules.

We report on the single-molecule electronic and thermoelectric properties of strategically chosen anthracene-based molecules with anchor groups capable of binding to noble metal substrates, such as gold and platinum. Specifically, we study the effect of different anchor groups, as well as quantum interference, on the electric conductance and the thermopower of gold/single-molecule/gold junctions and generally find good agreement between theory and experiments. All molecular junctions display transport characteristics consistent with coherent transport and a Fermi alignment approximately in the middle of the highest occupied molecular orbital/lowest unoccupied molecular orbital gap. Single-molecule results are in agreement with previously reported thin-film data, further supporting the notion that molecular design considerations may be translated from the single- to many-molecule devices. For combinations of anchor groups where one binds significantly more strongly to the electrodes than the other, the stronger anchor group appears to dominate the thermoelectric behavior of the molecular junction. For other combinations, the choice of electrode material can determine the sign and magnitude of the thermopower. This finding has important implications for the design of thermoelectric generator devices, where both n- and p-type conductors are required for thermoelectric current generation.

Assembly, structure and thermoelectric properties of 1,1'-dialkynylferrocene 'hinges'.

Dialkynylferrocenes exhibit attractive electronic and rotational features that make them ideal candidates for use in molecular electronic applications. However previous works have primarily focussed on single-molecule studies, with limited opportunities to translate these features into devices. In this report, we utilise a variety of techniques to examine both the geometric and electronic structure of a range of 1,1'-dialkynylferrocene molecules, as either single-molecules, or as self-assembled monolayers. Previous single molecule studies have shown that similar molecules can adopt an 'open' conformation. However, in this work, DFT calculations, STM-BJ experiments and AFM imaging reveal that these molecules prefer to occupy a 'hairpin' conformation, where both alkynes point towards the metal surface. Interestingly we find that only one of the terminal anchor groups binds to the surface, though both the presence and nature of the second alkyne affect the thermoelectric properties of these systems. First, the secondary alkyne acts to affect the position of the frontier molecular orbitals, leading to increases in the Seebeck coefficient. Secondly, theoretical calculations suggested that rotating the secondary alkyne away from the surface acts to modulate thermoelectric properties. This work represents the first of its kind to examine the assembly of dialkynylferrocenes, providing valuable information about both their structure and electronic properties, as well as unveiling new ways in which both of these properties can be controlled.

Synthesis and anti-microbial activity of a new series of bis(diphosphine) rhenium(V) dioxo complexes.

Rhenium-based metallodrugs have recently been highlighted as promising candidates for new antibiotics to combat multi-drug resistant (MDR) pathogens. A new class of rhenium(V) dioxo complexes were prepared from readily accessible diphosphine ligands, and have been shown to possess potent activity against Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) alongside low human cell toxicity.

Multi-component self-assembled molecular-electronic films: towards new high-performance thermoelectric systems.

The thermoelectric properties of parallel arrays of organic molecules on a surface offer the potential for large-area, flexible, solution processed, energy harvesting thin-films, whose room-temperature transport properties are controlled by quantum interference (QI). Recently, it has been demonstrated that constructive QI (CQI) can be translated from single molecules to self-assembled monolayers (SAMs), boosting both electrical conductivities and Seebeck coefficients. However, these CQI-enhanced systems are limited by rigid coupling of the component molecules to metallic electrodes, preventing the introduction of additional layers which would be advantageous for their further development. These rigid couplings also limit our ability to suppress the transport of phonons through these systems, which could act to boost their thermoelectric output, without comprising on their impressive electronic features. Here, through a combined experimental and theoretical study, we show that cross-plane thermoelectricity in SAMs can be enhanced by incorporating extra molecular layers. We utilize a bottom-up approach to assemble multi-component thin-films that combine a rigid, highly conductive 'sticky'-linker, formed from alkynyl-functionalised anthracenes, and a 'slippery'-linker consisting of a functionalized metalloporphyrin. Starting from an anthracene-based SAM, we demonstrate that subsequent addition of either a porphyrin layer or a graphene layer increases the Seebeck coefficient, and addition of both porphyrin and graphene leads to a further boost in their Seebeck coefficients. This demonstration of Seebeck-enhanced multi-component SAMs is the first of its kind and presents a new strategy towards the design of thin-film thermoelectric materials.

To chelate thallium(I) - synthesis and evaluation of Kryptofix-based chelators for 201Tl.

While best known for its toxic properties, thallium has also been explored for applications in nuclear diagnostics and medicine. Indeed, [201Tl]TlCl has been used extensively for nuclear imaging in the past before it was superceded by other radionuclides such as 99mTc. One reason for this loss of interest is the severe lack of suitable organic chelators able to effectively coordinate ionic forms of Tl and deliver it to specific diseased tissue by means of attached biological vectors. Herein, we describe the synthesis and characterisation of a series of Kryptofix 222-based chelators that can be radiolabelled with 201Tl(I) in high radiochemical yields at ambient temperature. We demonstrate that from these simple chelators, targeted derivatives are readily accessible and describe the synthesis and preliminary biological evaluation of a PSMA-targeted 201Tl-labelled Kryptofix 222-peptide conjugate. While the Kryptofix system is demonstrably capable of binding the thallium cation, no PSMA-mediated cell-uptake could be detected with the PSMA conjugate, suggesting that this targeting moiety may not be ideal for use in conjunction with 201Tl.

N-Centered Tripodal Phosphine Re(V) and Tc(V) Oxo Complexes: Revisiting a [3 + 2] Mixed-Ligand Approach.

N-Triphos derivatives (NP3R, R = alkyl, aryl) and asymmetric variants (NP2RXR', R' = alkyl, aryl, X = OH, NR2, NRR') are an underexplored class of tuneable, tripodal ligands in relation to the coordination chemistry of Re and Tc for biomedical applications. Mixed-ligand approaches are a flexible synthetic route to obtain Tc complexes of differing core structures and physicochemical properties. Reaction of the NP3Ph ligand with the Re(V) oxo precursor [ReOCl3(PPh3)2] generated the bidentate complex [ReOCl3(κ2-NP2PhOHAr)], which possesses an unusual AA'BB'XX' spin system with a characteristic second-order NMR lineshape that is sensitive to the bi- or tridentate nature of the coordinating diphosphine unit. The use of the asymmetric NP2PhOHAr ligand resulted in the formation of both bidentate and tridentate products depending on the presence of base. The tridentate Re(V) complex [ReOCl2(κ3-NP2PhOAr)] has provided the basis of a new reactive "metal-fragment" for further functionalization in [3 + 2] mixed-ligand complexes. The synthesis of [3 + 2] complexes with catechol-based π-donors could also be achieved under one-pot, single-step conditions from Re(V) oxo precursors. Analogous complexes can also be synthesized from suitable 99Tc(V) precursors, and these complexes have been shown to exhibit highly similar structural properties through spectroscopic and chromatographic analysis. However, a tendency for the {MVO}3+ core to undergo hydrolysis to the {MVO2}+ core has been observed both in the case of M = Re and markedly for M = 99Tc complexes. It is likely that controlling this pathway will be critical to the generation of further stable Tc(V) derivatives.

Organometallic-functionalized interfaces for highly efficient inverted perovskite solar cells.

Further enhancing the performance and stability of inverted perovskite solar cells (PSCs) is crucial for their commercialization. We report that the functionalization of multication and halide perovskite interfaces with an organometallic compound, ferrocenyl-bis-thiophene-2-carboxylate (FcTc2), simultaneously enhanced the efficiency and stability of inverted PSCs. The resultant devices achieved a power conversion efficiency of 25.0% and maintained >98% of their initial efficiency after continuously operating at the maximum power point for 1500 hours under simulated AM1.5 illumination. Moreover, the FcTc2-functionalized devices passed the international standards for mature photovoltaics (IEC61215:2016) and have exhibited high stability under the damp heat test (85°C and 85% relative humidity).

Quantification of Angiogenesis in Laser Choroidal Neovascularization.

Murine laser-induced laser choroidal neovascularization is a widely used and robust model of wet (exudative) age-related macular degeneration (wAMD). wAMD is one of the leading causes of blindness in the Western world. In brief, a focused laser beam is used to penetrate Bruch's membrane, which separates the choriocapillaris (well-vascularized choroid layer) from the pigmented layers of the retina. Damage to the integrity of this membrane during diabetes leads to fluid accumulation and vascular invasion into the subretinal layers resulting in a progressive worsening of vision. Here we describe a 14-day model using untreated C57/Bl6 mice, but it is equally applicable to incorporation into transgenic studies and therapeutic agent development (such as eye drops), injection of therapeutic agents (including antibodies), and for longer time course studies. In vivo functional analysis or lesioned choroids can be studied with further immunohistochemical staining for further analyses.

Simple Gene Knockdown in Endothelial Cells Using Short Interfering RNA Oligonucleotides.

Cell transfection using short interfering RNAs (siRNAs) is a widely used technique to perform loss of function studies by "knocking down" genes of interest. Oftentimes, primary cells can be difficult to transfect, but here we provide a simple and robust method using cultured endothelial cells and routine transfection reagents. Knockdown studies can be used to complement overexpression studies and validate biochemical pathway analysis, as well as functional assays. The enclosed protocol will compliment other in vitro assays detailed in this edition.

Pathways and obstacles to social recovery following the elimination of SARS-CoV-2 from Aotearoa New Zealand: a qualitative cross-sectional study.

BACKGROUND: Many public health experts have claimed that elimination strategies of pandemic response allow 'normal social life' to resume. Recognizing that social connections and feelings of normality are important for public health, this study examines whether, and for whom, that goal is realized, and identifies obstacles that may inhibit its achievement. METHODS: Thematic analysis of narratives obtained via a qualitative cross-sectional survey of a community cohort in Aotearoa | New Zealand. RESULTS: A majority of participants reported that life after elimination was 'more or less the same' as before the pandemic. Some became more social. Nevertheless, a sizeable minority reported being less social, even many months after elimination. Key obstacles to social recovery included fears that the virus was circulating undetected and the enduring impact of lockdowns upon social relationships, personal habits and mental health. Within our sample, old age and underlying health conditions were both associated with a propensity to become less social. CONCLUSIONS: Elimination strategies can successfully allow 'normal social life' to resume. However, this outcome is not guaranteed. People may encounter difficulties with re-establishing social connections in Zero-COVID settings. Measures designed to overcome such obstacles should be an integral part of elimination strategies.