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Journal articleYue TTC, Teh JH, Aboagye E, et al., 2024,
Site-specific π-clamp-mediated radiosynthesis of 68Ga and 18F PET radiopharmaceuticals.
, Chem Commun (Camb)The π-clamp-mediated conjugation method, which enables site-specific modification of cysteine residues, is a promising strategy for developing well-defined radiolabelled biomolecules for positron emission tomography (PET) imaging. We have applied this method to site-specifically attach the macrocyclic chelators "NODA" and "NODAGA" to the somatostatin receptor 2-targeted peptide, octreotate. The resulting novel NODA-octreotate and NODAGA-octreotate compounds can be radiolabelled with either [18F]AlF- or [68Ga]Ga3+ respectively. In vivo PET imaging shows that the [68Ga]Ga3+-labelled derivative exhibits high stability and favourable pharmacokinetic properties.
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Journal articleWalter ERH, Leung PK-K, Lee LC-C, et al., 2024,
Potent BODIPY-based photosensitisers for selective mitochondrial dysfunction and effective photodynamic therapy.
, J Mater Chem B, Vol: 12, Pages: 10409-10415The 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.
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Journal articleGao D, Li B, Liu Q, et al., 2024,
Long-term stability in perovskite solar cells through atomic layer deposition of tin oxide.
, Science, Vol: 386, Pages: 187-192Robust 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.
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Journal articleMann P, Fairclough SM, Bourke S, et al., 2024,
Interface Engineering of Water-Dispersible Near-Infrared-Emitting CuInZnS/ZnSe/ZnS Quantum Dots.
, Cryst Growth Des, Vol: 24, Pages: 6275-6283, ISSN: 1528-7483We 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.
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Journal articleLi B, Gao D, Sheppard SA, et al., 2024,
Highly efficient and scalable p-i-n perovskite solar cells enabled by poly-metallocene interfaces
, Journal of the American Chemical Society, Vol: 146, Pages: 13391-13398, ISSN: 0002-7863Inverted 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.
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Journal articleWalter ERH, Lee LC-C, Leung PK-K, et al., 2024,
Mitochondria-targeting biocompatible fluorescent BODIPY probes
, Chemical Science, Vol: 15, Pages: 4846-4852, ISSN: 2041-6520An 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.
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Journal articleBennett TLR, Long NJ, 2023,
A convenient synthesis of ferrocene-(ethynylphenyl)thioacetates
, DALTON TRANSACTIONS, Vol: 52, Pages: 16465-16471, ISSN: 1477-9226 -
Journal articleYue TTC, Ge Y, Aprile FA, et al., 2023,
Site-Specific <SUP>68</SUP>Ga Radiolabeling of Trastuzumab Fab via Methionine for ImmunoPET Imaging
, BIOCONJUGATE CHEMISTRY, ISSN: 1043-1802 -
Journal articleAboagye E, Teh JH, Amgheib A, et al., 2023,
Evaluation of [18F]AlF-EMP-105 for molecular imaging of 2 C-Met
, Pharmaceutics, Vol: 15, Pages: 1-13, ISSN: 1999-4923C-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.
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Journal articleLim Kee Chang W, Chan T, Raguseo F, et al., 2023,
Rapid short-pulses of focused ultrasound and microbubbles deliver a range of agent sizes to the brain
, Scientific Reports, Vol: 13, ISSN: 2045-2322Focused 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.
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Journal articleHamill JM, Ismael A, Al-Jobory A, et al., 2023,
Quantum interference and contact effects in the thermoelectric performance of anthracene-based molecules
, The Journal of Physical Chemistry C: Energy Conversion and Storage, Optical and Electronic Devices, Interfaces, Nanomaterials, and Hard Matter, Vol: 127, Pages: 7484-7491, ISSN: 1932-7447We 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.
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Journal articleLong NJ, Bhargava S, 2022,
Professor Edward Abel, FRSC, CBE (1931-2021)
, DALTON TRANSACTIONS, Vol: 51, Pages: 16781-16783, ISSN: 1477-9226 -
Journal articleBourke S, Urbano L, Midson MM, et al., 2022,
Nearly monodispersed, emission-tuneable conjugated polymer nanoparticles
, SENSORS & DIAGNOSTICS, Vol: 1, Pages: 1185-1188 -
Journal articleCooper SM, Siakalli C, White AJP, et al., 2022,
Synthesis and anti-microbial activity of a new series of bis(diphosphine) rhenium(v) dioxo complexes
, DALTON TRANSACTIONS, Vol: 51, Pages: 12791-12795, ISSN: 1477-9226- Author Web Link
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Journal articleWilkinson LA, Bennett TLR, Grace IM, et al., 2022,
Assembly, structure and thermoelectric properties of 1,1 '-dialkynylferrocene 'hinges'
, Chemical Science, Vol: 13, Pages: 8380-8387, ISSN: 2041-6520Dialkynylferrocenes 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.
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Contact
Professor Nick Long
Email: n.long@imperial.ac.uk
Telephone: +44 (0)20 7594 5781
Location
501J
Molecular Sciences Research Hub
White City Campus
