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The Al18F-labeling approach offers a one-step access to radiofluorinated biomolecules by mimicking the labeling process for radiometals. Although these labeling conditions are considered to be mild compared to classic radiofluorinations, improvements of the chelating units have led to the discovery of (±)-H3RESCA, which allows Al18F-labeling already at ambient temperature. While the suitability of (±)-H3RESCA for functionalization and radiofluorination of proteins is well established, its use for small molecules or peptides is less explored. Herein, we advanced this acyclic pentadentate ligand by introducing an alkyne moiety for the late-stage functionalization of biomolecules via click chemistry. We show that in addition to Al18F-labeling, the cyclohexanediamine triazole (CHDT) moiety allows stable complexation of 68Ga and 111In. Three novel CHDT-functionalized PSMA inhibitors were synthesized and their Al18F-, 68Ga-, and 111In-labeled analogs were subjected to a detailed in vitro radiopharmacological characterization. Stability studies in vitro in human serum revealed among others a high kinetic inertness of all radiometal complexes. Furthermore, the Al18F-labeled PSMA ligands were characterized for their biodistribution in a LNCaP derived tumor xenograft mouse model by PET imaging. One radioligand, Al[18F]F-CHDT-PSMA-1, bearing a small azidoacetyl linker at the glutamate-urea-lysine motif, provided an in vivo performance comparable to that of [18F]PSMA-1007 but with even higher tumor-to-blood and tumor-to-muscle ratios at 120 min p.i. Overall, our results highlight the suitability of the novel CHDT moiety for functionalization and radiolabeling of small molecules or peptides with Al18F, 68Ga, and 111In and the triazole ring seems to entail favorable pharmacokinetic properties for molecular imaging purposes.
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Noninvasive molecular imaging of the PD-1/PD-L1 immune checkpoint is of high clinical relevance for patient stratification and therapy monitoring in cancer patients. Here we report nine small-molecule PD-L1 radiotracers with solubilizing sulfonic acids and a linker-chelator system, designed by molecular docking experiments and synthesized according to a new, convergent synthetic strategy. Binding affinities were determined both in cellular saturation and real-time binding assay (LigandTracer), revealing dissociation constants in the single digit nanomolar range. Incubation in human serum and liver microsomes proved in vitro stability of these compounds. Small animal PET/CT imaging, in mice bearing PD-L1 overexpressing and PD-L1 negative tumors, showed moderate to low uptake. All compounds were cleared primarily through the hepatobiliary excretion route and showed a long circulation time. The latter was attributed to strong blood albumin binding effects, discovered during our binding experiments. Taken together, these compounds are a promising starting point for further development of a new class of PD-L1 targeting radiotracers.
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Rationale: Small 225Ac-labeled prostate-specific membrane antigen (PSMA)-targeted radioconjugates have been described for targeted alpha therapy of metastatic castration-resistant prostate cancer. Transient binding to serum albumin as a highly abundant, inherent transport protein represents a commonly applied strategy to modulate the tissue distribution profile of such low-molecular-weight radiotherapeutics and to enhance radioactivity uptake into tumor lesions with the ultimate objective of improved therapeutic outcome. Methods: Two ligands mcp-M-alb-PSMA and mcp-D-alb-PSMA were synthesized by combining a macropa-derived chelator with either one or two lysine-ureido-glutamate-based PSMA- and 4-(p-iodophenyl)butyrate albumin-binding entities using multistep peptide-coupling chemistry. Both compounds were labeled with [225Ac]Ac3+ under mild conditions and their reversible binding to serum albumin was analyzed by an ultrafiltration assay as well as microscale thermophoresis measurements. Saturation binding studies and clonogenic survival assays using PSMA-expressing LNCaP cells were performed to evaluate PSMA-mediated cell binding and to assess the cytotoxic potency of the novel radioconjugates [225Ac]Ac-mcp-M-alb-PSMA and [225Ac]Ac-mcp-D-alb-PSMA, respectively. Biodistributions of both 225Ac-radioconjugates were investigated using LNCaP tumor-bearing SCID mice. Histological examinations of selected organs were performed to analyze the occurrence of necrosis using H&E staining, DNA damage via γH2AX staining and proliferation via Ki67 expression in the tissue samples. Results: Enhanced binding to serum components in general and to human serum albumin in particular was revealed for [225Ac]Ac-mcp-M-alb-PSMA and [225Ac]Ac-mcp-D-alb-PSMA, respectively. Moreover, the novel derivatives are highly potent PSMA ligands as their KD values in the nanomolar range (23.38 and 11.56 nM) are comparable to the reference radioconjugates [225Ac]Ac-mcp-M-PSMA (30.83 nM) and [225Ac]Ac-mcp-D-PSMA (10.20 nM) without albumin binders. The clonogenic activity of LNCaP cells after treatment with the 225Ac-labeled ligands was affected in a dose- and time-dependent manner, whereas the bivalent radioconjugate [225Ac]Ac-mcp-D-alb-PSMA has a stronger impact on the clonogenic cell survival than its monovalent counterpart [225Ac]Ac-mcp-M-alb-PSMA. Biodistribution studies performed in LNCaP tumor xenografts showed prolonged blood circulation times for both albumin-binding radioconjugates and a substantially increased tumor uptake (46.04 ± 7.77 %ID/g for [225Ac]Ac-mcp-M-alb-PSMA at 128 h p.i. and 153.48 ± 37.76 %ID/g at 168 h p.i. for [225Ac]Ac-mcp-D-alb-PSMA) with favorable tumor-to-background ratios. Consequently, a clear histological indication of DNA damage was discovered in the tumor tissues, whereas DNA double-strand break formation in kidney and liver sections was less pronounced. Conclusion: The modification of the PSMA-based 225Ac-radioconjugates with one or two albumin-binding entities resulted in an improved radiopharmacological behavior including a greatly enhanced tumor accumulation combined with a rather low uptake in most non-targeted organs combined with a high excretion via the kidneys.
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Radiofármacos , Albúmina Sérica , Animales , Masculino , Ratones , Humanos , Distribución Tisular , Línea Celular Tumoral , Ratones SCID , Radiofármacos/farmacocinética , LigandosRESUMEN
We report a nonadentate bispidine (3,7-diazabicyclo[3.3.1]nonane) that unveils the potential to bind theranostically relevant radionuclides, including indium-111, lutetium-177, and actinium-225 under mild labeling conditions. This radiopharmaceutical candidate allows the simultaneous application of imaging and treatment (radionuclide theranostics) without changing the type of the bioconjugate; that is, it allows the strong binding to an imaging and a therapeutic radionuclide by the same chelator. Since sophisticated coordination chemistry is required to achieve high thermodynamic and kinetic stability (inertness), it is not surprising that only a few chelators have been reported that are able to strongly bind several radionuclides to a satisfactory extent. Bispidine-derived ligands have proven to be ideal for di- and trivalent metal ions with generally fast complexation kinetics and high in vitro and in vivo stabilities. The presented (radio)complexes are formed under mild conditions (pH 6, <40 °C) and exhibit thermodynamic stability and inertness in human serum comparable to the corresponding DOTA complexes. The bispidine-based complexing agent was conjugated to a peptide, targeting somatostatin type 2 receptors (SSTR2), overexpressed on neuroendocrine tumors. The 177Lu- and 225Ac-labeled conjugates were investigated, considering their binding to two different SSTR2-positive cell lines, including the human pancreatic carcinoid tumor (BON-SSTR2+) and the murine pheochromocytoma cell line (MPC). The biodistribution and accumulation pattern in MPC tumor-bearing mice was also evaluated. The LuIII and AcIII complexes studied show how ligand structures can be optimized in general by extending the denticity and varying the donor set in order to allow for fast complex formation and medically relevant inertness.
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Quelantes , Medicina de Precisión , Animales , Ratones , Humanos , Quelantes/química , Distribución Tisular , Lutecio/química , Lutecio/uso terapéutico , Radioisótopos/química , Radiofármacos/químicaRESUMEN
With the interest in radiometal-containing diagnostic and therapeutic pharmaceuticals increasing rapidly, appropriate ligands to coordinate completely and stably said radiometals is essential. Reported here are two novel, bis(amido)bis(oxinate)diamine ligands, H2amidohox (2,2'-(ethane-1,2-diylbis(((8-hydroxyquinolin-2-yl)methyl)azanediyl))diacetamide) and H2amidoC3hox (2,2'-(propane-1,3-diylbis(((8-hydroxyquinolin-2-yl)methyl)azanediyl))diacetamide), that combine two 8-hydroxyquinoline and amide donor groups and differ by one carbon in their 1,2-ethylenediamine vs. 1,3-diaminopropane backbones, respectively. Both ligands have been thoroughly studied via metal complexation, solution thermodynamics and radiolabeling with three radiometal ions: [nat/64Cu]Cu2+, [nat/111In]In3+, and [nat/203Pb]Pb2+. X-ray crystallography determined the structures of the hexacoordinated Cu2+-ligand complexes, indicating a better fit of Cu2+ to the H2amidohox binding pocket. Concentration dependent radiolabeling with [64Cu]Cu2+ was successfully quantitative as low as 1 µM with H2amidohox and 10 µM with H2amidoC3hox within 5 min at room temperature. However, [64Cu][Cu(amidohox)] maintained higher kinetic inertness against a superoxide dismutase enzyme-challenge assay and ligand challenges compared to the [64Cu][Cu(amidoC3hox)] counterpart. Similarly, H2amidohox had significantly higher radiochemical conversion with both [111In]In3+ (97% at 1 µM) and [203Pb]Pb2+ (97% at 100 µM) under mild conditions compared to H2amidoC3hox (76% with [111In]In3+ at 1 µM and 0% with [203Pb]Pb2+). By studying non-radioactive and radioactive complexation with both ligands, a comprehensive understanding of the coordination differences between two- and threecarbon diamine backbones is discussed. Overall, the ethylenediamine backbone of H2amidohox proves to be superior in rapid, mild radiolabeling and kinetic inertness towards competing ligands and proteins.
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Diaminas , Plomo , Carbono , Cobre/química , Cristalografía por Rayos X , Ligandos , Nanomedicina TeranósticaRESUMEN
A new versatile chelating ligand for intermediate size and softness radiometals [64Cu]Cu2+ and [111In]In3+, H2pyhox, was synthesized by introducing pyridine as a new donor moiety to complement 8-hydroxyquinoline on an ethylenediamine backbone. The combination of pyridine and oxine as donor sets was explored through structural analysis, and crystals of the three metal complexes with Cu2+, La3+, and In3+ demonstrate how the ligand adapts to accommodate metal ions of different sizes and charge. Exhaustive in-batch UV solution studies characterized the protonation constants of the free ligand as well as the formation constants of the metal complexes with Cu2+, In3+, and La3+. Preliminary concentration-dependent radiolabeling studies with [111In]In3+ and [64Cu]Cu2+ show the robustness of H2pyhox to successfully coordinate both radiometals under mild conditions (<15 min, room temperature, pH 6). H2pyhox is the first oxinate ligand to successfully radiolabel [225Ac]Ac3+, albeit only at high concentrations (0.1-1 mM) with gentle heating to 37 °C. Whole serum, protein, and ligand challenge assays further demonstrate the kinetic inertness of the [111In]In3+ and [64Cu]Cu2+ radiometal-ligand complexes, confirming H2pyhox to be a promising versatile radiopharmaceutical chelator.
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We show the synthesis of an inâ vivo stable mercury compound with functionality suitable for radiopharmaceuticals. The designed cyclic bisarylmercury was based on the water tolerance of organomercurials, higher bond dissociation energy of Hg-Ph to Hg-S, and the experimental evidence that acyclic structures suffer significant cleavage of one of the Hg-R bonds. The bispidine motif was chosen for its inâ vivo stability, chemical accessibility, and functionalization properties. Radionuclide production results in 197(m) HgCl2 (aq), so the desired mercury compound was formed via a water-tolerant organotin transmetallation. The Hg-bispidine compound showed high chemical stability in tests with an excess of sulfur-containing competitors and high inâ vivo stability, without any observable protein interaction by human serum assay, and good organ clearance demonstrated by biodistribution and SPECT studies in rats. In particular, no retention in the kidneys was observed, typical of unstable mercury compounds. The nat Hg analogue allowed full characterization by NMR and HRMS.
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Mercurio/química , Compuestos Organometálicos/química , Radiofármacos/química , Nanomedicina Teranóstica , Estabilidad de Medicamentos , Humanos , Radioisótopos de Mercurio , Compuestos Organometálicos/sangre , Compuestos Organometálicos/síntesis química , Radiofármacos/sangre , Radiofármacos/síntesis químicaRESUMEN
Currently, targeted alpha therapy is one of the most investigated topics in radiopharmaceutical cancer management. Especially, the alpha emitter 225Ac has excellent nuclear properties and is gaining increasing popularity for the treatment of various tumor entities. We herein report on the synthesis of two universal 225Ac-chelators for mild condition radiolabeling and binding to conjugate molecules of pharmacological interest via the copper-mediated click chemistry. A convenient radiolabeling procedure was investigated as well as the complex stability proved for both chelators and two PSMA (prostate-specific membrane antigen)-targeting model radioconjugates. Studies regarding affinity and cell survival were performed on LNCaP cells followed by biodistribution studies, which were performed using LNCaP tumor-bearing mice. High efficiency radiolabeling for all conjugates was demonstrated. Cell binding studies revealed a fourfold lower cell affinity for the PSMA radioconjugate with one targeting motif compared to the radioconjugate owing two targeting motifs. Additionally, these differences were verified by in vitro cell survival evaluation and biodistribution studies, both showing a higher cell killing efficiency for the same dose, a higher tumor uptake (15%ID/g) and a rapid whole body clearance after 24 h. The synthesized chelators will overcome obstacles of lacking stability and worse labeling needs regarding 225Ac complexation using the DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid) chelator. Moreover, the universal functionalization expands the coverage of these chelators in combination with any sensitive bio(macro)molecule, thus improving treatment of any addressable tumor target.
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Invited for this month's cover is the group of Kristof Zarschler at the University of Dresden, Germany. Read the full text of their Full Paper at 10.1002/open.202000126.
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Sulfato de Bario/química , Portadores de Fármacos/química , Nanopartículas del Metal/química , Metales Pesados/química , Radioisótopos/química , Radiofármacos/química , Humanos , Tamaño de la Partícula , Medicina de PrecisiónRESUMEN
The treatment of cancer patients with α-particle-emitting therapeutics continues to gain in importance and relevance. The range of radiopharmaceutically relevant α-emitters is limited to a few radionuclides, as stable chelators or carrier systems for safe transport of the radioactive cargo are often lacking. Encapsulation of α-emitters into solid inorganic systems can help to diversify the portfolio of candidate radionuclides, provided, that these nanomaterials effectively retain both the parent and the recoil daughters. We therefore focus on designing stable and defined nanocarrier-based systems for various clinically relevant radionuclides, including the promising α-emitting radionuclide 224Ra. Hence, sub-10â nm barium sulfate nanocontainers were prepared and different radiometals like 89Zr, 111In, 131Ba, 177Lu or 224Ra were incorporated. Our system shows stabilities of >90 % regarding the radiometal release from the BaSO4 matrix. Furthermore, we confirm the presence of surface-exposed amine functionalities as well as the formation of a biomolecular corona.
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Sulfato de Bario/química , Portadores de Fármacos/química , Nanopartículas del Metal/química , Metales Pesados/química , Radioisótopos/química , Radiofármacos/química , Alendronato/química , Sangre/metabolismo , Portadores de Fármacos/metabolismo , Estabilidad de Medicamentos , Humanos , Tamaño de la Partícula , Medicina de Precisión , Corona de Proteínas/química , Radiofármacos/metabolismoRESUMEN
[44/47Sc]Sc3+, [68Ga]Ga3+, and [111In]In3+ are the three most attractive trivalent smaller radiometalnuclides, offering a wide range of distinct properties (emission energies and types) in the toolbox of nuclear medicine. In this study, all three of the metal ions are successfully chelated using a new oxine-based hexadentate ligand, H3glyox, which forms thermodynamically stable neutral complexes with exceptionally high pM values [pIn (34) > pSc (26) > pGa (24.9)]. X-ray diffraction single crystal structures with stable isotopes revealed that the ligand is highly preorganized and has a perfect fit to size cavity to form [Sc(glyox)(H2O)] and [In(glyox)(H2O)] complexes. Quantitative radiolabeling with gallium-68 (RCY > 95%, [L] = 10-5 M) and indium-111 (RCY > 99%, [L] = 10-8 M) was achieved under ambient conditions (RT, pH 7, and 15 min) with very high apparent molar activities of 750 MBq/µmol and 650 MBq/nmol, respectively. Preliminary quantitative radiolabeling of [44Sc]ScCl3 (RCY > 99%, [L] = 10-6 M) was fast at room temperature (pH 7 and 10 min). In vitro experiments revealed exceptional stability of both [68Ga]Ga(glyox) and [111In]In(glyox) complexes against human serum (transchelation <2%) and its suitability for biological applications. Additionally, on chelation with metal ions, H3glyox exhibits enhanced fluorescence, which was employed to determine the stability constants for Sc(glyox) in addition to the in-batch UV-vis spectrophotometric titrations; as a proof-of-concept these complexes were used to obtain fluorescence images of live HeLa cells using Sc(glyox) and Ga(glyox), confirming the viability of the cells. These initial investigations suggest H3glyox to be a valuable chelator for radiometal-based diagnosis (nuclear and optical imaging) and therapy.
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Quelantes/farmacología , Complejos de Coordinación/farmacología , Colorantes Fluorescentes/farmacología , Oximas/farmacología , Radiofármacos/farmacología , Quelantes/síntesis química , Complejos de Coordinación/sangre , Complejos de Coordinación/química , Estabilidad de Medicamentos , Colorantes Fluorescentes/química , Radioisótopos de Galio/química , Células HeLa , Humanos , Radioisótopos de Indio/química , Marcaje Isotópico , Ligandos , Microscopía Fluorescente/métodos , Oximas/síntesis química , Prueba de Estudio Conceptual , Radioisótopos/química , Radiofármacos/sangre , Radiofármacos/química , Escandio/química , TermodinámicaRESUMEN
Active tumor targeting involves the decoration of nanomaterials (NMs) with oncotropic vector biomolecules that selectively recognize certain antigens on malignant cells or in the tumor microenvironment. This strategy can facilitate intracellular uptake of NM through specific interactions such as receptor-mediated endocytosis and can lead to prolonged retention in the malignant tissues by preventing rapid efflux from the tumor. Here, the design of actively targeting, renally excretible bimodal dendritic polyglycerols (dPGs) for diagnostic cancer imaging is described. Single-domain antibodies (sdAbs) specifically binding to the epidermal growth factor receptor (EGFR) are employed herein as targeting warheads owing to their small size and high affinity for their corresponding antigen. The dPGs equipped with EGFR-targeting feature are compared head-to-head with their nontargeting counterparts in terms of interaction with EGFR-overexpressing cells in vitro as well as accumulation at receptor-positive tumors in vivo. Experimental results reveal a higher specificity and preferential tumor accumulation for the α-EGFR dPGs, resulting from the introduction of active targeting capabilities on their backbone. These results highlight the potential for improving the tumor uptake properties of dPGs by strategic use of sdAb functionalization, which can ultimately prove useful to the development of ultrasmall NM with highly specific tumor accumulation.
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Técnicas y Procedimientos Diagnósticos , Glicerol , Neoplasias , Polímeros , Anticuerpos de Dominio Único , Endocitosis , Receptores ErbB/metabolismo , Glicerol/análisis , Células Hep G2 , Humanos , Nanoestructuras , Neoplasias/diagnóstico por imagen , Polímeros/análisis , Unión Proteica , Anticuerpos de Dominio Único/metabolismo , Microambiente TumoralRESUMEN
Bifunctional chelators as parts of modular metal-based radiopharmaceuticals are responsible for stable complexation of the radiometal ion and for covalent linkage between the complex and the targeting vector. To avoid loss of complex stability, the bioconjugation strategy should not interfere with the radiometal chelation by occupying coordinating groups. The C9 position of the very stable CuII chelator 3,7-diazabicyclo[3.3.1]nonane (bispidine) is virtually predestined to introduce functional groups for facile bioconjugation as this functionalisation does not disturb the metal binding centre. We describe the preparation and characterisation of a set of novel bispidine derivatives equipped with suitable functional groups for diverse bioconjugation reactions, including common amine coupling strategies (bispidine-isothiocyanate) and the Cu-free strain-promoted alkyne-azide cycloaddition. We demonstrate their functionality and versatility in an exemplary way by conjugation to an antibody-based biomolecule and validate the obtained conjugate in vitro and in vivo.
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Compuestos Bicíclicos Heterocíclicos con Puentes/química , Quelantes/química , Cobre/química , Radiofármacos/química , Animales , Compuestos Bicíclicos Heterocíclicos con Puentes/síntesis química , Línea Celular Tumoral , Cetuximab/química , Complejos de Coordinación/síntesis química , Complejos de Coordinación/química , Reacción de Cicloadición , Humanos , Ratones , Microscopía Fluorescente , Neoplasias/diagnóstico por imagen , Tomografía de Emisión de Positrones , Radiofármacos/síntesis química , Trasplante HeterólogoRESUMEN
There is a current surge of interest in the development of novel photosensitizers (PSs) for photodynamic therapy (PDT), as those currently approved are not completely ideal. Among the tested compounds, we have previously investigated the use of RuII polypyridyl complexes with a [Ru(bipy)2 (dppz)]2+ and [Ru(phen)2 (dppz)]2+ scaffold (bipy=2,2'-bipyridine; dppz=dipyrido[3,2-a:2',3'-c]phenazine; phen=1,10-phenanthroline). These complexes selectively target DNA. However, because DNA is ubiquitous, it would be of great interest to increase the selectivity of our PDT PSs by linking them to a targeting vector in view of targeted PDT. Herein, we present the synthesis, characterization, and in-depth photophysical evaluation of a nanobody-containing RuII polypyridyl conjugate selective for the epidermal growth factor receptor (EGFR) in view of targeted PDT. Using ICP-MS and confocal microscopy, we could demonstrate that our conjugate has high selectivity for the EGFR receptor, which is a crucial oncological target because it is overexpressed and/or deregulated in a variety of solid tumors. However, in contrast to expectations, this conjugate was found to not produce reactive oxygen species (ROS) in cancer cells and is therefore not phototoxic.
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Neoplasias/tratamiento farmacológico , Compuestos Organometálicos , Fotoquimioterapia , Fármacos Fotosensibilizantes , Compuestos Policíclicos , Rutenio/química , Línea Celular Tumoral , Receptores ErbB/antagonistas & inhibidores , Humanos , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Fármacos Fotosensibilizantes/síntesis química , Fármacos Fotosensibilizantes/química , Compuestos Policíclicos/síntesis química , Compuestos Policíclicos/químicaRESUMEN
Tetranuclear chiral Cu(ii)-Schiff-base complexes S-1 and R-1, were synthesised using enantiomerically pure (S)-(H2vanPheol) and (R)-(H2vanPheol) ligands respectively in the ratio of 1 : 1 of Cu(NO3)2 to (S/R)-(H2vanPheol) in MeOH at room temperature. A pair of polynuclear chiral Cu(ii)-cluster complexes were characterized using single-crystal X-ray diffraction, elemental analysis, infrared and CD spectroscopy. The results revealed the importance of these chiral ligands encouraging the arrangement of copper metal in non-centrosymmetric polar packing. The potential of the novel [Cu4(S/R-vanPheol)2(S/R-HvanPheol)2(CH3OH)2](NO3)2 complexes as biologically active compounds was assessed in particular regarding their anti-proliferative and anti-microbial properties.
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We demonstrate a novel strategy for preparing hydrophilic upconverting nanoparticles (UCNPs) by harnessing the photocrosslinking ability of diacetylenes. Replacement of the hydrophobic oleate coating on the UCNPs with 10,12-pentacosadiynoic acid, followed by overcoating with diacetylene phospholipid and subsequent photocrosslinking under 254â nm irradiation produces water-dispersible polydiacetylene-coated UCNPs. These UCNPs resist the formation of a biomolecular corona and show great colloidal stability. Furthermore, amine groups on the diacetylene phospholipid allow for functionalisation of the UCNPs with, for example, radiolabels or targeting moieties. These results demonstrate that this new surface-coating method has great potential for use in the preparation of UCNPs with improved biocompatibility.
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Pure hexagonal (ß-phase) NaYF4-based hydrophobic upconverting nanoparticles (UCNPs) were surface-modified with O-phospho-l-threonine (OPLT), alendronic acid, and PEG-phosphate ligands to generate water-dispersible UCNPs. Fourier-transform infrared (FTIR) spectroscopy was used to establish the presence of the ligands on the UCNP surface. These UCNPs exhibit great colloidal stability and a near-neutral surface at physiological pH, as confirmed by dynamic light scattering (DLS) and zeta potential (ζ) measurements, respectively. The particles also display excellent long-term stability, with no major adverse effect on the size of UCNPs when kept at pH 7.4. Upon exposure to human serum, PEG-phosphate- and alendronate-coated UCNPs showed no formation of biomolecular corona, as confirmed by SDS-PAGE analysis. The photophysical properties of water-dispersible UCNPs were investigated using steady-state as well as time-resolved luminescence spectroscopy, under excitation at ca. 800 nm. The results clearly show that the UCNPs demonstrate bright upconversion (UC) luminescence. Furthermore, the presence of reactive groups on the NPs, such as free amine groups in alendronate-coated UCNPs, enables further functionalisation of UCNPs with, for example, small molecules, peptides, proteins, and antibodies. Overall these protein corona resistant UCNPs show great biocompatibility and are worthy of further investigation as potential new biomaging probes.
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Ingeniería Biomédica , Nanopartículas/química , Nanotecnología , Alendronato/análogos & derivados , Alendronato/química , Aminas/química , Fluoruros/química , Humanos , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Ligandos , Luminiscencia , Polietilenglicoles/química , Suero/química , Propiedades de Superficie , Tirosina/análogos & derivados , Tirosina/química , Agua/química , Itrio/químicaRESUMEN
Dendritic polyglycerols (dPG) are water soluble, polyether-based nanomaterials which hold great potential in diagnostic as well as therapeutic applications. In order to translate them for in vivo applications, a systematic assessment regarding their cell and tissue interactions as well as their metabolic fate in vivo is a crucial step. Herein, we explore the structure-activity relationship of three different sizes (ca. 3, 5, and 10 nm) of neutral dendritic polyglycerol (dPG) and their corresponding negatively charged sulfate analogs (dPGS) on their in vitro and in vivo characteristics. Cellular metabolic activity was studied in A431 and HEK293 cells. Biomolecular corona formation was determined using an electrophoretic mobility shift assay, which showed an increased protein binding of the dPGS even with serum concentrations as low as 20%. An in situ technique, microscale thermophoresis, was employed to address the binding affinities of these nanomaterials with serum proteins such as serum albumin, apo-transferrin, and fibrinogen. In addition, nanoparticle-cell interactions were studied in differentiated THP-1 cells which showed a charge dependent scavenger receptor-mediated uptake. In line with this data, detailed biodistribution and small animal PET imaging studies in Wistar rats using 68Ga-labeled dPG-/dPGS-NOTA conjugates showed that the neutral dPG-NOTA conjugates were quantitatively excreted via the kidneys with a subsequent hepatobiliary excretion with an increase in their size, whereas the polysulfated analogs (dPGS-NOTA) were sequestered preferentially in the liver and kidneys irrespective of their size. Taken together, this systematic study accentuates that the pharmacokinetics of dPGs is critically dependent on the overall size and charge and can be, fine-tuned for the intended requirements in nano-theranostics.
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The peptide HsTX1[R14A] is a potent and selective blocker of the voltage-gated potassium channel Kv1.3, which is a highly promising target for the treatment of autoimmune diseases and other conditions. In order to assess the biodistribution of this peptide, it was conjugated with NOTA and radiolabelled with copper-64. [64Cu]Cu-NOTA-HsTX1[R14A] was synthesised in high radiochemical purity and yield. The radiotracer was evaluated in vitro and in vivo. The biodistribution and PET studies after intravenous and subcutaneous injections showed similar patterns and kinetics. The hydrophilic peptide was rapidly distributed, showed low accumulation in most of the organs and tissues, and demonstrated high molecular stability in vitro and in vivo. The most prominent accumulation occurred in the epiphyseal plates of trabecular bones. The high stability and bioavailability, low normal-tissue uptake of [64Cu]Cu-NOTA-HsTX1[R14A], and accumulation in regions of up-regulated Kv channels both in vitro and in vivo demonstrate that HsTX1[R14A] represents a valuable lead for conditions treatable by blockade of the voltage-gated potassium channel Kv1.3. The pharmacokinetics shows that both intravenous and subcutaneous applications are viable routes for the delivery of this potent peptide.
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Canal de Potasio Kv1.3/antagonistas & inhibidores , Péptidos , Bloqueadores de los Canales de Potasio , Administración Intravenosa , Animales , Línea Celular , Inyecciones Subcutáneas , Masculino , Ratones , Péptidos/farmacocinética , Péptidos/farmacología , Bloqueadores de los Canales de Potasio/farmacocinética , Bloqueadores de los Canales de Potasio/farmacología , Ratas , Ratas WistarRESUMEN
Cancer is one of the leading non-communicable diseases with highest mortality rates worldwide. About half of all cancer patients receive radiation treatment in the course of their disease. However, treatment outcome and curative potential of radiotherapy is often impeded by genetically and/or environmentally driven mechanisms of tumor radioresistance and normal tissue radiotoxicity. While nanomedicine-based tools for imaging, dosimetry and treatment are potential keys to the improvement of therapeutic efficacy and reducing side effects, radiotherapy is an established technique to eradicate the tumor cells. In order to progress the introduction of nanoparticles in radiooncology, due to the highly interdisciplinary nature, expertise in chemistry, radiobiology and translational research is needed. In this report recent insights and promising policies to design nanotechnology-based therapeutics for tumor radiosensitization will be discussed. An attempt is made to cover the entire field from preclinical development to clinical studies. Hence, this report illustrates (1) the radio- and tumor-biological rationales for combining nanostructures with radiotherapy, (2) tumor-site targeting strategies and mechanisms of cellular uptake, (3) biological response hypotheses for new nanomaterials of interest, and (4) challenges to translate the research findings into clinical trials.