Homo- and hetero-difunctionalized ß-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry.

The regioselective difunctionalization of cyclodextrins (CDs) leading to derivatives amenable to further transformations is a daunting task due to challenging purification and unambiguous characterization of the obtained regioisomers with similar physicochemical properties. The primary-side homo-difunctionalization of ß-CD can lead to three regioisomers, while the hetero-difunctionalization can generate three pairs of pseudoenantiomers. Previously, approaches with several synthetic steps, expensive reagents, high purification demands and low yields of the products have been employed. Herein we present direct, short and efficient primary-side difunctionalization strategies featuring reproducibility, ease of product purification, scalability of the reactions and versatility of the substituents introduced. Specifically, the prepared ditosylated ß-CDs were separated using preparative reversed-phase column chromatography and their structures were elucidated by NMR experiments. Azidation led to the corresponding pure diazido regioisomers. Direct monotosylation of 6-monoazido-ß-CD or monoazidation of the single regioisomers 6A,6X-ditosyl-ß-CDs afforded hetero-difunctionalized 6A-monoazido-6X-tosyl-ß-CDs in significant yields. Overall, the single regioisomers, 6A,6X-ditosyl-, 6A,6X-diazido- and 6A-monoazido-6X-monotosyl-ß-CD were prepared in one or two steps and purified in multigram scale thus opening the way towards further selective and orthogonal functionalizations of ß-CD hosts.

Molecular recognition of N-acetyltryptophan enantiomers by ß-cyclodextrin.

The enantioselectivity of ß-cyclodextrin (ß-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that ß-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state, only ß-CD-L-NAcTrp crystallizes readily from aqueous solutions as a dimeric complex (two hosts enclosing two guest molecules). In contrast, crystals of the complex ß-CD-D-NAcTrp were never obtained, although numerous conditions were tried. In aqueous solution, the orientation of the guest in both complexes is different than in the ß-CD-L-NAcTrp complex in the crystal. Overall, the study shows that subtle differences observed between the ß-CD-L,D-NAcTrp complexes in aqueous solution are magnified at the onset of crystallization, as a consequence of accumulation of many soft host-guest interactions and of the imposed crystallographic order, thus resulting in very dissimilar propensity of each enantiomer to produce crystals with ß-CD.

Photochemical internalization of tamoxifens transported by a "Trojan-horse" nanoconjugate into breast-cancer cell lines.

Photochemical internalization (PCI) has shown great promise as a therapeutic alternative for targeted drug delivery by light-harnessed activation. However, it has only been applicable to therapeutic macromolecules or medium-sized molecules. Herein we describe the use of an amphiphilic, water-soluble porphyrin-ß-cyclodextrin conjugate (mTHPP-ßCD) as a "Trojan horse" to facilitate the endocytosis of CD-guest tamoxifens into breast-cancer cells. Upon irradiation, the porphyrin core of mTHPP-ßCD expedited endosomal membrane rupture and tamoxifen release into the cytosol, as documented by confocal microscopy. The sustained complexation of mTHPP-ßCD with tamoxifen was corroborated by 2D NMR spectroscopy and FRET studies. Following the application of PCI protocols with 4-hydroxytamoxifen (4-OHT), estrogen-receptor ß-positive (Erß+, but not ERß-) cell groups exhibited extensive cytotoxicity and/or growth suspension even at 72 h after irradiation.

A versatile δ-aminolevulinic acid (ΑLA)-cyclodextrin bimodal conjugate-prodrug for PDT applications with the help of intracellular chemistry.

Grafting of δ-aminolevulinic acid (1) moieties on the narrow periphery of a ß-cyclodextrin (ß-CD) derivative through hydrolysable bonds was implemented, in order to generate a water-soluble, molecular/drug carrier with the capacity to undergo intracellular transformation into protoporphyrin IX (PpIX), an endogenous powerful photosensitizer for photodynamic therapy (PDT). The water-soluble derivative 2 was prepared by esterifying δ-azidolevulinic acid with heptakis(6-hydroxyethylamino-6-deoxy)-ß-cyclodextrin, with an average degree of substitution, DS = 3. Delivery of water-soluble, colorless 2 to cells resulted in intense red fluorescence registered by confocal microscopy, evidently due to the engagement of the intracellular machinery towards formation of PpIX. Conjugate 2 was further complexed with a fluorescein-labeled model guest molecule which was successfully transported into the cells, thereby demonstrating the bimodal action of the derivative. The present work shows the versatility of CDs in smart applications and constitutes advancement to our previously shown PpIX-ß-CD conjugation both in terms of water solubility and lack of aggregation.

Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability.

ß-Cyclodextrin (ß-CD) dimers have been prepared using the bioorthogonal Staudinger ligation for the first time. In addition to a known linker, methyl 2-(diphenylphosphanyl)terephthalate, a doubly active linker was specifically developed that enabled connection of two ß-CD units in a single step and in aqueous/organic media, under mild conditions and with good yields. A three-carbon spacer between the ß-CD torus and the azido group was required for facile dimer formation. The products, as studied by NMR spectroscopy, were found to adopt closed conformations by intramolecular self-inclusion. On the other hand, association via intermolecular binding was also observed in aqueous solution, confirmed by DOSY NMR experiments. Despite self-inclusion, the ß-CD cavities were capable of guest encapsulation, as shown by titration experiments: the binding constant with 1-adamantylamine was similar to that of natural ß-CD. Theoretical calculations for isolated molecules (PM3 level of theory) and in the presence of solvent [water, PM3(COSMO)] as well as DFT calculations suggested that the compounds prefer to adopt conformations which bring the phenyl groups either inside the ß-CD cavity (inclusion) or over its narrow side (vicinal). Thus, Staudinger ligation could be the method of choice for linking CDs exhibiting (i) ease of preparation in aqueous media, in short steps, under mild conditions and in good yields, (ii) satisfactory aqueous solubility and independent binding capacity of the cavities.

Amphiphilic Chlorin-ß-cyclodextrin Conjugates in Photo-Triggered Drug Delivery: The Role of Aggregation.

Conjugates of chlorins with ß-cyclodextrin connected either directly or via a flexible linker were prepared. In aqueous medium these amphiphilic conjugates were photostable, produced singlet oxygen at a rate similar to clinically used temoporfin and formed irregular nanoparticles via aggregation. Successful loading with the chemotherapeutic drug tamoxifen was evidenced in solution by the UV-Vis spectral changes and dynamic light scattering profiles. Incubation of MCF-7 cells with the conjugates revealed intense spotted intracellular fluorescence suggestive of accumulation in endosome/lysosome compartments, and no dark toxicity. Incubation with the tamoxifen-loaded conjugates revealed also practically no dark toxicity. Irradiation of cells incubated with empty conjugates at 640 nm and 4.18 J/cm2 light fluence caused >50 % cell viability reduction. Irradiation following incubation with tamoxifen-loaded conjugates resulted in even higher toxicity (74 %) indicating that the produced reactive oxygen species had triggered tamoxifen release in a photochemical internalization (PCI) mechanism. The chlorin-ß-cyclodextrin conjugates displayed less-lasting effects with time, compared to the corresponding porphyrin-ß-cyclodextrin conjugates, possibly due to lower tamoxifen loading of their aggregates and/or their less effective lodging in the cell compartments' membranes. The results suggest that further to favorable photophysical properties, other parameters are important for the in vitro effectiveness of the photodynamic systems.

Small anticancer drug release by light: Photochemical internalization of porphyrin-ß-cyclodextrin nanoparticles.

Aiming to engineer simple, neutral, strongly amphiphilic photoactive nanoparticles (NPs) to specifically target cancer cell lysosomes for drug transport and light-controlled release, new conjugates of ß-cyclodextrin with highly hydrophobic triphenylporphyrin bearing different alkyl chains, were synthesized. Although differently sized, all conjugates self-assemble into ~60 nm NPs in water and display similar photoactivity. The NPs target selectively the lysosomes of breast adenocarcinoma MCF-7 cells, embedding in vesicular membranes, as experiments with model liposomes indicate. Either empty or drug-loaded, the NPs lack dark toxicity for 48 h. They bind with differently structured anticancer drugs tamoxifen and gemcitabine as its N-adamantyl derivative. Red light irradiation of cells incubated with drug-loaded NPs results in major reduction of viability (>85 %) for 48 h displaying significant synergy of photo-chemotoxicity, as opposed to empty NPs, and to loaded non-irradiated NPs, in manifestation of photochemical internalization (PCI). Our approach expands the field of PCI into different small molecule chemotherapeutics.

Metal-binding cyclodextrins: Synthesis and complexation with Zn2+ and Ga3+ cations towards antimicrobial applications.

Highly resistant bacteria producing metallo-ß-lactamases (MBLs) to evade ß-lactam antibiotics, constitute a major cause of life-threatening infections world-wide. MBLs exert their hydrolytic action via Zn2+ cations in their active center. Presently, there are no approved drugs to target MBLs and combat the associated antimicrobial resistance (AMR). Towards this issue, we have prepared a family of cyclodextrins substituted with iminodiacetic acid (IDA) on their narrow side, while the wider side is either unmodified or per-2,3-O-methylated. The molecules form strong coordination complexes with Zn2+ or Ga3+ cations in aqueous solution. Free and metal-complexed compounds have been thoroughly characterized regarding structures, pH-dependent ionization states, distribution of species in solution, pKa values and metal-binding constants. At neutral pH the multi-anionic hosts bind up to four Zn2+ or Ga3+ cations. In vitro, 50 µΜ of the compounds achieve complete re-sensitization of MBL-producing Gram-negative clinical bacterial strains resistant to the carbapenems imipenem and meropenem. Moreover, the radioactive complex [67Ga]Ga-ß-IDACYD prepared, displays high radiochemical purity, sufficient stability both overtime and in the presence of human plasma apo-transferrin, thus providing an invaluable tool for future biodistribution and pharmacokinetic studies of ß-IDACYDin vivo, prerequisites for the development of therapeutic protocols.

A guanidino-γ-cyclodextrin superdimer generates a twin receptor for phosphate dimers assembled by anti-electrostatic hydrogen bonds.

Octakis-6-guadinidino-γ-cyclodextrin (gguan) hydrochloride in the presence of phosphates crystallises from aqueous solution in the unprecedented form of a superdimer (dimer-within-a-dimer). The self-assembly exposes four circular octa-guanidinium regions that bind and stabilise discrete H-bonded phosphate anion dimers. The small (∼2 nm) gguan-phosphate assembly is preorganised and stable in aqueous solution, as demonstrated by DLS and NMR experiments.

A Self-locked ß-Cyclodextrin-rhodamine B Spirolactam with Photoswitching Properties.

Supramolecular organization and self-assembly are the pillars of functionality of many nanosystems. The covalent conjugate (6-spirolactam rhodamine B-6-monodeoxy)-ß-cyclodextrin (Rho-ßCD) is assembled as a self-included, rigid nanostructure, identical in the crystal and in aqueous solution, as revealed by detailed X-ray and NMR analyses. Rho-ßCD self-assembly is the result of an interesting reaction pathway, which partially de-aggregates Rho and disturbs the zwitterion↔spirolactone equilibrium. Rho-ßCD is stable at pH 4.6, but displays controllable photoswitching between the colored, fluorescent, zwitterionic and the colorless, non-fluorescent closed structures, during several iterative cycles. After an initial drop in absorbance, the on-off process continues without further changes under our irradiation conditions, a consequence of the specific self-locked arrangement of Rho in the cavity. Rho-ßCD exemplifies a water soluble photoresponsive nanosystem with improved photostability suggesting promising applications in super resolution bioimaging.

Host-guest inclusion complexes of hydroxytyrosol with cyclodextrins: Development of a potential functional ingredient for food application.

Hydroxytyrosol (HT), a potent phenolic phytochemical, exerts positive health effects due to its antioxidant properties. However, it is highly reactive to oxygen, light, and heat and presents high instability. Alpha- and beta-cyclodextrin (α-CD, ß-CD) have structures that allow them to encapsulate a variety of hydrophobic molecules. The aim of this study was to examine the outcomes of the inclusion of HT into α-CD and ß-CD. Aqueous solutions of HT and either α-CD or ß-CD were prepared and freeze-drying was applied for the encapsulation, in 1:1 and 2:1 molar ratios. The produced solid complexes were studied and characterized using NMR spectroscopy, differential scanning calorimetry (DSC) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Encapsulation efficiency (EE%), stability, and in vitro release of the encapsulated complexes under simulated digestion conditions were also evaluated. In both DSC thermograms and FTIR spectra of the inclusion complexes, absence of the characteristic peaks of HT and shifts of the CDs peaks were observed, showing an interaction between the molecules. NMR suggested a stronger complex formed between ß-CD and HT. The EE% of ß-CD/HT (1:1 and 2:1) complexes and α-CD/HT (1:1) complex was found to be higher (83%, 76%, 78%, respectively), compared to α-CD/HT (2:1) (51%). Data obtained support the encapsulation of HT in both CDs, revealing a potential interaction between them and an improvement in HT's thermal stability. Regarding the in vitro release study, both CD complexes had similar behavior and a controlled release of HT in the intestinal site was observed. PRACTICAL APPLICATION: The encapsulation of hydroxytyrosol in cyclodextrins resulted in white amorphous food-grade powders with no aroma and taste. Incorporation of these powders in foods could lead to an increase in their antioxidant content and offer an additional nutritional value.

5-ALA Is a Potent Lactate Dehydrogenase Inhibitor but Not a Substrate: Implications for Cell Glycolysis and New Avenues in 5-ALA-Mediated Anticancer Action.

In a course of metabolic experiments, we determined that the addition of δ-aminolevulinic acid (5-ALA) to a panel of glioblastoma multiforme (GBM) cells caused a steep reduction in their glycolytic activity. This reduction was accompanied by a decrease in adenosine triphosphate (ATP) production from glycolysis. These results suggested that 5-ALA is an inhibitor of glycolysis; due to the structural similarity of 5-ALA to the established lactate dehydrogenase (LDH) inhibitors oxamate (OXM) and tartronate (TART), we initially investigated LDH inhibition by 5-ALA in silico. The modelling revealed that 5-ALA could indeed be a competitive inhibitor of LDH but not a substrate. These theoretical findings were corroborated by enzymatic and cell lysate assays in which 5-ALA was found to confer a potent LDH inhibition comparable to that of OXM and TART. We subsequently evaluated the effect of 5-ALA-induced glycolysis inhibition on the viability of GBM cells with diverse metabolic phenotypes. In the Warburg-type cell lines Ln18 and U87, incubation with 5-ALA elicited profound and irreversible cell death (90-98%) at 10 mM after merely 24 h. In T98G, however, which exhibited both high respiratory and glycolytic rates, LD95 was achieved after 72 h of incubation with 20 mM 5-ALA. We additionally examined the production of the 5-ALA photosensitive metadrug protoporphyrin IX (PpIX), with and without prior LDH inhibition by TART. These studies revealed that ~20% of the 5-ALA taken up by the cells was engaged in LDH inhibition. We subsequently performed 5-ALA photodynamic therapy (PDT) on Ln18 GBM cells, again with and without prior LDH inhibition with TART, and found a PDT outcome enhancement of ~15% upon LDH pre-inhibition. We expect our findings to have a profound impact on contemporary oncology, particularly for the treatment of otherwise incurable brain cancers such as GBM, where the specific accumulation of 5-ALA is very high compared to the surrounding normal tissue.

Unsymmetrical, monocarboxyalkyl meso-arylporphyrins in the photokilling of breast cancer cells using permethyl-ß-cyclodextrin as sequestrant and cell uptake modulator.

In the search for photosensitizers with chemical handles to facilitate their integration into complex drug delivery nanosystems, new, unsymmetrically substituted, water insoluble meso-tetraphenylporphyrin and meso-tetra(m-hydroxyphenyl)porphyrin derivatives bearing one carboxyalkyl side chain were synthesized. Permethyl-ß-cyclodextrin (pMßCD) was their ideal monomerizing host and highly efficient shuttle to transfer them into water. New assembly modes of the extremely stable (Kbinding > 1012 M-2) 2:1 complexes were identified. The complexes are photostable and do not disassemble in FBS-containing cell culture media for 24 h. Incubation of breast cancer MCF-7 cells with the complexes results in intense intracellular fluorescence, strongly enhanced in the endoplasmic reticulum (ER), high photokilling efficiency (~90%) and low dark toxicity. pMßCD stands out as a very capable molecular isolator of mono-carboxyalkyl-arylporphyrins that increases uptake and modulates their localization in the cells. The most efficient porphyrins are envisaged as suitable photosensitizers that can be linked to biocompatible drug carriers for photo- and chemo-therapy applications.

Design and Synthesis of Porphyrin-Nitrilotriacetic Acid Dyads with Potential Applications in Peptide Labeling through Metallochelate Coupling.

The need to detect and monitor biomolecules, especially within cells, has led to the emerging growth of fluorescent probes. One of the most commonly used labeling techniques for this purpose is reversible metallochelate coupling via a nitrilotriacetic acid (NTA) moiety. In this study, we focus on the synthesis and characterization of three new porphyrin-NTA dyads, TPP-Lys-NTA, TPP-CC-Lys-NTA, and Py 3 P-Lys-NTA composed of a porphyrin derivative covalently connected with a modified nitrilotriacetic acid chelate ligand (NTA), for possible metallochelate coupling with Ni2+ ions and histidine sequences. Emission spectroscopy studies revealed that all of the probes are able to coordinate with Ni2+ ions and consequently can be applied as fluorophores in protein/peptide labeling applications. Using two different histidine-containing peptides as His6-tag mimic, we demonstrated that the porphyrin-NTA hybrids are able to coordinate efficiently with the peptides through the metallochelate coupling process. Moving one step forward, we examined the ability of these porphyrin-peptide complexes to penetrate and accumulate in cancer cells, exploring the potential utilization of our system as anticancer agents.

Symmetry requirements for effective blocking of pore-forming toxins: comparative study with alpha-, beta-, and gamma-cyclodextrin derivatives.

We compared the abilities of structurally related cationic cyclodextrins to inhibit Bacillus anthracis lethal toxin and Staphylococcus aureus α-hemolysin. We found that both ß- and γ-cyclodextrin derivatives effectively inhibited anthrax toxin action by blocking the transmembrane oligomeric pores formed by the protective antigen (PA) subunit of the toxin, whereas α-cyclodextrins were ineffective. In contrast, α-hemolysin was selectively blocked only by ß-cyclodextrin derivatives, demonstrating that both symmetry and size of the inhibitor and the pore are important.

Helical Nanofibers Formed by Palladium-Mediated Assembly of Organic Homochiral Macrocycles Containing Binaphthyl and Pyridyl Units.

Herein, we report the synthesis and characterization of homochiral macrocycles, in which molecular rigidity, combined with the presence of multiple functional groups, allow for the assembly of helical nanostructures. 1,1'-bi-2-naphthol (Binol) units are used as robust chirality inducers, and pyridyl units embedded within the molecular frameworks allow the assembly, upon coordination with Pd(II) metal ions, of the macrocyclic building blocks. CD and NMR spectroscopies show the formation of ordered 1D assembly in solution. AFM studies indicate that the molecular systems are capable of forming nanoscale structures. The effective transfer of chiral information results in helical nanofibers, with lengths ranging from a few hundreds of nanometers to some micrometers. AFM line profiles reveal a helical longitudinal period of about 50 nm and a transverse width of 25 to 45 nm after deconvolution.

Novel polycarboxylated EDTA-type cyclodextrins as ligands for lanthanide binding: study of their luminescence, relaxivity properties of Gd(iii) complexes, and PM3 theoretical calculations.

Novel -type cyclodextrin (CD) derivatives, , and , bearing 6, 7 and 8 bis(carboxymethyl)amino (iminodiacetic acid) groups, respectively, were prepared, and their complexation with Eu(iii), Tb(iii) and Gd(iii) ions was studied. Luminescence titrations and mass spectrometry showed formation of multimetal complexes ( 2 to 3, mainly 3 and exactly 4 metal ions), whereas luminescence lifetime measurements revealed the presence of exchangeable water molecules. Semiempirical quantum mechanical calculations, performed by the PM3 method and assessed by DFT calculations on model ligands, indicated efficient multi-metal complexation, in agreement with the experiment. The structures showed coordination of the metal ions in the outer primary side of the CDs via 4 carboxylate O atoms, 2 N atoms and a glucopyranose O atom per metal ion. Coordination of water molecules was also predicted, in accordance with experimental results. Calculated bond lengths and angles were in agreement with literature experimental values of lanthanide complexes. Calculated energies showed that complex stability decreases in the order > > . (1)H NMR molecular relaxivity measurements for the Gd(iii) complexes of , or in water afforded values 4 to 10 times higher than the relaxivity of a commercial contrast agent at 12 MHz, and 6 to 20 times higher at 100 MHz. Solutions of and Gd(iii) complexes in human blood plasma displayed relaxivity values at 100 MHz 7 and 12 times, respectively, higher than the commercial agent. MTT tests of the Gd(iii) complexes using human skin fibroblasts did not show toxicity. Attempts to supramolecularly sensitize the luminescence of the lanthanide complexes using various aromatic CD guests were ineffective, evidently due to large guest-metal distances and inefficient inclusion. The described lanthanide complexes, could be useful as contrast agents in MRI.

Porphyrinoid-Cyclodextrin Assemblies in Biomedical Research: An Update.

Porphyrinoids, well-known cofactors in fundamental processes of life, have stimulated interest as synthetic models of natural systems and integral components of photodynamic therapy, but their utilization is compromised by self-aggregation in aqueous media. The capacity of cyclodextrins to include hydrophobic molecules in their cavity provides porphyrinoids with a protective environment against oxidation and the ability to disperse efficiently in biological fluids. Moreover, engineered cyclodextrin-porphyrinoid assemblies enhance the photodynamic abilities of porphyrinoids, can carry chemotherapeutics for synergistic modalities, and can be enriched with functions including cell recognition, tissue penetration, and imaging. This Perspective includes synthetic porphyrinoid-cyclodextrin models of proteins participating in fundamental processes, such as enzymatic catalysis, respiration, and electron transfer. In addition, since porphyrinoid-cyclodextrin systems comprise third generation photosensitizers, recent developments for their utilization in photomedicine, that is, multimodal therapy for cancer (e.g., PDT, PTT) and antimicrobial treatment, and eventually in biocompatible therapeutic or diagnostic platforms for next-generation nanomedicine and theranostics are discussed.

Increased antibiotic efficacy and noninvasive monitoring of Staphylococcus epidermidis biofilms using per-cysteamine-substituted γ-cyclodextrin - A delivery effect validated by fluorescence microscopy.

Limited and poor delivery of antibiotics is cited as one reason for the difficulty in treating antibiotic-resistant biofilms associated with chronic infections. We investigate the effectiveness of a positively charged, single isomer cyclodextrin derivative, octakis[6-(2-aminoethylthio)-6-deoxy]-γ-CD (γCys) to improve the delivery of antibiotics to biofilms. Using multiphoton laser scanning microscopy complemented with super-resolution fluorescence microscopy, we showed that γCys tagged with fluorescein (FITC) is uniformly distributed throughout live S. epidermidis biofilm cultures in vitro and results suggest it is localized extracellularly in the biofilm matrix. NMR spectroscopic data in aqueous solution confirm that γCys forms inclusion complexes with both the antibiotics oxacillin and rifampicin. Efficacy of γCys/antibiotic (oxacillin and rifampicin) was measured in the biofilms. While treatment with γCys/oxacillin had little improvement over oxacillin alone, γCys/rifampicin reduced the biofilm viability to background levels demonstrating a remarkable improvement over rifampicin alone. The strong synergistic effect for γCys/rifampicin is at this stage not clearly understood, but plausible explanations are related to increased solubility of rifampicin upon complexation and/or synergistic interference with components of the biofilm. The results demonstrate that designed cyclodextrin nanocarriers, like γCys, efficiently deliver suitable antibiotics to biofilms and that fluorescence microscopy offers a novel approach for mechanistic investigations.

Suppressing the Photocatalytic Activity of Zinc Oxide Electron-Transport Layer in Nonfullerene Organic Solar Cells with a Pyrene-Bodipy Interlayer.

Organic solar cells based on nonfullerene acceptors have recently witnessed a significant rise in their power conversion efficiency values. However, they still suffer from severe instability issues, especially in an inverted device architecture based on the zinc oxide bottom electron transport layers. In this work, we insert a pyrene-bodipy donor-acceptor dye as a thin interlayer at the photoactive layer/zinc oxide interface to suppress the degradation reaction of the nonfullerene acceptor caused by the photocatalytic activity of zinc oxide. In particular, the pyrene-bodipy-based interlayer inhibits the direct contact between the nonfullerene acceptor and zinc oxide hence preventing the decomposition of the former by zinc oxide under illumination with UV light. As a result, the device photostability was significantly improved. The π-π interaction between the nonfullerene acceptor and the bodipy part of the interlayer facilitates charge transfer from the nonfullerene acceptor toward pyrene, which is followed by intramolecular charge transfer to bodipy part and then to zinc oxide. The bodipy-pyrene modified zinc oxide also increased the degree of crystallization of the photoactive blend and the face-on stacking of the polymer donor molecules within the blend hence contributing to both enhanced charge transport and increased absorption of the incident light. Furthermore, it decreased the surface work function as well as surface energy of the zinc oxide film all impacting in improved power conversion efficiency values of the fabricated cells with champion devices reaching values up to 9.86 and 11.80% for the fullerene and nonfullerene-based devices, respectively.