The E3 ligase adapter cereblon targets the C-terminal cyclic imide degron.

The ubiquitin E3 ligase substrate adapter cereblon (CRBN) is a target of thalidomide and lenalidomide1, therapeutic agents used in the treatment of haematopoietic malignancies2-4 and as ligands for targeted protein degradation5-7. These agents are proposed to mimic a naturally occurring degron; however, the structural motif recognized by the thalidomide-binding domain of CRBN remains unknown. Here we report that C-terminal cyclic imides, post-translational modifications that arise from intramolecular cyclization of glutamine or asparagine residues, are physiological degrons on substrates for CRBN. Dipeptides bearing the C-terminal cyclic imide degron substitute for thalidomide when embedded within bifunctional chemical degraders. Addition of the degron to the C terminus of proteins induces CRBN-dependent ubiquitination and degradation in vitro and in cells. C-terminal cyclic imides form adventitiously on physiologically relevant timescales throughout the human proteome to afford a degron that is endogenously recognized and removed by CRBN. The discovery of the C-terminal cyclic imide degron defines a regulatory process that may affect the physiological function and therapeutic engagement of CRBN.

Lung-Targeting Perylenediimide Nanocomposites for Efficient Therapy of Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis, an idiopathic interstitial lung disease with high mortality, remains challenging to treat due to the lack of clinically approved lung-targeting drugs. Herein, we present PDIC-DPC, a perylenediimide derivative that exhibits superior lung-selective enrichment. PDIC-DPC forms nanocomposites with plasma proteins, including fibrinogen beta chain and vitronectin, which bind to pulmonary endothelial receptors for lung-specific accumulation. Moreover, PDIC-DPC significantly suppresses transforming growth factor beta1 and activates adenosine monophosphate-activated protein kinase. As a result, compared to existing therapeutic drugs, PDIC-DPC achieves superior therapeutic outcomes, evidenced by the lowest Ashcroft score, significantly improved pulmonary function, and an extended survival rate in a bleomycin-induced pulmonary fibrosis model. This study elucidates the lung-selective enrichment of assembled prodrug from biological perspectives and affords a platform enabling therapeutic efficiency on idiopathic pulmonary fibrosis.

Enzymatic Reaction-Coupled, Cooperative Supramolecular Polymerization.

Nature employs sophisticated mechanisms to precisely regulate self-assembly and functions within biological systems, exemplified by the formation of cytoskeletal filaments. Various enzymatic reactions and auxiliary proteins couple with the self-assembly process, meticulously regulating the length and functions of resulting macromolecular structures. In this context, we present a bioinspired, reaction-coupled approach for the controlled supramolecular polymerization in synthetic systems. To achieve this, we employ an enzymatic reaction that interfaces with the adenosine triphosphate (ATP)-templated supramolecular polymerization of naphthalene diimide monomers (NSG). Notably, the enzymatic production of ATP (template) plays a pivotal role in facilitating reaction-controlled, cooperative growth of the NSG monomers. This growth process, in turn, provides positive feedback to the enzymatic production of ATP, creating an ideal reaction-coupled assembly process. The success of this approach is further evident in the living-growth characteristic observed during seeding experiments, marking this method as the pioneering instance where reaction-coupled self-assembly precisely controls the growth kinetics and structural aspects of supramolecular polymers in a predictive manner, akin to biological systems.

Potential-Resolved Ratio Electrochemiluminescence Biosensor Based on Perylene Diimide-MOF and DNA Nanoflowers-CdS Quantum Dots for Detection of Dual Targets.

BRCA1 gene and carcinoembryonic antigen (CEA) are important markers of breast cancer, so accurate detection of them is significant for early detection and diagnosis of breast cancer. In this study, a potential-resolved ratio electrochemiluminescence (ECL) biosensor using perylene diimide (PDI)-metal-organic framework and DNA nanoflowers (NFs)-CdS quantum dots (QDs) was constructed for detection of BRCA1 and CEA. Specifically, PDI-MOF and CdS QDs can generate potential-resolved intense ECL signals only using one coreactant, so the detection procedure can be effectively simplified. PDI-MOF was first attached to the electrode by graphene oxide, and the dopamine (DA) probe was linked to quench the ECL signal by DNA hybridization. In the presence of target BRCA1, it can form a bipedal DNA walker, so the quenching molecules (DA) were detached from the electrode via the walker amplification process aided by Mg2+, so that the PDI signal at -0.25 V was restored for the BRCA1 assay. Moreover, CdS QDs@DNA NFs as amplified signal probes were formed by self-assembly, and the target CEA-amplified product introduced the CdS QDs@DNA NFs to the electrode, so the QD ECL signal at -1.42 V was enhanced, while the ECL signal of PDI is unchanged; thus, CEA detection was achieved by the ratio value between them. Therefore, the detection accuracy is guaranteed by detection of two cancer markers and a ratio value. This biosensor has a great contribution to the development of new ECL materials and a novel ECL technique for fast and efficient multitarget assays, showing great significance for the early monitoring and diagnosis of breast cancer.

A Self-Assembly-Induced Exciton Delocalization Strategy for Converting a Perylene Diimide Derivative from a Type-II to Type-I Photosensitizer.

Type-I photosensitizers have shown advantages in addressing the shortcomings of traditional oxygen-dependent type-II photosensitizers for the photodynamic therapy (PDT) of hypoxic tumors. However, developing type-I photosensitizers is yet a huge challenge because the type-II energy transfer process is much faster than the type-I electron transfer process. Herein, from the fundamental point of view, an effective approach is proposed to improve the electron transfer efficiency of the photosensitizer by lowering the internal reorganization energy and exciton binding energy via self-assembly-induced exciton delocalization. An example proof is presented by the design of a perylene diimide (PDI)-based photosensitizer (PDIMp) that can generate singlet oxygen (1O2) via a type-II energy transfer process in the monomeric state, but induce the generation of superoxide anion (O2˙-) via a type-I electron transfer process in the aggregated state. Significantly, with the addition ofcucurbit[6]uril (CB[6]), the self-assembled PDIMp can convert back to the monomeric state via host-guest complexation and consequently recover the generation of 1O2. The biological evaluations reveal that supramolecular nanoparticles (PDIMp-NPs) derived from PDIMp show superior phototherapeutic performance via synergistic type-I PDT and mild photothermal therapy (PTT) against cancer under either normoxia or hypoxia conditions.

Fast and Efficient Sensing of Drugs in Water Using Self-Assembling D-Glucamine-Functionalized Naphthalenediimide and 1,8-Naphthalimide Fluorophores.

Fast and sensitive quantification of drugs as emerging pollutants in water bodies is a pressing need in contemporary society, to prevent serious environmental concerns that could negatively impact on human health. This explains the surge of interest in this field, and the need to identify highly selective sensing systems. Addressing this issue, in this work we synthesized two D-glucamine functionalized fluorophores bearing self-assembling cores, as 1,8-naphthalimide and naphthalene diimide. We studied their self-assembly in water solution, and characterized the aggregated formed by determining their stability constant, their morphology and size by scanning electron microscopy, resonance light scattering and dynamic light scattering, as well their solid-state emission ability. Then, we studied their sensing ability, in water, towards pharmaceutically active compounds such as ciprofloxacin, nalidixic acid, carbamazepine and diclofenac sodium salt, by fluorescence investigation. Data collected show that the self-assembling ability is significantly affected by the fluorophore structure, which in turn also determines sensing ability. In particular, the naphtalene diimide-based probe was the most sensitive, with LOD as low as 0.01 µM in the presence of nalidixic acid, which is in line and competitive with more complex sensing systems, recently reported in the literature.

Carbohydrate-Functionalized Anthracene Carboximides as Multivalent Ligands and Bio-Imaging Agents.

Anthracene carboximides (ACIs) conjugated with gluco-, galacto- and mannopyranosides are synthesized, by glycosylation of N-hydroxyethylanthracene carboximide acceptor with glycosyl donors. Glycoconjugation of anthracene carboximide increases the aq. solubility by more than 3-fold. The glycoconjugates display red-shifted absorption and emission, as compared to anthracene. Large Stokes shift (λabs/λem=445/525 nm) and high fluorescence quantum yields (Φ) of 0.86 and 0.5 occur in THF and water, respectively. The ACI-glycosides undergo facile photodimerization in aqueous solutions, leading to the formation of the head-to-tail dimer, as a mixture of syn and anti-isomers. Solution phase and solid-state characterizations by dynamic light scattering (DLS), microscopic imaging by atomic force (AFM) and transmission electron (TEM) microscopies reveal self-assembled vesicle structures of ACI glycosides. These self-assembled structures act as multivalent glycoclusters for ligand-specific lectin binding, as evidenced by the binding of Man-ACI to Con A, by fluorescence and turbidity assays. The conjugates do not show cellular cytotoxicity (IC50) till concentrations of 50 µM with HeLa and HepG2 cell lines and are cell-permeable, showing strong fluorescence inside the cells. These properties enable the glycoconjugates to be used in cell imaging. The non-selective cellular uptake of the glycoconjugates suggests a passive diffusion through the membrane.

Hydrogen-Bonding-Regulated Morphology Control and the Impact on the Antibacterial Activity of Cationic π-Amphiphiles.

This manuscript describes the synthesis, self-assembly, and antibacterial properties of naphthalene-diimide (NDI)-derived cationic π-amphiphiles. Three such asymmetric NDI derivatives with a nonionic hydrophilic wedge and a guanidine group in the two opposite sides of the NDI chromophore were considered. They differ by a single functional group (hydrazide, amide, and ester for NDI-1, NDI-2, and NDI-3, respectively), located in the linker between the NDI and the hydrophilic wedge. For NDI-1, the H-bonding among the hydrazides regulated unilateral stacking and a preferential direction of curvature of the resulting supramolecular polymer, producing an unsymmetric polymersome with the guanidinium groups displayed at the outer surface. NDI-3, lacking any H-bonding group, exhibits π-stacking without any preferential orientation and generates spherical particles with a relatively poor display of the guanidium groups. In sharp contrast to NDI-1, NDI-2 exhibits an entangled one-dimensional (1D) fibrillar morphology, indicating the prominent role of the H-bonding motif of the amide group and flexibility of the linker. The antibacterial activity of these assemblies was probed against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). NDI-1 showed the most promising antibacterial activity with a minimum inhibitory concentration (MIC) of ∼7.8 µg/mL against S. aureus and moderate activity (MIC ∼ 125 µg/mL) against E. coli. In sharp contrast, NDI-3 did not show any significant activity against the bacteria, suggesting a strong impact of the H-bonding-regulated directional assembly. NDI-2, forming a fibrillar network, showed moderate activity against S. aureus and negligible activity against E. coli, highlighting a significant impact of the morphology. All of these three molecules were found to be compatible with mammalian cells from the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and hemolysis assay. The mechanistic investigation by membrane polarization assay, live/dead fluorescence assay, and microscopy studies confirmed the membrane disruption mechanism of cell killing for the lead candidate NDI-1.

A perylene diimide electrochemical probe with persulfate as a signal enhancer for dopamine sensing.

Dopamine (DA) is an important biomarker related to parkinsonism, schizophrenia and renal disease. Traditional electrochemical sensors for DA were based on the direct electrochemical oxidation of DA. In this paper, we report a new sensing strategy using N,N'-di(trimethylaminoethyl)perylene diimide (TMPDI) as an electrochemical probe and K2S2O8 as a signal enhancer for DA detection between 0 and -0.7 V with the DPV technique. MoS2 nanoflowers prepared by the hydrothermal method were used as a nanocarrier to load TMPDI. The reduction current of TMPDI was found to show a stepwise and significant increase at -0.24 V with the increase of concentration of K2S2O8 due to the continuous cycle of TMPDI molecules' electrochemical reduction and chemical oxidation. The presence of DA caused a large decrease of the reduction current of TMPDI due to the synergistic interaction of the competitive consumption of DA for K2S2O8 and the blocking effect of polyDA adhering to the electrode surface. The decreased current exhibited a linear response for DA from 10 pM to 100 µM with a detection limit of 4.1 pM and the proposed sensor showed high selectivity and excellent feasibility in human urine/serum sample detection.

Design and synthesis of dual functional NBD-fluorophore-incorporated naphthalene diimide derivatives as G-quadruplex ligands.

Nitrobenzoxadiazole (NBD)-incorporated naphthalene diimide derivatives were designed and synthesized as candidates of antitumor agents with cytotoxicity against human pancreatic cancer cell MIA PaCa-2. Among these, compounds 1NND and 3NND exhibited fluorescent "turn-off" property toward human telomeric G-quadruplex (G4), which allows the direct measurement of dissociation constant (Kd) of ligands against G4 by fluorescence titration method. Notably, the compound 1NND not only exhibited great cytotoxic activity against MIA PaCa-2 with a half maximal inhibitory concentration (IC50) of 77.9 nM, but also exhibited high affinity against G4 with Kd of 1.72 µM. Furthermore, the target binding properties were investigated by circular dichroism (CD) spectra and further studied by molecular docking methods.

Thermally Stable and Transparent Polyimide Derived from Side-Group-Regulated Spirobifluorene Unit for Substrate Application.

Advancements in flexible electronic technology, especially the progress in foldable displays and under-display cameras (UDC), have created an urgent demand for high-performance colorless polyimide (CPI). However, current CPIs lack sufficient heat resistance for substrate applications. In this work, four kinds of rigid spirobifluorene diamines are designed, and the corresponding polyimides are prepared by their condensation with 5,5'-(perfluoropropane-2,2-diyl) bis(isobenzofuran-1,3-dione) (6FDA) or 9,9-bis(3,4-dicarboxyphenyl) fluorene dianhydride (BPAF). The rigid and conjugated spirobifluorene units endow the polyimides with higher glass transition temperature (Tg) ranging from 356 to 468 °C. Their optical properties are regulated by small side groups and spirobifluorene structure with a periodically twisted molecular conformation. Consequently, a series of CPIs with an average transmittance ranging from 75% to 88% and a yellowness index (YI) as low as 2.48 are obtained. Among these, 27SPFTFA-BPAF presents excellent comprehensive performance, with a Tg of 422 °C, a 5 wt.% loss temperature (Td5) of 562 °C, a YI of 3.53, and a tensile strength (δmax) of 140 MPa, respectively. The mechanism underlying the structure-property relationship is investigated by experimental comparison and theoretical calculation, and the proposed method provides a pathway for designing highly rigid conjugated CPIs with excellent thermal stability and transparency for photoelectric engineering.

Constructing Novel High Dielectric Constant Polyimides Containing Dipolar Pendant Groups with Enhanced Orientational Polarization.

Polymer dielectrics with high dielectric constant are urgently demanded for potential electrical and pulsed power applications. The design of polymers with side chains containing dipolar groups is considered an effective method for preparing materials with a high dielectric constant and low loss. This study synthesizes and comprehensively compare the dielectric properties of novel polyimides with side chains containing urea (BU-PI), carbamate (BC-PI), and sulfonyl (BS-PI) functional groups. The novel polyimides exhibit relatively high dielectric constant and low dielectric loss values due to the enhanced orientational polarization and suppressed dipole-dipole interactions of dipolar groups. In particular, BU-PI containing urea pendant groups presents the highest dielectric constant of 6.14 and reasonably low dielectric loss value of 0.0097. The strong γ transitions with low activation energies derived from dielectric spectroscopy measurements have been further evaluated to demonstrate the enhanced free rotational motion of urea pendant dipoles. In energy storage applications, BU-PI achieves a discharged energy density of 6.92 J cm-3 and a charge-discharge efficiency above 83% at 500 MV m-1. This study demonstrates that urea group, as dipolar pendant group, can provide polymers with better dielectric properties than the most commonly used sulfonyl groups.

Ionic Thermoelectric Generators in Vertical and Planar Topologies Based on Fluorinated Polymer Hybrid Materials with Ionic Liquids.

Ionic thermoelectrics (TEs), in which voltage generation is based on ion migration, are suitable for applications based on their low cost, high flexibility, high ionic conductivity, and wide range of Seebeck coefficients. This work reports on the development of ionic TE materials based on the poly(vinylidene fluoride-trifluoroethylene), Poly(VDF-co-TrFE), as host polymer blended with different contents of the ionic liquid, IL, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI]. The morphology, physico-chemical, thermal, mechanical, and electrical properties of the samples are evaluated together with the TE response. It is demonstrated that the IL acts as a nucleating agent for polymer crystallization. The mechanical properties and ionic conductivity values are dependent on the IL content. A high room temperature ionic conductivity of 0.008 S cm-1 is obtained for the sample with 60 wt% of [EMIM][TFSI] IL. The TE properties depend on both IL content and device topology-vertical or planar-the largest generated voltage range being obtained for the planar topology and the sample with 10 wt% of IL content, characterized by a Seebeck coefficient of 1.2 mV K-1. Based on the obtained maximum power density of 4.9 µW m-2, these materials are suitable for a new generation of TE devices.

Is a Vitrimer with a High Glass Transition Temperature Available? A Case Study on Rigid Polyimides Cross-Linked with Dynamic Ester Bonds.

Vitrimers, possessing associative covalent adaptable networks, are cross-linked polymers exhibiting malleable (glass-like) feature and recyclable and reprocessable (thermoplastics-like) properties. The dynamic behaviors of vitrimer are dependent on both chain/molecular mobility (glass transition temperature, Tg) and dynamic bond-exchanging reaction rate (topology freezing transition temperature, Tv). This work aims on probing the effect of high Tg on the stress relaxation and physical recyclability of vitrimers, employing a polyimide cross-linked with dynamic ester bonds (Tg: 310 °C) as the example. Due to its high Tg and chain rigidity, the cross-linked polyimide does not exhibit a high extent of stress relaxation behavior at 320 °C (10 °C above its Tg), even though the temperature is much higher than the hypothetical Tv. While raising the processing temperature to 345 °C, the cross-linked polyimide exhibits a stress relaxation time of about 3300 s and physical malleability. Nevertheless, side reactions may occur in the recycling and reprocessing process under the harsh condition (high temperature and high pressure) to alter the thermal properties of the recycled sample. The diffusion control plays a critical role on the topography transition of a vitrimer having a high Tg. The Tg ceiling is noticeable for developments of vitrimers.

Role of intramolecular hydrogen bonds in promoting electron flow through amino acid and oligopeptide conjugates.

Elucidating the factors that control charge transfer rates in relatively flexible conjugates is of importance for understanding energy flows in biology as well as assisting the design and construction of electronic devices. Here, we report ultrafast electron transfer (ET) and hole transfer (HT) between a corrole (Cor) donor linked to a perylene-diimide (PDI) acceptor by a tetrameric alanine (Ala)4 Selective photoexcitation of the donor and acceptor triggers subpicosecond and picosecond ET and HT. Replacement of the (Ala)4 linker with either a single alanine or phenylalanine does not substantially affect the ET and HT kinetics. We infer that electronic coupling in these reactions is not mediated by tetrapeptide backbone nor by direct donor-acceptor interactions. Employing a combination of NMR, circular dichroism, and computational studies, we show that intramolecular hydrogen bonding brings the donor and the acceptor into proximity in a "scorpion-shaped" molecular architecture, thereby accounting for the unusually high ET and HT rates. Photoinduced charge transfer relies on a (Cor)NH…O=C-NH…O=C(PDI) electronic-coupling pathway involving two pivotal hydrogen bonds and a central amide group as a mediator. Our work provides guidelines for construction of effective donor-acceptor assemblies linked by long flexible bridges as well as insights into structural motifs for mediating ET and HT in proteins.

Diesters of monoimide of perylene-3,4,9,10-tetracarboxylic acid - Synthesis, characterization, and application for dyeing polyester fibre, polystyrene, and poly (methyl methacrylate) films.

Three dyes-diesters of monoimides of perylene-3,4,9,10-tetracarboxylic acid were synthesized in three-stage process: esterification, hydrolysis, and monoimidation as potential fluorescent light-stable colorants for high visibility safety wear. The structure of these compounds was confirmed by 1H nuclear magnetic resonance spectroscopy and mass spectrometry, and their spectroscopic and physicochemical properties were determined. Colorants were applied to dyeing polyester fibre and polystyrene and poly (methyl methacrylate) films. The light, wash, and rubbing fastness of the dyeings were determined, and chromaticity coordinates were measured and discussed.

Dual-mode electrochemical and electrochemiluminescence detection of dopamine based on perylene diimide self-assembly material.

The self-assembly material N,N-bis-(3-dimethyl aminopropyl)-3,4,9,10-perylene tetracarboxylic acid diimide (PDI) is reported to show electrochemical (EC)/electrochemiluminescence (ECL) property for designing new dual-mode dopamine (DA) sensors. K2S2O8 significantly improved the EC reduction current at -0.346 V and ECL intensity at -0.25 V of the PDI self-assembly material. DA largely decreased the EC reduction current and ECL intensity of this homogeneous EC/ECL material due to the competitive consumption of K2S2O8 in the oxidization process of DA and the low electron conductivity of polyDA formed through the oxidization of DA by K2S2O8. In addition, the ECL quenching mechanism involved an energy-transfer process resulting from the collision between the produced o-benzoquinone species (oxidization of DA) and the excited state of PDI, which decreased the ECL intensity. This homogeneous EC/ECL material showed linear EC current response for DA from 5.0 nM to 50.0 µM with a detection of limit of 2.7 nM and linear ECL response for DA from 1.0 nM to 100.0 µM with a detection of limit of 0.41 nM. The proposed dual-mode EC/ECL sensors also showed good feasibility in urine sample analysis.

Soluble Fluorinated Cardo Copolyimide as an Effective Additive to Photopolymerizable Compositions Based on Di(meth)acrylates: Application for Highly Thermostable Primary Protective Coating of Silica Optical Fiber.

The development of photocurable compositions is in high demand for the manufacture of functional materials for electronics, optics, medicine, energy, etc. The properties of the final photo-cured material are primarily determined by the initial mixture, which needs to be tuned for each application. In this study we propose to use simple systems based on di(meth)acrylate, polyimide and photoinitiator for the preparation of new photo-curable compositions. It was established that a fluorinated cardo copolyimide (FCPI) based on 2,2-bis-(3,4-dicarboxydiphenyl)hexafluoropropane dianhydride, 9,9-bis-(4-aminophenyl)fluorene and 2,2-bis-(4-aminophenyl)hexafluoropropane (1.00:0.75:0.25 mol) has excellent solubility in di(met)acrylates. This made it possible to prepare solutions of FCPI in such monomers, to study the effect of FCPI on the kinetics of their photopolymerization in situ and the properties of the resulting polymers. According to the obtained data, the solutions of FCPI (23 wt.%) in 1,4-butanediol diacrylate (BDDA) and FCPI (15 wt.%) in tetraethylene glycol diacrylate were tested for the formation of the primary protective coatings of the silica optical fibers. It was found that the new coating of poly(BDDA-FCPI23%) can withstand prolonged annealing at 200 °C (72 h), which is comparable or superior to the known most thermally stable photo-curable coatings. The proposed approach can be applied to obtain other functional materials.

amer1 Regulates Zebrafish Craniofacial Development by Interacting with the Wnt/ß-Catenin Pathway.

Microtia-atresia is a rare type of congenital craniofacial malformation causing severe damage to the appearance and hearing ability of affected individuals. The genetic factors associated with microtia-atresia have not yet been determined. The AMER1 gene has been identified as potentially pathogenic for microtia-atresia in two twin families. An amer1 mosaic knockdown zebrafish model was constructed using CRISPR/Cas9. The phenotype and the development process of cranial neural crest cells of the knockdown zebrafish were examined. Components of the Wnt/ß-catenin pathway were examined by qPCR, Western blotting, and immunofluorescence assay. IWR-1-endo, a reversible inhibitor of the Wnt/ß-catenin pathway, was applied to rescue the abnormal phenotype. The present study showed that the development of mandibular cartilage in zebrafish was severely compromised by amer1 knockdown using CRISPR/Cas9. Specifically, amer1 knockdown was found to affect the proliferation and apoptosis of cranial neural crest cells, as well as their differentiation to chondrocytes. Mechanistically, amer1 exerted an antagonistic effect on the Wnt/ß-catenin pathway. The application of IWR-1-endo could partially rescue the abnormal phenotype. We demonstrated that amer1 was essential for the craniofacial development of zebrafish by interacting with the Wnt/ß-catenin pathway. These findings provide important insight into the role of amer1 in zebrafish mandibular development and the pathology of microtia-atresia caused by AMER1 gene mutations in humans.

A Phenotypic Approach to the Discovery of Potent G-Quadruplex Targeted Drugs.

G-quadruplex (G4) sequences, which can fold into higher-order G4 structures, are abundant in the human genome and are over-represented in the promoter regions of many genes involved in human cancer initiation, progression, and metastasis. They are plausible targets for G4-binding small molecules, which would, in the case of promoter G4s, result in the transcriptional downregulation of these genes. However, structural information is currently available on only a very small number of G4s and their ligand complexes. This limitation, coupled with the currently restricted information on the G4-containing genes involved in most complex human cancers, has led to the development of a phenotypic-led approach to G4 ligand drug discovery. This approach was illustrated by the discovery of several generations of tri- and tetra-substituted naphthalene diimide (ND) ligands that were found to show potent growth inhibition in pancreatic cancer cell lines and are active in in vivo models for this hard-to-treat disease. The cycles of discovery have culminated in a highly potent tetra-substituted ND derivative, QN-302, which is currently being evaluated in a Phase 1 clinical trial. The major genes whose expression has been down-regulated by QN-302 are presented here: all contain G4 propensity and have been found to be up-regulated in human pancreatic cancer. Some of these genes are also upregulated in other human cancers, supporting the hypothesis that QN-302 is a pan-G4 drug of potential utility beyond pancreatic cancer.