Naphthalene Diimide Derivatives Research Articles

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.

Self-Assembly of Amphiphilic PDI and NDI Derivatives with Opposite Thermoresponsive Fluorescent Behaviors in Aqueous Solution.

This work presents a study of the thermally induced aggregation of perylene diimide (PDI) and naphthalene diimide (NDI) derivatives modified with oligo ethylene glycol (OEG) chains in aqueous solution. Water-soluble and flexible OEG side chains were introduced into the π-core of glutamate-modified NDI and PDI structures, and the aggregation process was modulated by heating or cooling in water. Interestingly, a rare opposite temperature response of fluorescent behavior from the two amphiphilic chromophores was revealed, in which the PDI exhibited fluorescent enhancement, while fluorescent quenching upon temperature increase was observed from the NDI assembly. The mechanism of thermally induced aggregation is clearly explained by studies with various spectroscopic techniques including UV-visible, fluorescence, 1H NMR, 2D NMR spectroscopy, and SEM observation as well as control experiments operated in DMSO solution. It is found that although similar J-aggregates were formed by both amphiphilic chromophores in aqueous solution, the temperature response of the aggregates to temperature was opposite. The degree of PDI aggregation decreased, while that of NDI increased upon temperature rising. This research paves a valuable way for understanding the complicated supramolecular behaviors of amphiphilic chromophores.

Thiolated Chiral Naphthalene Diimide Derivatives as Effective Selectors of the β‐Blocker Atenolol Enantiomers

AbstractAtenolol β‐blocker drug (ATN) to treat hypertension and cardiovascular disorders such as angina pectoris is manufactured commercially in a racemic form, while only its (S)‐enantiomer shows selective β1‐blocking activity. Here, a new axially chiral thiolated naphthalene diimide derivatives (HS‐BIN‐NDI) for the rapid, simple, and sensitive detection of ATN enantiomers is presented. The Surface Plasmon Resonance (SPR) and Atomic Force Microscopy (AFM) experiments show that interactions between a chiral selector and a chiral analyte occur only when their configurations are opposite. The extensive computational simulations support this finding. The association coefficient determined by SPR is high (105‐106 M−1 s−1) and indicates that the interactions are electrostatic. The analytical utility of atropisomeric HS‐BIN‐NDIs is proven, and the voltammetric sensors designed to determine ATN enantiomers are constructed. The developed sensors are characterized by a wide analytical operating range from 5.0·10−3 to 1.0 µm, nanomolar detection limit, high selectivity, and a long lifetime. Several additives like urea, creatinine, glucose, human albumin, and hemoglobin do not affect ATN sensing.

G-quadruplex structural dynamics at MAPK12 promoter dictates transcriptional switch to determine stemness in breast cancer.

P38γ (MAPK12) is predominantly expressed in triple negative breast cancer cells (TNBC) and induces stem cell (CSC) expansion resulting in decreased survival of the patients due to metastasis. Abundance of G-rich sequences at MAPK12 promoter implied the functional probability to reverse tumorigenesis, though the formation of G-Quadruplex (G4) structures at MAPK12 promoter is elusive. Here, we identified two evolutionary consensus adjacent G4 motifs upstream of the MAPK12 promoter, forming parallel G4 structures. They exist in an equilibria between G4 and duplex, regulated by the binding turnover of Sp1 and Nucleolin that bind to these G4 motifs and regulate MAPK12 transcriptional homeostasis. To underscore the gene-regulatory functions of G4 motifs, we employed CRISPR-Cas9 system to eliminate G4s from TNBC cells and synthesized a naphthalene diimide (NDI) derivative (TGS24) which shows high-affinity binding to MAPK12-G4 and inhibits MAPK12 transcription. Deletion of G4 motifs and NDI compound interfere with the recruitment of the transcription factors, inhibiting MAPK12 expression in cancer cells. The molecular basis of NDI-induced G4 transcriptional regulation was analysed by RNA-seq analyses, which revealed that MAPK12-G4 inhibits oncogenic RAS transformation and trans-activation of NANOG. MAPK12-G4 also reduces CD44High/CD24Low population in TNBC cells and downregulates internal stem cell markers, arresting the stemness properties of cancer cells.

Realizing one-step two-electron transfer of naphthalene diimides via a regional charge buffering strategy for aqueous organic redox flow batteries.

Naphthalene diimide derivatives show great potential for application in neutral aqueous organic redox flow batteries (AORFBs) due to their highly conjugated molecular structure and stable two-electron storage capacity. However, the two-electron redox process of naphthalene diimides typically occurs via two separate steps with the transfer of one electron per step ("two-step two-electron" transfer process), which leads to an inevitable loss of voltage and energy. Herein, we report a novel regional charge buffering strategy that utilizes the core-substituted electron-donating group to adjust the redox properties of naphthalene diimides, realizing two electron transfer via a single-step redox process ("one-step two-electron" transfer process). The symmetrical battery testing of NDI-DEtOH revealed exceptional intrinsic stability lasting for 11 days with a daily decay rate of only 0.11%. Meanwhile, AORFBs with NDI-DMe/FcNCl and NDI-DEtOH/FcNCl exhibited a remarkable 40% improvement in peak power density at 50% state of charge (SOC) in comparison to NDI/FcNCl-based AORFBs. In addition, the battery's energy efficiency has increased by 24%, resulting in much more stable output power and significantly improved energy efficiency. These results are of great significance to practical applications of AORFBs.

Naphthodithiophene Diimide (NDTI)‐Based Cathode Interlayer Material Enables 19% Efficiency Binary Organic Solar Cells

AbstractA fused naphthodithiophene diimide (NDTI) derivative is first used as cathode interlayer materials (CIMs) in organic solar cells, by introducing two dimethylamine‐functionalized fluorenes on both sides, namely NDTI1. Meanwhile, two non‐fused naphthalene diimide (NDI) derivatives are synthesized as the control CIMs to validate the design strategy of fused NDI. All three CIMs show high thermal stability, robust adhesion, and strong electrode modification capability. Compared with two NDI‐based materials, NDTI1 possesses excellent film‐forming capacity and strong crystallinity, simultaneously. Besides, NDTI1 presents a strong self‐doping effect and distinct intermolecular interaction with non‐fullerene acceptors. As expected, the NDTI1‐based OSCs achieve a power conversion efficiency (PCE) of 18.02% using the PM6:Y6 active layer and a champion PCE of 19.01% employing the active layer PM6:L8‐BO, which is attributed to improve charge transport and extraction, and suppressive charge recombination. More importantly, NDTI1 retains 91% of the optimal PCE when the film thickness increases from 7 to 20 nm. Furthermore, NDTI1 also exhibits satisfactory universality for different active layer materials and excellent device stability.

Noncovalent Dualism in Perylene-Diimide-Based Keggin Anion Complexes: Theoretical and Experimental studies.

We report the synthesis and comprehensive characterization of organic-inorganic hybrid salts formed by bis-cationic N,N'-bis(2-(trimethylammonium)ethylene)perylene-3,4,9,10-tetracarboxylic acid bisimide (PTCD2+) and Keggin-type [XW12O40]n- (X = Si, n = 4; X = P, n = 3) polyoxometalates. (PTCD)3[PW12O40]2·3DMSO·2H2O (2) and (PTCD)2[SiW12O40]·DMSO·2H2O (3) were structurally characterized by single crystal X-ray diffraction. The cations in both structures exhibited infinite chainlike arrangements through π-π interactions, contrasting with the previously reported cation-anion stacking observed in naphthalene diimide derivatives. A detailed theoretical study employing topological analysis of the electron density distribution within the quantum theory of atoms in molecules approach provided further insights into this structural dualism. Atomic force microscopy analyses revealed the formation of self-assembled supramolecular structures on graphite from molecular monolayers (3 nm of thick) to submicrometer aggregates for 2. Hyperspectral Raman spectroscopy imaging revealed that such heterostructures are likely formed by an enhanced π-π interactions. Both complexes demonstrated interesting electrochemical behavior, photoluminescence and X-ray-induced luminescence. Electron spin resonance analysis confirmed charge separation in both compounds, with enhanced efficiency observed in compound 2. Our findings of these perylene-based organic-inorganic hybrid salts offer the potential for their application in optoelectronic devices and functional materials.

A comprehensive analysis of electronic transitions in naphthalene and perylene diimide derivatives through computational methods

AbstractPerylene diimide (PDI) and naphthalene diimides (NDIs) are compounds widely used in supramolecular structures due to their versatile and functional properties. They have high absorptions and photoluminescence capabilities, which make them ideal for electronic transition studies. Reflux method, a widely employed synthetic technique, was utilized to synthesize NDI and PDI derivatives. In this method, the respective amino acids and NTDA (naphthalene‐1,4,5,8‐tetracarboxylic dianhydride) were combined in acetic acid and the resulting mixture was subjected to reflux. This study centered on a diverse set of NDI and PDI ligands, comprising L‐ala‐NDI, B‐ala‐NDI, Gly‐NDI, Imi‐NDI, Pyr‐NDI, L‐ala‐PDI, B‐ala‐PDI, Gly‐PDI, Imi‐PDI, and Pyr‐PDI ligands. Crystal structures were obtained for three NDI ligands, while the characterization of all ligands involved several analytical techniques such as NMR, IR, UV, DFT, TD‐DFT calculations, and single‐crystal x‐ray crystallography specifically for the NDI ligands. The investigation focused on studying the electron acceptor/donor behavior of the NDI and PDI ligands, identifying their potential for charge transfer applications. Furthermore, the NLO (nonlinear optical) response of all 10 NDI and PDI ligands was assessed through an analysis involving HOMO‐LUMO, TDM, EDDM, NCI, Iso‐surface, MEP, natural population, and DOS analysis. This evaluation encompassed the examination of linear polarizability, as well as first and second hyperpolarizability in the context of NLO. The findings of the study revealed that Gly‐PDI, Imi‐PDI, L‐ala‐PDI, and B‐ala‐PDI ligands displayed a higher NLO response compared with the other ligands. These results highlight the potential of these ligands for nonlinear optical applications. The comprehensive characterization and assessment of the NDI and PDI ligands contribute to a deeper understanding of their electron properties, positioning them as promising candidates for charge transfer and nonlinear optical materials.

A Supramolecular Naphthalene Diimide Radical Anion with Efficient NIR-II Photothermal Conversion for E. coli-Responsive Photothermal Therapy.

We report a supramolecular naphthalene diimide (NDI) radical anion with efficient NIR-II photothermal conversion for E. coli-responsive photothermal therapy. The supramolecular radical anion (NDI-2CB[7])⋅- , which is obtained from the E. coli-induced in situ reduction of NDI-2CB[7] neutral complex, formed by the host-guest interaction between an NDI derivative and cucurbit[7]uril (CB[7]), exhibits unexpectedly strong NIR-II absorption and remarkable photothermal conversion capacity in aqueous solution. The NIR-II absorption is caused by the self-assembly of NDI radical anions to form supramolecular dimer radicals in aqueous solution, which is supported by theoretically predicted spectra. The (NDI-2CB[7])⋅- demonstrates excellent NIR-II photothermal antimicrobial activity (>99 %). This work provides a new approach for constructing NIR-II photothermal agents and non-contact treatments for bacterial infections.

A Supramolecular Naphthalene Diimide Radical Anion with Efficient NIR‐II Photothermal Conversion for E. coli‐Responsive Photothermal Therapy

AbstractWe report a supramolecular naphthalene diimide (NDI) radical anion with efficient NIR‐II photothermal conversion for E. coli‐responsive photothermal therapy. The supramolecular radical anion (NDI‐2CB[7])⋅−, which is obtained from the E. coli‐induced in situ reduction of NDI‐2CB[7] neutral complex, formed by the host–guest interaction between an NDI derivative and cucurbit[7]uril (CB[7]), exhibits unexpectedly strong NIR‐II absorption and remarkable photothermal conversion capacity in aqueous solution. The NIR‐II absorption is caused by the self‐assembly of NDI radical anions to form supramolecular dimer radicals in aqueous solution, which is supported by theoretically predicted spectra. The (NDI‐2CB[7])⋅− demonstrates excellent NIR‐II photothermal antimicrobial activity (>99 %). This work provides a new approach for constructing NIR‐II photothermal agents and non‐contact treatments for bacterial infections.

Effect of substituents of naphthalene diimide derivatives on electrochromic behaviours observed in proto-type devices

Several triphenylamine end capped to substituted central naphthalenetetracarboxylic diimide based four donor - acceptor - donor type electro-active monomers (BRTPANDI, CNTPANDI, PHTPANDI, NPYTPANDI) were designed and developed to explore the effect of substituent on the formation of electro-polymers and subsequent the chromic effect of prepared films on the conductive surface. Initially, with the help of density functional theory (DFT) studies, it was observed that HOMO was located over triphenylamine unit, responsible electro-polymerization process upon oxidation, LUMO was residing on the central naphthalene core, and all substituents were not coplanar with naphthalene moiety. Also, the band gap energy was gradually decreased with the effect of strong electron withdrawing substituents on NDI core. In three electrode configuration, reversible multiple colour changes of brown to deep blue by applying voltage 0 to 1.1 V and also brown to deep pink with the voltage change of 0 to −2 V were impressively investigated with relatively good response times, optical contrast, switching stabilities, and coloration efficiencies. Polymer made of CNTPANDI might be switched upto 1200 cycles with the optimum colouration efficiency 560 cm2/C in the anodic process and 300 cycles for the cathodic process in a three electrodes configuration. Proto type devices made of p-CNTPANDI demonstrated the electrochromism operated at a potential range of 0 to 2.2 V. Besides, the device exhibited the EC memory in open-circuit condition with 50% retention of its coloured state until 27 min. The long EC memory as well as high colouration efficiency compared to other TPA based conjugated polymers suggested the potentiality of those polymer films as a power-efficient EC material for modern display applications.

High-voltage and durable pH-neutral aqueous redox flow batteries based on quaternary ammonium cations functionalized naphthalene diimide and nitroxyl radical systems

Aqueous organic redox flow batteries (AORFBs) are regarded as one of the most promising battery systems for grid-scale and sustainable energy storage, but the longstanding problems, typically, low energy density and inferior cycling stability, must be resolved. Herein, highly water-soluble naphthalene diimide (NDI) derivatives modified with two positively charged and hydrophilic ammonium terminals are synthesized and used as two-electron anolytes for AORFBs. The redox chemistry of NDI molecules is understood by cyclic voltammetry and the corresponding Pourbaix diagram, indicating the two single-electron processes without being protons under neutral pH conditions. Interestingly, the crossover of 4-ammonium-(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (NMe-TEMPO) species occurs, but the hydrogenation reaction of crossed NMe-TEMPO in the anolyte is significantly inhibited, thus alleviating the capacity degradation of AORFBs. As a result, the NDI/NMe-TEMPO AORFBs deliver no distinct capacity decay over 1300 cycles and a stable cycling life over 3500 cycles with 0.00394% capacity fade rate per cycle, which is one of the representative examples among the existing pH-neutral AORFBs. This work clarifies the capacity decay and two single-electron reduction mechanisms and presents a significant advancement for constructing high-voltage and durable pH-neutral AORFBs based on the two-electron naphthalene diimide and nitroxyl radical systems.

Does Twisted Molecular Structure Always Induce Intersystem Crossing? A Case Study with Near-IR Absorbing 1,8-Diazabicyclo[5.4.0]undec-7-ene-fused Naphthaldiimide.

Heavy atom-free organic chromophores showing absorption in the near-IR region with intersystem crossing (ISC) ability are important for applications in various fields, e.g., photocatalysis and photodynamic therapy. Herein, we studied the photophysical property of a naphthalenediimide (NDI) derivative, in which the NDI chromophore is fused with pentacyclic 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), which shows a strong charge-transfer (CT) absorption band (S0 → 1CT transition) in the near-IR region of 600-740 nm. The effect of extended π-conjugation framework in NDI-DBU compared with the derivative of mono-amino substitution (NDI-NH-Br) was studied by steady-state and nanosecond transient absorption (ns-TA) spectra, electron paramagnetic resonance (EPR) spectroscopy, and theoretical computations. The fluorescence is almost completely quenched for NDI-DBU (ΦF = 1.0%) as compared with NDI-NH-Br (ΦF = 24% in toluene). However, the ISC of NDI-DBU is poor, and the singlet oxygen quantum yield was determined as ΦΔ = 9% versus ΦΔ = 57% for NDI-NH-Br, although the compound has significantly twisted molecular structure. The ns-TA spectral study showed a long-lived triplet excited state (τT = 132 μs) in NDI-DBU, with T1 energy of 1.20-1.44 eV, and the ISC is via the S2 → T3 path, which is verified by theoretical calculations. This study displayed that the twisting of molecular geometry does not always assure efficient ISC.

Separation of Cyclohexanone and Cyclohexanol by Adaptive Pillar[5]arene Cocrystals Accompanied by Vapochromic Behavior.

The separation of cyclohexanone (CHA-one) and cyclohexanol (CHA-ol) mixtures is of great importance in the chemical industry. Current technology exploits multiple steps of energy-intensive rectification due to their close boiling points. Herein, we report a new and energy-efficient adsorptive separation method employing binary adaptive macrocycle cocrystals (MCCs) built with π-electron-rich pillar[5]arene (P5) and an electron-deficient naphthalenediimide derivative (NDI) that can selectively separate CHA-one from an equimolar CHA-one/CHA-ol mixture with >99% purity. Intriguingly, this adsorptive separation process is accompanied by vapochromic behavior from pink to dark brown. Single-crystal and powder X-ray diffraction analyses reveal that the adsorptive selectivity and vapochromic property are derived from the CHA-one vapor inside the cocrystal lattice voids triggering solid-state structural transformations to yield charge-transfer (CT) cocrystals. Moreover, the reversible transformations make the cocrystalline materials highly recyclable.

Organic nanoparticles with tunable AIE derived from amino acids appended naphthalenediimide based amphiphiles

Fluorescent organic nanoparticles (FONPs) are unique cooperative manifestations of supramolecular self-aggregates and luminescent nanoparticles. In this work, we developed naphthalenediimide (NDI) based amphiphiles (NDI-1-9) having amino acids substitution from L-alanine to L-phenyl alanine to 3-(2-naphthyl)-L-alanine in absence and presence of alkyl spacer (C-6, C-11). Formation of self-aggregated spherical organic nanoparticles of ∼50 nm took place at and above 50 vol% water or methyl cyclohexane (MCH) in different binary solvent systems (DMSO/DMF-water, CHCl3-MCH) via J-aggregation. In case of NDI-1-3 (amino acids are directly connected to the NDI) self-assembled FONPs (MCH in CHCl3) exhibited aggregation-induced emission (AIE) through excimer formation. Red shift in the emission maxima were observed from 484 nm to 495 nm, and 590 nm, respectively with increasing π electron cloud at substituted donor from NDI-1 to NDI-3. Alongside, in case of aromatic amino acids substitution, FONPs of 6-amino caproic acid spacer containing NDI derivatives (NDI-5 and NDI-6) showed AIE at 505 nm and 545 nm (water in DMF/DMSO). Corresponding 11-amino undecanoic acid containing analogues (NDI-8 and NDI-9) showed AIE at 480 nm and 585 nm in CHCl3-MCH and DMF/DMSO-water. The multi colour emission from blue-green to yellow-orange with enrichment of π-electron cloud density in the side chain substitution of NDI was observed possibly due to the facilitated electron transfer at a lesser energy to the electron deficient NDI core that resulted in red shifted emission maxima. This was further clarified by regulating the availability of π-electrons of phenyl ring of NDI-2 by including electron withdrawing –NO2 and donating -OMe groups at the molecular backbone (NDI-2a and NDI-2b) that showed blue shifted (475 nm) and red shifted (570 nm) emission maxima with respect to NDI-2 (495 nm). However, increase in alkyl spacer length between side chain substitution and NDI core yielded relatively lower quantum yield presumably due to the impeded electron transfer.

Anion−π Interactions in Monolayers Formed by Amphiphilic Electron-Deficient Aromatic Compounds at Air/Water Interfaces

Biological systems precisely and selectively control ion binding through various chemical reactions, molecular recognition, and transport by virtue of effective molecular interactions with biological membranes and proteins. Because ion binding is inhibited in highly polar media, recognition systems for anions in aqueous media, which are relevant to biological and environmental systems, are still limited. In this study, we explored the anion binding of Langmuir monolayers formed by amphiphilic naphthalenediimide (NDI) derivatives with a series of substituents at air/water interfaces via anion-π interactions. Density functional theory (DFT) simulations revealed that the binding of anions originating from anion-π interactions is related to the electron density of the anions. At the air/water interfaces, amphiphilic NDI derivatives formed Langmuir monolayers, and the addition of anions caused expansion of the Langmuir monolayers. The anions with larger hydration energies related to electron density showed larger binding constants (Ka) for 1:1 stoichiometry with the NDI derivatives. The loosely packed monolayer formed by the amphiphilic NDI derivatives with bromine groups showed a better anion response. In contrast, the binding of NO3- was significantly enhanced in the highly packed monolayer. These results indicate that the packing of NDI derivatives with rigid aromatic rings influenced the binding of the anions. These results provide insight into ion binding using the air/water interface as a promising recognition site for mimicking biological membranes. In future, sensing devices can be developed using Langmuir-Blodgett films on electrodes. Furthermore, the capture of anions on electron-deficient aromatic compounds can lead to doping or composition technologies for n-type semiconductors.

Abstract 4981: The potent quadruplex-binding compound QN-302 down-regulates the S100P gene in in vitro and in vivo models of pancreatic cancer: a potential therapeutic target and biomarker for PDAC

Abstract The compound QN-302, a tetra-substituted naphthalene diimide (ND) derivative has been designed to have high affinity for G-quadruplex (G4) nucleic acids. It has single-digit nM anti-proliferative activity in a panel of human pancreatic cancer cell lines (Ahmed et al., ACS Med Chem Lett, 2020, 11, 1634-1644) and anti-tumor activity in xenograft, orthotopic and genetic (KPC) models for pancreatic cancer (PDAC). Its mode of action involves the targeting of G4-forming sites in promoter regions of cancer-associated genes, where their prevalence is over-represented compared to other genes. Transcriptome analyses of QN-302 in MIA-PACA2 cells have confirmed genes involved in cancer-associated pathways and carry G4 motifs in their promoters as targets. We have found that expression of the S100P gene, a well-authenticated indicator of PDAC disease and progression, is highly down-regulated in QN-302 treated cells. The S100P gene contains at least five putative G4 motifs, including a classic G4 promoter site just upstream of the transcription start site. We have observed that transcriptome analyses on tumor material from human PDAC patients, and those from poorly differentiated as well as more highly differentiated tumors, have shown that the S100P gene is highly over-expressed (especially in poorly differentiated tumors). We now report on gene expression analysis of S100P using control and treated tumor tissues from a therapeutic study in PDAC MIA-PACA2 xenografts in mice, by means of RT-qPCR and Western blot analyses. The data shows statistically significant dose-dependent decreases in expression of S100P at both the mRNA (to ca 25% of control values) and protein levels (to ca 22% of control values), giving added confidence to the concept that the S100P gene is a therapeutic target in PDAC and may also be useful as a marker of QN-302 response in future clinical use. QN-302 is bio-available at therapeutic doses and is well tolerated at these levels in the animal models. It is being developed for clinical evaluation by Qualigen Therapeutics Inc and is currently at the pre-IND stage. Citation Format: Nicole Williams, Jenny Worthington, Ahmed Ahmed, Tariq Arshad, Stephen Neidle. The potent quadruplex-binding compound QN-302 down-regulates the S100P gene in in vitro and in vivo models of pancreatic cancer: a potential therapeutic target and biomarker for PDAC. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4981.

Abstract 3098: Structure-based design rules for potent quadruplex-binding compounds based on the naphthalene diimide core

Abstract Quadruplex nucleic acids (G4s) are four-stranded arrangements formed by guanine-rich tracts of DNA or RNA, held together by Hoogsteen hydrogen-bonded guanine quartets. G4 sequences are widely though not randomly distributed in the human genome. They are over-represented in telomeres and in the regulatory regions of many cancer-related genes such as KIT, MYC, VEGF, RAS and HIF. G4 structures can be unwound by helicase activity but can be stabilized by the binding of high-affinity small molecules. The compound QN-302, a tetra-substituted naphthalene diimide (ND) derivative, has nanomolar affinity and selectivity for several DNA and RNA G4s over duplex DNA. QN-302 has single-digit nM anti-proliferative activity in a panel of human pancreatic cancer (PDAC) cell lines (Ahmed et al., ACS Med Chem Lett, 2020, 11, 1634-1644). It has significant anti-tumor activity in several models for PDAC - in a MIA-PACA2 xenograft, in the genetic KPC model and in an orthotopic BX-PC3 model. QN-302 is currently in an advanced stage of pre-IND development by Qualigen Inc as a novel anti-cancer agent. QN-302 is the latest in several generations of NDs developed by us and designed by computer modelling based on earlier G4 co-crystal structures determined in this laboratory. The database of seven ND-containing crystal structures includes four different NDs with distinct side chain end groups, all with intramolecular telomeric parallel G4s. End-groups include N-methyl piperazine, hydroxyl, morpholino and N-dimethyl. These structures have been systematically compared for example using least-squares overlays of the structures. All the structures have their four substituents positioned each in a G4 groove, although there are significant differences in orientations of the end groups. Surprisingly, the naphthalene diimide cores do not retain the same orientation in each structure, with three distinct orientations being apparent. Examination of ND core overlap with the adjacent G-quartet has revealed variation in the degree of heterocycle-guanine base overlap, which is dependent on the nature and size of each substituent. However, all structures show minimal ND-guanine overlap, with typically just one out of four guanines in a G-quartet being involved. This strongly implies that most of the contribution to ND-G4 affinity comes from the side chains, and especially from the protonated end groups. These and other observations have led us to develop a structure-activity framework for tetra-substituted NDs, which has culminated in their optimization and the design of QN-302, with enhanced cellular potency and G4 affinity compared to previous NDs. Citation Format: Stephen Neidle. Structure-based design rules for potent quadruplex-binding compounds based on the naphthalene diimide core [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3098.

Abstract 6240: The potent quadruplex-binding compound QN-302 shows anti-tumor activity as a monotherapy in an orthotopic in vivo model of pancreatic cancer

Abstract The compound QN-302, a tetra-substituted naphthalene diimide derivative has single-digit nM anti-proliferative activity in a panel of human pancreatic cancer (PDAC) cell lines (Ahmed et al., ACS Med Chem Lett, 2020, 11, 1634-1644). It has significant anti-tumor activity in the MIA-PACA2 xenograft model for PDAC and in the genetic KPC model. We now report that this compound also shows significant mono-therapy anti-tumor activity in an orthotopic model for PDAC. Female athymic nude mice bearing orthotopically implanted pancreatic BxPC-3 cells were dosed with 1 x weekly IV QN-302 at 0.5 and 1.0 mg/kg, over a period of 21 days. A separate group of mice was treated with Gemcitabine twice weekly IV during this period, at a dosage of 15 mg/kg. Blood samples from animals were collected on a weekly basis and were used to detect and quantify circulating tumor DNA as a method of following treatment efficacy. In line with previous studies QN-302 was well-tolerated at 0.5 and 1.0 mg/kg with no adverse effects on animal health or behavior noted during the study. Circulating tumor DNA levels were significantly less than vehicle controls in gemcitabine-treated animals from day 7 and QN-302 (1.0 mg/kg) treated animals from day 14 of treatment. Survival was significantly increased in gemcitabine and QN-302 (1.0 mg/kg) QW treatment groups. Statistically significant efficacy was observed in gemcitabine and QN-302 (1.0 mg/kg) treated animals. Examination of blood chemistry and biochemistry of treated animals did not indicate any adverse effects due to QN-302. This orthotopic model is the 4th in vivo study in a pancreatic cancer model showing anti-tumor activity for QN-302, further confirming the potential of this compound for human disease. QN-302 is currently in an advanced stage of pre-IND development by Qualigen Inc. Citation Format: Nicole Williams, Danielle Santos, Jenny Worthington, Ahmed Ahmed, Tariq Arshad, Stephen Neidle. The potent quadruplex-binding compound QN-302 shows anti-tumor activity as a monotherapy in an orthotopic in vivo model of pancreatic cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6240.

CRGD-Functionalized Silk Fibroin Nanoparticles: A Strategy for Cancer Treatment with a Potent Unselective Naphthalene Diimide Derivative

Developing drug delivery systems to target cytotoxic drugs directly into tumor cells is still a compelling need with regard to reducing side effects and improving the efficacy of cancer chemotherapy. In this work, silk fibroin nanoparticles (SFNs) have been designed to load a previously described cytotoxic compound (NDI-1) that disrupts the cell cycle by specifically interacting with non-canonical secondary structures of DNA. SFNs were then functionalized on their surface with cyclic pentapeptides incorporating the Arg-Gly-Asp sequence (cRGDs) to provide active targeting toward glioma cell lines that abundantly express ανβ3 and ανβ5 integrin receptors. Cytotoxicity and selective targeting were assessed by in vitro tests on human glioma cell lines U373 (highly-expressing integrin subunits) and D384 cell lines (low-expressing integrin subunits in comparison to U373). SFNs were of nanometric size (d50 less than 100 nm), round shaped with a smooth surface, and with a negative surface charge; overall, these characteristics made them very likely to be taken up by cells. The active NDI-1 was loaded into SFNs with high encapsulation efficiency and was not released before the internalization and degradation by cells. Functionalization with cRGDs provided selectivity in cell uptake and thus cytotoxicity, with a significantly higher cytotoxic effect of NDI-1 delivered by cRGD-SFNs on U373 cells than on D384 cells. This manuscript provides an in vitro proof-of-concept of cRGD-silk fibroin nanoparticles' active site-specific targeting of tumors, paving the way for further in vivo efficacy tests.