The construction of prodrugs has been a popular strategy to overcome the limitations of chemotherapeutic drugs. However, complicated synthesis procedures and laborious purification steps make the fabrication of amphiphilic prodrugs rather difficult. By harnessing the concept of host–guest interaction, we designed and prepared a supra-amphiphile consisting of a dendritic cyclodextrin host and an adamantane/naphthalimide-modified camptothecin guest through glutathione-responsive disulfide linkage. This host–guest complex could self-assemble in aqueous solution to give nanosized vesicles. When the disulfide bond in adamantane/naphthalimide-modified camptothecin was cleaved by glutathione, the fluorescence of the freed adamantane/naphthalimide unit showed a significant red shift with enhanced intensity. Such glutathione-responsive fluorescence change allows for intracellular imaging and simultaneous monitoring of drug release in real time. On account of abundant positively charged amine groups on the supramolecular vesicle surface, siRNA (siPlK1) could be efficiently loaded on the vesicle. The gel retardation and fluorescence experiments proved that the siPlK1 was successfully bonded to the supramolecular vesicle. The vesicle with dendritic cyclodextrin ring exhibited negligible cytotoxicity even at high concentrations, avoiding the shortcoming of cytotoxicity from commonly used gene vectors. In vitro studies demonstrated that the loaded siRNA was transported into cancer cells to improve cancer therapeutic efficacy. Thus, we developed a prodrug-based supramolecular amphiphile via the host–guest interaction with better therapeutic performance than free camptothecin. The assembled system was utilized as a drug/gene vector to achieve combinational gene therapy and chemotherapy with a synergistic effect, providing an alternative strategy to deliver both prodrug and therapeutic gene.Keywords: bioimaging; cancer therapy; host−guest interactions; prodrugs; vesicles;

Aptamers, that exist naturally in living cells as functional elements and can switch nonfluorescent natural targets to fluorophores, are very useful in developing highly sensitive and selective biosensors and screening functional agents. This work demonstrates that human telomeric G-quadruplex (HTG) can serve as a potential fluorophore-switching aptamer (FSA) to target a natural isoquinoline alkaloid. We found that, among the G-quadruplexes studied here and the various structurally similar alkaloids including epiberberine (EPI), berberine (BER), palmatine (PAL), jatrorrhizine (JAT), coptisine (COP), worenine (WOR), sanguinarine (SAN), chelerythrine (CHE), and nitidine (NIT), only the HTG DNA, especially with a 5′-TA-3′ residue at the 5′ end of the G-quadruplex tetrad (5′-TAG3(TTAG3)3-3′, TA[Q]) as the minimal sequence, is the most efficient FSA to selectively light up the EPI fluorescence. Compared to the 5′ end flanking sequences, the 3′ end flanking sequences of the tetrad contribute significantly less to the recognition of EPI. The binding affinity of EPI to TA[Q] (Kd = 37 nM) is at least 20 times tighter than those of the other alkaloids. The steady-state absorption, steady-state/time-resolved fluorescence, and NMR studies demonstrate that EPI most likely interact with the 5′ end flanking sequence substructure beyond the core [Q] and the G-quadruplex tetrad in a much more specific manner than the other alkaloids. The highly selective and tight binding of EPI with the FSA and significantly enhanced fluorescence suggest the potential development of a selective EPI sensor (detection limit of 10 nM). More importantly, EPI, as the brightest FSA emitter among the alkaloids, can also serve as an efficient conformation probe for HTG DNA and discriminate the DNA G-quadruplex from the RNA counterpart. Furthermore, EPI can bind stoichiometrically to each G-quadruplex unit of long HTG DNA multimer with the most significant fluorescence enhancement, which has not been achieved by the previously reported probes. Our work suggests the potential use of EPI as a bioimaging probe and a therapeutic DNA binder.

In order to overcome poor cell permeability of antisense peptide nucleic acid (PNA), a fluorescent mesoporous silica nanoparticle (MSNP) carrier was developed to successfully deliver antisense PNA into cancer cells for effective silence of B-cell lymphoma 2 (Bcl-2) protein expression in vitro. First, fluorescent MSNP functionalized with disulfide bond bridged groups was fabricated and characterized. Antisense and negative control PNAs were synthesized and further conjugated with fluorescent dye cyanine 5. Then, the PNAs were covalently connected with fluorescent MSNP via amidation between amino group of PNAs and carboxylic acid group on the MSNP surface. High intracellular concentration of glutathione serves as a natural reducing agent, which could cleave the disulfide bond to trigger the PNA release in vitro. Confocal laser scanning microscopy studies prove that PNA conjugated MSNP was endocytosed by HeLa cancer cells, and redox-controlled intracellular release of antisense PNA from fluorescent MSNP was successfully achieved. Finally, effective silencing of the Bcl-2 protein expression induced by the delivered antisense PNA into HeLa cells was confirmed by Western blot assay.