In this article, we used an artificial DNA base to manipulate the formation of DNA nanoflowers (NFs) to easily control their sizes and functionalities. Nanoflowers have been reported as the noncanonical self-assembly of multifunctional DNA nanostructures, assembled from long DNA building blocks generated by rolling circle replication (RCR). They could be incorporated with myriad functional moieties. However, the efficacy of these DNA NFs as potential nanocarriers delivering cargo in biomedicine is limited by the bioavailability and therapeutic efficacy of their cargo. Here we report the incorporation of metal-containing artificial analogues into DNA strands to control the size and the functions of NFs. We have engineered bioinspired, size-controllable, self-degradable cancer-targeting DNA nanoflowers (Sgc8-NFs-Fc) via the incorporation of an artificial sandwich base. More specifically, the introduction of a ferrocene base not only resulted in the size controllability of Sgc8-NFs-Fc from 1000 to 50 nm but also endowed Sgc8-NFs-Fc with self-degradability in the presence of H 2 O 2 via Fenton's reaction. In vitro experiments confirmed that Sgc8-NFs-Fc/Dox could be selectively taken up by protein tyrosine kinase 7 (PTK7)-positive cancer cells and subsequently cleaved via Fenton's reaction, resulting in rapid release kinetics, nuclear accumulation, and enhanced cytotoxicity of their cargo. In vivo experiments further *

Exosomes (Exos) are nanoscale natural vehicles for transporting biomolecules to facilitate cell-tocell communication, indicating a high potential of them for delivering therapeutics/diagnostics. To improve their delivery capacity, a simple, noninvasive, and efficient strategy for functionalizing Exos with effective targeting ligands as well as elucidation of the cellular uptake mechanism of these functionalized Exos was found be to necessary, but remained a challenge. In this work, we used diacyllipid-aptamer conjugates as the targeting ligand to develop an aptamer-functionalized Exos (Apt-Exos) nanoplatform for cell type-specific delivery of molecular therapeutics. The cellular uptake mechanism of Apt-Exos was investigated in details, and distinct behavior was observed in comparison to free Exos. By combining the excellent molecular recognition capability of aptamers and the superiority of Exos as natural vehicles, Apt-Exos can efficiently deliver molecular drugs/fluorophores to target cancer cells, providing a promising delivery platform for cancer theranostics.

Automated attachment of chemotherapeutic drugs to oligonucleotides through phosphoramidite chemistry and DNA synthesis has emerged as a powerful technology in constructing structure-defined and payload-tunable oligonucleotide-drug conjugates. In practice, however, in vivo delivery of these oligonucleotides remains a challenge. Inspired by the systemic transport of hydrophobic payloads by serum albumin in nature, we report the development of a lipid-conjugated floxuridine homomeric oligonucleotide (LFU20) that "hitchhikes" with endogenous serum albumin for cancer chemotherapy. Upon intravenous injection, LFU20 immediately inserts into the hydrophobic cave of albumin to form an LFU20/albumin complex, which accumulates in the tumor by the enhanced permeability and retention (EPR) effect and internalizes into the lysosomes of cancer cells. After degradation, cytotoxic floxuridine monophosphate is released to inhibit cell proliferation.

Attachment of lipid tails to oligonucleotides has emerged as a powerful technology in constructing cell membrane-anchorable nucleic acid-based probes. In practice, however, conventional lipid-conjugated oligonucleotides fail to distinguish among different cell membranes. Herein, a phosphorylated lipid-conjugated oligonucleotide (DNA-lipid-P) is reported for alkaline phosphatase (ALP)-dependent cell membrane adhesion. In the absence of ALP, DNA-lipid-P with its poor hydrophobicity shows only weak interaction with cell membrane. However, in the presence of the highly expressed plasma membrane-associated ALP, DNA-lipid-P is converted to lipid-conjugated oligonucleotide (DNA-lipid) by enzymatic dephosphorylation. As a result of such conversion, the generated DNA-lipid has greater hydrophobicity than DNA-lipid-P and is thus able to insert into cell membranes in situ. Accordingly, DNA-lipid-P enables selective anchoring on cell membranes with elevated ALP level. Since elevated ALP level is a critical index of some diseases and even cancers, DNA-lipid-P holds promise for cell membrane engineering and disease diagnostics at the molecular level.

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