Enzymatically Controlled Nanoflares for Specific Molecular Recognition and Biosensing

Abstract

In situ sensing of physiological and pathological species in cancer cells is of great importance to unravel their molecular and cellular processes. However, the biosensing with conventional probes is often limited by the undesired on-target off-tumor interference. Here, we report a novel strategy to design enzymatically controlled nanoflares for sensing and imaging molecular targets in tumor cells. The triggerable nanoflare was designed via rational engineering of structure-switching aptamers with the incorporation of an enzyme-activatable site and further conjugation on gold nanoparticles. The nanoflare sensors did not respond to target molecules in normal cells, but they could be catalytically activated by specific enzymes in cancer cells, thereby enabling cancer-specific sensing and imaging in vitro and in vivo with improved tumor specificity. Considering that diverse aptamers were selected, we expect that this strategy would facilitate the precise detection of a broad range of targets in tumors and may promote the development of smart probes for cancer diagnosis.

Fluorescence-Enhanced Dual-Driven “OR-AND” DNA Logic Platform for Accurate Cell Subtype Identification

“…Owing to the advantages of precise programmability and computational features, DNA logic platforms activated by endogenous substances in cells provide unprecedented opportunities for logic analysis of a single disease-related biomolecule to enhance the accuracy of cell subtype identification. , Currently, most reported DNA logical platforms for cell subtype identification mainly use the cell-specific membrane proteins stimulation response as input, and cell subtype identification can be achieved based on the different signal outputs caused by different membrane protein stimulation responses on the cell surface. − However, the heterogeneous spatial distribution of membrane proteins on the cell membrane is difficult to ensure the logical computation inputs, thereby leading to the “false negative” logic operation results and further affecting the accuracy of cell identification. , It is worth noting that if these missing logical computation inputs can be turned on again by endogenous substances in tumor cytoplasm, such as apurinic/apyrimidinic endonuclease 1 (APE 1), not only the false negative result can be avoided, but also the efficiency of the logic operation can be improved. In addition, another significant limitation is the insufficient sensitivity caused by photobleaching for detection of intracellular low-abundance targets. , To solve this problem, plasmon-enhanced fluorescence (PEF) has been considered as an effective strategy to break through such bottleneck and improve detection sensitivity. − Consequently, using membrane proteins and an APE 1 stimulation response that at different spatial locations in the cells as input to construct a dual-driven DNA logic platform together with the PEF technique is expected to improve the accuracy of cell subtype identification.…”

“…Owing to the advantages of precise programmability and computational features, DNA logic platforms activated by endogenous substances in cells provide unprecedented opportunities for logic analysis of a single disease-related biomolecule to enhance the accuracy of cell subtype identification. 15,16 Currently, most reported DNA logical platforms for cell subtype identification mainly use the cellspecific membrane proteins stimulation response as input, and cell subtype identification can be achieved based on the different signal outputs caused by different membrane protein stimulation responses on the cell surface. 17−21 However, the heterogeneous spatial distribution of membrane proteins on the cell membrane is difficult to ensure the logical computation inputs, thereby leading to the "false negative" logic operation results and further affecting the accuracy of cell identification.…”

An Enzymatically Gated Catalytic Hairpin Assembly Delivered by Lipid Nanoparticles for the Tumor‐Specific Activation of Signal Amplification in miRNA Imaging

“…In the design, human apurinic/apyrimidinic endonuclease 1 (APE1), an essential enzyme in base excision repair process, has been selected as the endogenous stimuli. Many studies reveal that APE1 is highly expressed in cytoplasm of cancer cells, but mainly exist in the nuclear region in normal cells, [39, 40] thus has been used for triggering biosensing specifically in cancer cells [23, 24, 41, 42] . The principle of E‐CHA has been depicted in Figure 1a.…”

“…Many studies reveal that APE1 is highly expressed in cytoplasm of cancer cells, but mainly exist in the nuclear region in normal cells, [39,40] thus has been used for triggering biosensing specifically in cancer cells. [23,24,41,42] The principle of E-CHA has been depicted in Figure 1a. In E-CHA system, the enzyme-responsive molecular beacon (EMB) was designed by introducing an abasic (AP) site (the red part), which was located at 8 th nucleotides from the 3'-end of EMB in the stem region.…”

Protein-Scaffolded DNA Nanostructures for Imaging of Apurinic/Apyrimidinic Endonuclease 1 Activity in Live Cells

“…Human apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional enzyme that plays crucial roles in base excision repair and gene regulation. , As a base repair enzyme, APE1 recognizes and exerts an incision adjacent to 5′ of an abasic site, generating a nick in the phosphodiester backbone to initiate base repairing . APE1 is overexpressed in various cancer cells and has been identified as a diagnostic biomarker and therapeutic target. − Intracellular imaging of APE1 would provide useful information for cancer diagnosis, prognosis, and treatment evaluation.…”