Enzyme Regulating the Wettability of the Outer Surface of Nanochannels

Abstract

Functional probes not only at the inner wall but also at the outer surface of nanochannel systems could be used for the recognition and detection of biotargets. Despite the advancements, the current detection mechanisms are still mainly based on the surface charge variation. We proposed a strategy of using the variation of wettability on the outer surface of nanochannels for detecting a tumor marker, herein, exemplifying matrix metalloproteinase-2 (MMP-2). The outer surface of the nanochannels were modified with amphipathic peptide probe consisting of hydrophilic unit (CRRRR), MMP-2 cleavage unit (PLGLAG), and hydrophobic unit (Fn). After recognition of MMP-2, due to the release of hydrophobic unit, the hydrophilicity of the outer surface was expected to increase, thus leading to the increase of ion current. Furthermore, the number (n) of phenylalanine (F) in the hydrophobic unit was modulated from 2, 4, to 6. By lengthening the hydrophobic unit, the limit of detection for MMP-2 detection could reach 1 ng/ mL (when n = 6) and improve by 50-fold (to n = 2). This nanochannel system was utilized to successfully detect the MMP-2 secreted from cells and demonstrated that the expression of MMP-2 was related to the cell cycle and exhibited the highest level in G1/S phase. This study proved that in addition to the surface charge, wettability regulation could also be utilized as a variation factor to broaden the design strategy of a probe on OS to achieve the detection of biotargets.

Outer-Surface Functionalized Solid-State Nanochannels for Enhanced Sensing Properties: Progress and Perspective

“…By utilizing changes in the wettability of the nanochannel's outer surface, an approach for detecting tumor markers, exemplified by matrix metalloproteinase-2 (MMP-2), was proposed (Figure 2B). 18 The limit of detection reached 100 ng/mL. Upon recognition by MMP-2, the release of the hydrophobic unit was expected to increase the hydrophilicity of the outer surface, leading to an increase in the ionic current.…”

Role of Outer Surface Probes on Bullet-Shaped Asymmetric Solid-State Nanochannels for Lysozyme Protein Sensing

“…Biological nanochannels, which play pivotal roles in numerous life processes, exhibit remarkable capabilities for precise recognition and rapid substance transfer between complex cytoplasmic solutions and tissue fluids. − Inspired by functionalities observed in biological nanochannels, including stimulus-responsive gating, ion pumping against electrochemical gradients, and generation of electrical signals, , there has been substantial development in artificial solid-state nanochannels. , These artificial nanochannels have found extensive applications due to their inherent advantages, such as adjustable geometry, , robust mechanical stability, , excellent biocompatibility, and favorable electrochemical properties. , Sensing technology represents the forefront of nanotechnology for artificial solid-state nanochannels, garnering significant attention and showing promise in applications such as DNA sequencing and clinical diagnosis, among others. While there has been substantial research in the field of nanochannel sensing in molecular biology and medicine, the pursuit of enhanced anti-interference capabilities and sensitivity remains a formidable challenge in realizing the full potential of solid-state nanochannels.…”

“…8,9 These artificial nanochannels have found extensive applications due to their inherent advantages, such as adjustable geometry, 10,11 robust mechanical stability, 12,13 excellent biocompatibility, 14 and favorable electrochemical properties. 15,16 Sensing technology represents the forefront of nanotechnology for artificial solid-state nanochannels, garnering significant attention and showing promise in applications such as DNA sequencing 17 and clinical diagnosis, 18 among others. While there has been substantial research in the field of nanochannel sensing in molecular biology and medicine, the pursuit of enhanced anti-interference capabilities and sensitivity remains a formidable challenge in realizing the full potential of solid-state nanochannels.…”

“…While much attention has been directed toward functional elements immobilized on the inner wall of nanochannels, those on the outer surface were often overlooked for an extended period. , In recent years, researchers have increasingly focused on constructing and utilizing functional elements on the outer surface within the confined space of nanochannels . The probes on the outer surface (P OS ) are comparatively easier to modify and characterize compared to probes on the inner wall (P IW ), making it particularly useful for the analysis of large biomarkers such as proteins, viruses, and cellsa task that can be challenging when dealing with P IW . Moreover, in 2018, our research group reported that P OS played a crucial synergistic role alongside P IW in nanochannels with a cylindrical structure, particularly in the context of ion gating .…”

Detection of Unfolded Cellular Proteins Using Nanochannel Arrays with Probe‐Functionalized Outer Surfaces

“…This approach requires that the biotargets to enter the nanochannel for detection. [12] However, this approach faces several limitations pertaining to the detection of protein conformation. Firstly, the nonuniform distribution of positive and negative charges within proteins could lead to various translocation patterns influenced by the driving force.…”