Programmable Modular Assembly of Functional Proteins on Raman-Encoded Zeolitic Imidazolate Framework-8 (ZIF-8) Nanoparticles as SERS Tags

Abstract

Zeolitic imidazolate framework-8 (ZIF-8) is a metal organic framework with exceptional intrinsic properties, high tunability, cost effectiveness, and producibility, which has boosted the research development of the field. ZIF-8-based materials have shown high capabilities for multiple purposes as catalysts, capacitors, electrodes, drug delivery systems, or adsorption/separation membranes. Herein, we report the synergistic combination of ZIF-8, plasmonic nanoparticles, and rationally designed protein adaptors and antibodies for fabricating novel surface-enhanced Raman scattering (SERS) tags with enhanced sensing capabilities. The SERS tags consist of Au@Ag core−shell nanorods individually encapsulated within a multifunctional ZIF-8 matrix encoded with Raman reporters. While the role of the plasmonic core is to enhance the Raman, the ZIF-8 traps the Raman active molecules and, more importantly, facilitates the active targeting of the SERS tag surface through the modular assembly with conventional (i.e., immunoglobulins) and recombinant antibodies (i.e., nanobodies) mediated by the specific interaction of Zn 2+ with polyhistidine-tagged protein G and SpyCatcher. Evidence of the capabilities of the Au@Ag@ZIF-8 nanotags for the SERS detection of EGFR and CD44 cell surface receptors in vitro illustrates the potential of these optical nanoprobes for imaging and multiplex biodetection. The reported modular assembly approach for the functionalization of ZIF-8 SERS nanotags with different classes of antibodies based on polyhistidinetagged peptides and protein−protein interactions can not only be applied to the ever-increasing number of reported MOFs structures but also can be further exploited as a universal means for the functionalization of other transition metal surfaces.

Plasmonic MOF Thin Films with Raman Internal Standard for Fast and Ultrasensitive SERS Detection of Chemical Warfare Agents in Ambient Air

“…Au@Ag@ZIF-8 nanoparticles consisting of a plasmonic core−shell Au@Ag nanorod coated with a ZIF-8 shell are obtained by CTAB-induced single encapsulation of the Au@Ag nanoparticles (81 ± 5 nm × 33 ± 2 nm; Figure S2 in the Supporting Information) within the MOF framework. 26,27 Figure 1A shows the representative TEM images of Au@Ag@ZIF-8 nanoparticles. The average Au@Ag@ZIF-8 nanoparticle size is 241 ± 25 nm with a ZIF-8 shell thickness of 90 ± 17 nm as determined from statistical analysis of TEM images (Figure S2C in the Supporting Information).…”

Plasmonic Nanoparticle-Metal–Organic Framework (NP–MOF) Nanohybrid Platforms for Emerging Plasmonic Applications

“…For instance, Raman-encoded Au@Ag@ZIF-8 nanoparticles have been designed to detect EGFR and CD44 proteins in mixed cell cultures. ZIF-8 serves a dual purpose of adsorbing the Raman probe close to the plasmonic Au@Ag nanorod core and as a bioconjugation site where the Zn 2+ can coordinate with polyhistidine …”

An Emerging Target in the Battle against Osteoarthritis: Macrophage Polarization

“…Zeolitic imidazolate framework-8 (ZIF-8) is a porous crystalline material formed by the coordination of zinc ions and 2-methylimidazole that has excellent biocompatibility. Therefore, ZIF-8 is considered to be an ideal carrier for controlling the transportation and release of medicine that has excellent potential in biomedicine applications [ 71 , 72 ].…”