We describe a microporous plasmonic nanoreactor to carry out designed near-infrared (NIR)-driven photothermal cyclizations inside living cells. As a proof of concept, we chose an intramolecular cyclization that is based on the nucleophilic attack of a pyridine onto an electrophilic carbon, a process that requires high activation energies and is typically achieved in bulk solution by heating at ∼90 °C. The core–shell nanoreactor (NR) has been designed to include a gold nanostar core, which is embedded within a metal–organic framework (MOF) based on a polymer-stabilized zeolitic imidazole framework-8 (ZIF-8). Once accumulated inside living cells, the MOF-based cloak of NRs allows an efficient diffusion of reactants into the plasmonic chamber, where they undergo the transformation upon near-IR illumination. The photothermal-driven reaction enables the intracellular generation of cyclic fluorescent products that can be tracked using fluorescence microscopy. The strategy may find different type of applications, such as for the spatio-temporal activation of prodrugsThe authors thank the financial support of the MCIN/AEI (PID2020-119206RB-I00, PID2019-108624RB-I00, CTQ2017-84767-P, RYC-2017-23457, RYC-2019-028238-I, RTI2018-093813-J-I00), the Xunta de Galicia (ED431F 2017/02, 2021-CP054, ED431C-2021/25, Centro Singular de Investigación de Galicia Accreditation 2019−2022, and ED431G 2019/03), the European Union (European Regional Development Fund − ERDF; H2020-MSCA-IF grant agreement no. 749667; H2020-MSCA-ITN grant agreement no. 860942; H2020-FET-Open grant agreement No. 899612; and INTERREG V-A Spain−Portugal, project 0624_2IQBIONEURO_6_E), and the European Research Council (starting grant no. 950421, advanced grant no. 340055). The support of the orfeo-cinqa network (CTQ2016-81797-REDC) is also kindly acknowledgedS
