The fabrication of metal-organic framework (MOF) films on conducting substrates has demonstrated great potential in applications such as electronic conduction and sensing. For these applications, direct contact of the film to the conducting substrate without a self-assembled monolayer (SAM) is a desired step that must be achieved prior to the use of MOF films. In this report, we propose an in situ strategy for the rapid one-step conversion of Cu metal into HKUST-1 films on conducting Cu substrates. The Cu substrate acts both as a conducting substrate and a source of Cu ions during the synthesis of HKUST-1. This synthesis is possible because of the simultaneous reaction of an oxidizing agent and a deprotonating agent, in which the former agent dissolves the metal substrate to form Cu ions while the latter agent deprotonates the ligand. Using this strategy, the HKUST-1 film could not only be rapidly synthesized within 5 min but also be directly attached to the Cu substrate. Based on microscopic studies, we propose a plausible mechanism for the growth reaction. Furthermore, we show the versatility of this in situ conversion methodology, applying it to ZIF-8, which comprises Zn ions and imidazole-based ligands. Using an I-filled HKUST-1 film, we further demonstrate that the direct contact of the MOF film to the conducting substrate makes the material more suitable for use as a sensor or electronic conductor.

The manipulation of superparamagnetic beads has attracted various lab on a chip and magnetic tweezer platforms for separating, sorting, and labeling cells and bioentities, but the irreversible aggregation of beads owing to magnetic interactions has limited its actual functionality. Here, an efficient solution is developed for the disaggregation of magnetic beads and interparticle distance control with a magnetophoretic decoupler using an external rotating magnetic field. A unique magnetic potential energy distribution in the form of an asymmetric magnetic thin film around the gap is created and tuned in a controlled manner, regulated by the size ratio of the bead with a magnetic pattern. Hence, the aggregated beads are detached into single beads and transported in one direction in an array pattern. Furthermore, the simultaneous and accurate spacing control of multiple magnetic bead pairs is performed by adjusting the angle of the rotating magnetic field, which continuously changes the energy well associated with a specific shape of the magnetic patterns. This technique offers an advanced solution for the disaggregation and controlled manipulation of beads, can allow new possibilities for the enhanced functioning of lab on a chip and magnetic tweezers platforms for biological assays, intercellular interactions, and magnetic biochip systems.

Cell clustering techniques are important to produce artificial cell clusters for in vitro models of intercellular mechanisms at the single‐cell level. The analyses considering physical variables such as the shape and size of cells have been very limited. In addition, the precise manipulation of cells and control of the physical variables are still challenging. In this paper, a magnetophoretic device consisting of a trampoline micromagnet and active elements that enable the control of individual selective jumping motion and positioning of a micro‐object is proposed. Based on a numerical simulation under various conditions, automatic separation or selective clustering of micro‐objects according to their sizes is performed by parallel control and programmable manipulation. This method provides efficient control of the physical variables of cells and grouping of cells with the desired size and number, which can be a milestone for a better understanding of the intercellular dynamics between clustered cells at the single‐cell level for future cell‐on‐chip applications.

No abstract

Magnetophoretic Micro‐Distributor In article number 2103579, Byeonghwa Lim, CheolGi Kim, and co‐workers propose a magnetophoretic device which consists of a trampoline micromagnet and active elements which enable the control of individual cell‐based on physical variables for the automatic separation or selective clustering for intercellular communications. This technology could be a milestone for a better understanding of the intercellular dynamics between clustered cells at the single‐cell level for future cell‐on‐chip applications.