Combinatorial Synthesis of Macromolecular Arrays by Microchannel Cantilever Spotting (µCS)

Surface‐bound microarrays of multiple oligo‐ and macromolecules (e.g., peptides, DNA) offer versatile options in biomedical applications like drug screening, DNA analysis, or medical diagnostics. Combinatorial syntheses of these molecules in situ can save significant resources in regard to processing time and material use. Furthermore, high feature densities are needed to enable high‐throughput and low sample volumes as generally regarded in combinatorial chemistry. Here, a scanning‐probe‐lithography‐based approach for the combinatorial in situ synthesis of macromolecules is presented in microarray format. Feature sizes below 40 µm allow for the creation of high‐density arrays with feature densities of 62 500 features per cm². To demonstrate feasibility of this approach for biomedical applications, a multiplexed array of functional protein tags (HA‐ and FLAG‐tag) is synthesized, and selective binding of respective epitope recognizing antibodies is shown. This approach uses only small amounts of base chemicals for synthesis and can be further parallelized, therefore, opening up a route to flexible, highly dense, and cost‐effective microarrays.     

Superior Stability and Emission Quantum Yield (23% ± 3%) of Single‐Layer 2D Tin Perovskite TEA2SnI4 via Thiocyanate Passivation

Tin‐based perovskite, which exhibits narrower bandgap and comparable photophysical properties to its lead analogs, is one of the most forward‐looking lead‐free semiconductor materials. However, the poor oxidative stability of tin perovskite hinders the development toward practical application. In this work, the effect of pseudohalide anions on the stability and emission properties of single‐layer 2D tin perovskite nanoplates with chemical formula TEA₂SnI₄ (TEA = 2‐thiophene‐ethylammonium) is reported. The results reveal that ammonium thiocyanate (NH₄SCN) is the most effective additive in enhancing the stability and photoluminescence quantum yield of 2D TEA₂SnI₄ (23 ± 3%). X‐Ray photoelectron spectroscopic investigations on the thiocyanate passivated TEA₂SnI₄ nanoplate show less than a 1% increase of Sn⁴⁺ signal upon 30 min exposure to air under ambient conditions (298 K, humidity ≈70%). Furthermore, no noticeable decrease in emission intensity of the nanoplate is observed after 20 h in air. The SCN^‐ passivation during the growth stage of TEA₂SnI₄ is proposed to play a crucial role in preventing the oxidation of Sn²⁺ and hence boosts both stability and photoluminescence yield of tin perovskite nanoplates.