Highlights

This work identifies a novel antibacterial mechanism that targets the cell wall of the human pathogen Streptococcus pneumoniae. Unlike conventional cell-wall targeting antibiotics, which inhibit the natural cross-linking of peptidoglycan, we introduce artificial cross-links using metabolic engineering to insert a clickable function into the other main component of the Gram-positive cell wall, the teichoic acids, then perform Strain-Promoted Alkyne-Azide Cycloaddition (SPAAC) and demonstrate that this results in impaired cell growth.

Due to their ability to bind aptamers in the free rather than in the target-bound folded state, single-stranded DNA-binding (SSB) proteins hold great promise in bioanalysis. SSB reagents are usually exploited through the target-induced displacement of aptamer pre-bound to the protein. However, the interaction strength between DNA molecules and SSB is intrinsically associated with lengthy desorption that (i) limits the range of application to oligonucleotides that do not associate too strongly with the protein and (ii) hampers the speed of the assays. Herein, we applied a very simple approach to solve this problem. Rather than working on the typical design of DNA displacement, we implemented pre-incubation of the target and aptamer before adding SSB to reveal the unbound aptamer fraction. We focused on the free-state unstructured anti-L-tyrosinamide (L-Ym) DNA aptamer, which was particularly relevant for the proof-of-concept study due to its potential to tightly bind to SSB with very slow off-rates. We considered fluorescence anisotropy (FA) for monitoring changes in the binding reactions of fluorescently labelled aptamer upon L-Ym addition. While no FA response was attainable under conventional displacement conditions, our approach enabled to generate substantial target-dependent FA signal in just 90 s. Under optimised conditions, we were able to achieve a detection threshold as low as 700 pM, which is the lowest ever documented for L-Ym in homogeneous-phase assays. We believe that the present scheme will enable SSB-based aptamer assays and sensors to greatly expand their scope of practical application.

The electrochemical reduction of CO2, coupled with renewable energy, offers a promising approach to convert CO2 to valuable products. A critical challenge for practical application is achieving O2 tolerance─the ability of the catalyst to sustain CO2 reduction without degradation in the presence of O2. This study highlights the self-protection mechanism of TPPFe in homogeneous electrocatalysis against O2 and reactive oxygen species (ROS). Using rotating disk voltammetry, constant potential electrolysis, and spectro-electrochemistry, we demonstrate that lesser reduced TPPFe states selectively reduce O2, form a protective layer that shields the active catalyst for CO2 reduction. This self-protection mechanism, applicable to other catalysts with multiple redox states and adaptable to molecular catalysts immobilized in thick films, underscores the importance of optimizing mass transport conditions and catalyst design to achieve an O2-tolerant CO2 reduction.

Ultrathin polypyrrole films were electropolymerized directly onto native or minimally treated silicon in a single step. Film thickness, morphology, and oxidation state were tuned by varying pretreatment, deposition and post-treatment conditions. The method supports localized electrospotting in microliter volumes for multiplexed biofunctionalization and could be adapted in the future to biosensing and micro/nanofluidics platforms needing surface functionality and charge control.

Nanostructured lipid carriers (NLCs) have emerged as a promising platform for drug delivery, offering advantages such as high drug-loading capacity and improved physicochemical stability. To enhance their targeting specificity, surface functionalization is crucial, as it enables selective interactions with biological receptors. In this study, we evaluated two distinct chemical strategies for the glycoengineering of NLCs. The grafting method proved superior, yielding glycosylated NLCs that were stable, biocompatible, and efficiently functionalized.

The effect of the substitution of a guanine base by the oxidative lesion 8-oxo-7,8-dihydroguanine (OG) on the affinity of the DNA aptamer selected against L-argininamide (L-Rm) was studied by fluorescence anisotropy. Results shown that, depending on the OG position, the substitution either reduces, does not affect or increases the affinity. Specific oxidation of the OG-containing aptamers by an Ir(IV) salt was carried out to promote crosslinks formation with the L-Rm target. Results shown that crosslinks occur with the OG-containing aptamers but also with scramble sequences not supposed to bind L-Rm. Efforts to reduce formation of such unspecific crosslinks were only partially successful, as they failed to demonstrate that part of these adducts originated from specific recognition of aptamers towards L-Rm.