Due to its slow degradation rate, polycaprolactone (PCL) is frequently used in biomedical applications. This study deals with the development of antibacterial nanofibers based on PCL and halloysite nanotubes (HNTs). Thanks to a combination with HNTs, the prepared nanofibers can be used as low-cost nanocontainers for the encapsulation of a wide variety of substances, including drugs, enzymes, and DNA. In our work, HNTs were used as a nanocarrier for erythromycin (ERY) as a model antibacterial active compound with a wide range of antibacterial activity. Nanofibers based on PCL and HNT/ERY were prepared by electrospinning. The antibacterial activity was evaluated as a sterile zone of inhibition around the PCL nanofibers containing 7.0 wt.% HNT/ERY. The morphology was observed with SEM and TEM. The efficiency of HNT/ERY loading was evaluated with thermogravimetric analysis. It was found that the nanofibers exhibited outstanding antibacterial properties and inhibited both Gram- (Escherichia coli) and Gram+ (Staphylococcus aureus) bacteria. Moreover, a significant enhancement of mechanical properties was achieved. The potential uses of antibacterial, environmentally friendly, nontoxic, biodegradable PCL/HNT/ERY nanofiber materials are mainly in tissue engineering, wound healing, the prevention of bacterial infections, and other biomedical applications.

A series of 12 analogues of the Cer transfer protein (CERT) antagonist HPA‐12 with long aliphatic chains were prepared as their (1R,3S)‐syn and (1R,3R)‐anti stereoisomers from pivotal chiral oxoamino acids. The enantioselective access to these intermediates as well as their ensuing transformation relied on a practical crystallization‐induced asymmetric transformation (CIAT) process. Sonogashira coupling followed by triple bond reduction and thiophene ring hydrodesulfurization (HDS) into the corresponding alkane moieties was then implemented to complete the synthetic routes delivering the targeted HPA‐12 analogues in concise 4‐ to 6‐step reaction sequences. Ten compounds were evaluated regarding their ability to bind to the CERT START domain by using the recently developed time‐resolved FRET‐based homogeneous (HTR‐FRET) binding assay. The introduction of a lipophilic appendage on the phenyl moiety led to an overall 10‐ to 1000‐fold enhancement of the protein binding, with the highest effect being observed for a n‐hexyl residue in the meta position. The importance of the phenyl ring for the activity was indicated by the reduced potency of the 3‐deoxyphytoceramide aliphatic analogues. The 1,3‐syn stereoisomers were systematically more potent than their 1,3‐anti analogues. In silico studies were used to rationalized these trends, leading to a model of protein recognition coherent with the stronger binding of (1R,3S)‐syn HPAs.

Diastereoselective aza-Michael additions of phenylethylamine to 3-aroylbutenoic acids are reported. During these processes, efficient control over two new stereogenic centers on the Michael acceptor has been possible via crystallization-induced asymmetric transformation (CIAT). As an application, a convenient two-step synthesis of anti-β-methylhomophenylalanines is also described.