This is a novel example of tailor-made design of hydrogels for anticancer drug release.

A dipeptide with a long fatty acid chain at its N-terminus gives hydrogels in phosphate buffer in the pH range 7.0–8.5. The hydrogel with a gelator concentration of 0.45% (w/v) at pH 7.46 (physiological pH) provides a very good platform to study dynamic changes within a supramolecular framework as it exhibits remarkable change in its appearance with time. Interestingly, the first formed transparent hydrogel gradually transforms into a turbid gel within 2 days. These two forms of the hydrogel have been thoroughly investigated by using small angle X-ray scattering (SAXS), powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FE-SEM) and high-resolution transmission electron microscopic (HR-TEM) imaging, FT-IR and rheometric analyses. The SAXS and low angle PXRD studies substantiate different packing arrangements for the gelator molecules for these two different gel states (the freshly prepared and the aged hydrogel). Moreover, rheological studies of these two gels reveal that the aged gel is stiffer than the freshly prepared gel.

Significance: Research on the chemical origin of life comprises one of the most exciting topics in contemporary science. Prebiotic chemistry provided evidence that precursors of both nucleic acids and proteins might be formed in the prebiotic environment. Yet, studies on nonenzymatic replication—a central mechanism driving chemical evolution—focused largely on each class of these molecules separately. This paper reveals a successful attempt to replicate simple nucleopeptide chimeras. Most importantly, different mechanisms control the replication of complementary chimeras, leading to a clear selection of one over the other. We propose that related processes may have led to the emergence of the first functional nucleic-acid–peptide assemblies, which further developed into biological assemblies such as the ribosomes and viruses.