Colorimetric response and lipoplex formation with DNA of a high sensitive amine oxide substituted polydiacetylene

Utilization of chromic polydiacetylene assemblies as a platform to probe specific binding between drug and RNA

Recognition of nucleic acids remains an important endeavor in biology. Nucleic acids adopt shapes ranging from A-form (RNA and GC rich DNA) to B-form (AT rich DNA). We show, in this contribution, shape-specific recognition of A-U rich RNA duplex by a neomycin (Neo)-polydiacetylene (PDA) complex. PDA assemblies are fabricated by using a well-known diacetylene (DA) monomer, 10,12-pentacosadiynoic acid (PCDA). The response of poly(PCDA) assemblies is generated by mixing with a modified neomycin-PCDA monomer (Neo-PCDA). The functionalization by neomycin moiety provides specific binding with homopolyribonucleotide poly (rA) - poly (rU) stimulus. Various types of alcohols are utilized as additives to enhance the sensitivity of poly(PCDA)/Neo-PCDA assemblies. A change of absorption spectra is clearly observed when a relatively low concentration of poly (rA)-poly (rU) is added into the system. Furthermore, poly(PCDA)/Neo-PCDA shows a clear specificity for poly (rA)-poly (rU) over the corresponding DNA duplex. The variation of linker between neomycin moiety and conjugated PDA backbone is found to significantly affect its sensitivity. We also investigate other parameters including the concentration of Neo-PCDA and the DA monomer structure. Our results provide here preliminary data for an alternative approach to improve the sensitivity of PDA utilized in biosensing and diagnostic applications.

Polydiacetylene/triblock copolymer nanoblend applied as a sensor for micellar casein: A thermodynamic approach

Polydiacetylene (PDA) and triblock copolymer nanoblends were synthesized to detect micellar casein (MC), the main milk protein and an indicator of milk quality. UV-Vis spectrum showed that MC induced blue-to-red transition in nanoblends. When nanoblends and MC were separated by dialysis membrane colorimetric response (CR) was similar, whereas a remarkable CR reduction was noticed after addition of dialyzed-MC, suggesting that small molecules present in MC (salts) caused PDA color change. Interaction enthalpy variation between nanoblends and MC showed an abrupt increase that coincided with MC concentration when colorimetric transition occurred. Copolymer hydrophobic/hydrophilic balance and presence of other molecules in the system affected nanoblends CR. MC salts were found to interact with nanoblends leading to color changes. MC concentration, MC salt release, copolymer hydrophobic/hydrophilic balance, and presence of other molecules in the system affected responses of the sensors. These results contribute to future applications of PDA/copolymer nanosensors to dairy models.

Supramolecular gels from lipopeptide gelators: template improvement and strategies for the in-situ preparation of inorganic nanomaterials and for the dispersion of carbon nanomaterials

Lipopeptide amphiphiles are an important class of biobased and biomimetic surfactants that are easily prepared from the cheapest organic reagents, such as natural fatty and amino acids, and in many cases, the resulting compounds are able to harden not only common organic solvents but also waxes, water and ionic liquids. Well-tailored, these gelators can be selective for one variety of liquid, which leads to the formation of a robust gel that is able to incorporate various different elements. In this review, we attempted to provide our opinion regarding the molecular design of the lipopeptide gelator candidates. In addition, we summarized each type of element that is necessary for creating potent supramolecular gel templates that are useful for inorganic nano- and micro-material preparation. This review is not only limited to recent papers found in the literature; a portion of our unpublished results are also provided as a supplement to illustrate our point of view regarding this subject.