https://libjncir.jncasr.ac.in/xmlui/handle/10572/1486 2026-04-04T05:31:45Z https://libjncir.jncasr.ac.in/xmlui/handle/10572/2488 Nanoarchitectonics of biomolecular assemblies for functional applications Avinash, M. B.; Govindaraju, T. The stringent processes of natural selection and evolution have enabled extraordinary structure function properties of biomolecules. Specifically, the archetypal designs of biomolecules, such as amino acids, nucleobases, carbohydrates and lipids amongst others, encode unparalleled information, selectivity and specificity. The integration of biomolecules either with functional Molecules or with an embodied functionality ensures an eclectic approach for novel and advanced nanotechnological applications ranging from electronics to biomedicine, besides bright prospects in systems chemistry and synthetic biology. Given this intriguing scenario, our feature article intends to shed light on the emerging field of functional biomolecular engineering. Restricted Access 2014-01-01T00:00:00Z https://libjncir.jncasr.ac.in/xmlui/handle/10572/2489 Synthesis of Hybrid Cyclic Peptoids and Identification of Autophagy Enhancer Rajasekhar, Kolla; Narayanaswamy, Nagarjun; Mishra, Piyush; Suresh, S. N.; Manjithaya, Ravi; Govindaraju, T. Cyclic peptoids are potential candidates for diverse biological activities. However, applications of cyclic peptoids are limited by the synthetic difficulties, conformational flexibility of large cyclic peptoids, and lack of secondary amide in the backbone. Herein, an elegant methodology for the synthesis of small and medium-size cyclic hybrid peptoids is developed. N-alpha-Alkyl and N-alpha-acyl substituents in N-(2-aminoethyl) glycine monomers enforce intra-and intermolecular cyclization to form stable six-and 12-membered cyclic products, respectively. NMR studies show inter-and intramolecular hydrogen bonding in six-and 12-membered cyclic peptoids, respectively. Screening of a cyclic peptoid library resulted in the identification of a potential candidate that enhanced autophagic degradation of cargo in a live cell model. Such upregulation of autophagy using small molecules is a promising approach for elimination of intracellular pathogens and neurodegenerative protein aggregates. Restricted Access 2014-01-01T00:00:00Z https://libjncir.jncasr.ac.in/xmlui/handle/10572/2487 Biomimetic molecular organization of naphthalene diimide in the solid state: tunable (chiro-) optical, viscoelastic and nanoscale properties Pandeeswar, M.; Khare, Harshavardhan; Ramakumar, Suryanarayanarao; Govindaraju, T. The interfacing of aromatic molecules with biomolecules to design functional molecular materials is a promising area of research. Intermolecular interactions determine the performance of these materials and therefore, precise control over the molecular organization is necessary to improve functional properties. Herein we describe the tunable biomimetic molecular engineering of a promising n-type organic semiconductor, naphthalene diimide (NDI), in the solid state by introducing minute structural mutations in the form of amino acids with variable Ca-functionality. For the first time we could achieve all four possible crystal packing modes, namely cofacial, brickwork, herringbone and slipped stacks of the NDI system. Furthermore, amino acid conjugated NDIs exhibit ultrasonication induced organogels with tunable visco-elastic and temperature responsive emission properties. The amino acid-NDI conjugates self-assemble into 0D nanospheres and 1D nanofibers in their gel state while the ethylamine-NDI conjugate forms 2D sheets from its solution. Photophysical studies indicated the remarkable influence of molecular ordering on the absorption and fluorescence properties of NDIs. Interestingly, the circular dichroism (CD) and X-ray diffraction (XRD) studies revealed the existence of helical ordering of NDIs in both solution and solid state. The chiral amino acids and their conformations with respect to the central NDI core are found to influence the nature of the helical organization of NDIs. Consequently, the origin of the preferential handedness in the helical organization is attributed to transcription of chiral information from the amino acid to the NDI core. On account of these unique properties, the materials derived from NDI-conjugates might find a wide range of future interdisciplinary applications from materials to biomedicine. Restricted Access 2014-01-01T00:00:00Z https://libjncir.jncasr.ac.in/xmlui/handle/10572/2486 Assembly Modulation of PDI Derivative as a Supramolecular Fluorescence Switching Probe for Detection of Cationic Surfactant and Metal Ions in Aqueous Media Dwivedi, Atul K.; Pandeeswar, M.; Govindaraju, T. We report an amphiphilic perylene diimide (1), a bimolecular analog of L-3,4-dihydroxyphenylalanine (L-DOPA), as a reversible fluorescence switching probe for the detection and sensing of cationic surfactants and Fe3+/Cu2+ in an aqueous media respectively by means of host-guest interactions driven assembly and disassembly of 1. Photophysical studies of 1, going from dimethyl sulfoxide (DMSO) (State-I) to pure aqueous medium (State-II), suggested the formation of self-assembled aggregates by displaying very weak fluorescence emission along with red shifted broad absorption bands. Interestingly, the cationic surfactant cetyltrimethylammonium bromide (CTAB) could disassemble 1 in miceller conditions by restoring bright yellow fluorescence and vibronically well-defined (Franck-Condon progressions A(0-0)/A(0-1) approximate to 1.6) absorption bands of 1 over other neutral and anionic surfactants (State-III). Owing to the metal chelating nature of L-DOPA, 1 was able to sense Fe3+ and Cu2+ among a pool of other metal ions by means of fluorescence switching off state, attributed to metal interaction driven assembly of 1 (State-IV). Such metallosupramolecular assemblies were found to reverse back to the fluorescence switching on state using a metal ion chelator, diethylenetriaminepentaacetic acid (DTPA, State-III), further signifying the role of metal ions toward assembly of 1. Formation of assembly and disassembly could be visualized by the diminished and increased yellow emission under green laser light. Further, the assembly-disassembly modulation of 1 has been extensively characterized using infrared (IR), mass spectrometry, microscopy and dynamic light scattering (DLS) techniques. Therefore, modulation of the molecular self-assembly of PDI derivative 1 in aqueous media (assembled state, State-II) by means of host-guest interactions provided by micellar structures of CTAB (disassembled state, State-III), metal ion (Fe3+ and Cu2+) interactions (assembled state, State-IV) and metal ion sequestration using DTPA (disassembled state, State-III) is viewed as a supramolecular reversible fluorescence switching off-on probe for cationic surfactant CTAB and Fe3+/Cu2+. Restricted Access 2014-01-01T00:00:00Z