Unniram, Ajmal

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Unniram
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Ajmal
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Unniram, Ajmal

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2022 - 20243

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    Publikation
    Exploring the potential of various cyclodextrin‐based derivatives in enzyme supramolecular engineering
    (Wiley, 28.11.2024) Foroutan Kalourazi, Ali; Nazemi, Amir; Unniram, Ajmal; Ferrer, Manuel; Shahangian, S. Shirin; Shahgaldian, Patrick
    Enzyme stability and activity are pivotal factors for their implementation in different industrial applications. Enzyme supramolecular engineering relies on the fabrication of a tailor-made enzyme nano-environment to ensure enzyme stability without impairing activity. Cyclodextrins (CDs), cyclic oligomers of glucose, act as protein chaperones and stabilize, upon interaction with hydrophobic amino acid residues exposed at the protein surface, its three-dimensional structure. When used to build an organosilica layer shielding an enzyme, they enhance the protective effect of this layer. In the present study, we systematically assessed the protective effects of three organosilane derivatives based on ɑ-, β- and γ-CDs. A model lipase enzyme was immobilized at the surface of silica nanoparticles and shielded in an organosilica layer containing these organosilanes. Besides layer thickness optimization, the effect of different stressors (i. e., temperature, SDS, urea) was tested. Our results showed that organosilica layers produced with CDs improve enzyme thermal stability. They also support enzyme refolding after denaturation under chaotic conditions. Additionally, we demonstrated that the protective effect of the smallest CD derivative tested, namely ɑ-CD, surpassed the other macrocycles studied for conferring the immobilized enzyme with higher resistance to stress conditions. This protection strategy was also applied to a thermostable β-galactosidase enzyme.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Atomically precise surface chemistry of zirconium and hafnium metal oxo clusters beyond carboxylate ligands
    (Royal Society of Chemistry, 2024) Unniram, Ajmal; Pokratath, Rohan; Parammal, Muhammed Jibin; Dhaene, Evert; Van den Eynden, Dietger; Balog, Sandor; Prescimone, Alessandro; Infante, Ivan; Shahgaldian, Patrick; De Roo, Jonathan
    The effectiveness of nanocrystals in many applications depends on their surface chemistry. Here, we leverage the atomically precise nature of zirconium and hafnium oxo clusters to gain fundamental insight into the thermodynamics of ligand binding. Through a combination of theoretical calculations and experimental spectroscopic techniques, we determine the interaction between the M6O88+ (M = Zr, Hf) cluster surface and various ligands: carboxylates, phosphonates, dialkylphosphinates, and monosubstituted phosphinates. We refute the common assumption that the adsorption energy of an adsorbate remains unaffected by the surrounding adsorbates. For example, dialkylphosphinic acids are too sterically hindered to yield complete ligand exchange, even though a single dialkylphosphinate has a high binding affinity. Monoalkyl or monoaryl phosphinic acids do replace carboxylates quantitatively and we obtained the crystal structure of M6O8H4(O2P(H)Ph)12 (M = Zr, Hf), giving insight into the binding mode of monosubstituted phosphinates. Phosphonic acids cause a partial structural reorganization of the metal oxo cluster into amorphous metal phosphonate as indicated by pair distribution function analysis. These results rationalize the absence of phosphonate-capped M6O8 clusters and the challenge in preparing Zr phosphonate metal–organic frameworks. We thus further reinforce the notion that monoalkylphosphinates are carboxylate mimics with superior binding affinity.
    01A - Beitrag in wissenschaftlicher Zeitschrift
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    Publikation
    Water-soluble optical sensors: keys to detect aluminium in biological environment
    (Royal Society of Chemistry, 01.01.2022) Unniram, Ajmal; Kavyashree, P.; Silswal, Akshay; Koner, Apurba Lal
    Metal ion plays a critical role from enzyme catalysis to cellular health and functions. The concentration of metal ions in a living system is highly regulated. Among the biologically relevant metal ions, the role and toxicity of aluminium in specific biological functions have been getting significant attention in recent years. The interaction of aluminium and the living system is unavoidable due to its high earth crust abundance, and the long-term exposure to aluminium can be fatal for life. The adverse Al3+ toxicity effects in humans result in various diseases ranging from cancers to neurogenetic disorders. Several Al3+ ions sensors have been developed over the past decades using the optical responses of synthesized molecules. However, only limited numbers of water-soluble optical sensors have been reported so far. In this review, we have confined our discussion to water-soluble Al3+ ions detection using optical methods and their utility for live-cell imaging and real-life application.
    01A - Beitrag in wissenschaftlicher Zeitschrift