Self-assembling behaviour of a modified aromatic amino acid in competitive medium

Soft Matter ◽  
2020 ◽  
Vol 16 (28) ◽  
pp. 6599-6607 ◽  
Author(s):  
Pijush Singh ◽  
Souvik Misra ◽  
Nayim Sepay ◽  
Sanjoy Mondal ◽  
Debes Ray ◽  
...  

The self-assembly and photophysical properties of 4-nitrophenylalanine (4NP) are changed with the alteration of solvent and final self-assembly state of 4NP in competitive solvent mixture and are dictated by the solvent ratio.

2021 ◽  
Author(s):  
Bharti Koshti ◽  
Ramesh Singh ◽  
Vivekshinh Kshtriya ◽  
Shanka Walia ◽  
Dhiraj Bhatia ◽  
...  

<p>.<br></p><p>The self-assembly of single amino acids is very important topic of research since there are plethora of diseases like phenylketonuria, tyrosinemia, hypertryptophanemia, hyperglycinemia, cystinuria and maple syrup urine disease to name a few which are caused by the accumulation or excess of amino acids. These are in-born errors of metabolisms (IEM’s) which are caused due to the deficiency of enzymes involved in catabolic pathways of these enzymes. Hence, it is very pertinent to understand the fate of these excess amino acids in the body and their self-assembling behaviour at molecular level. From the previous literature reports it may be surmised that the single amino acids like Phenylalanine, Tyrosine, Tryptophan, Cysteine and Methionine assemble to amyloid like structures, and hence have important implications in the pathophysiology of IEM’s like phenylketonuria, tyrosinemia, hypertryptophanemia, cystinuria and hypermethioninemia respectively. In this manuscript we report the self-assembly of lysine hydrocholride to fiber like structures in deionized water. It could be observed that lysine assemble to globular structures in fresh condition and then gradually changes to fiber like morphologies by self-association over time after 24 hours. These fibers gradually change to tubular morphologies after 3 day followed by fractal irregular morphologies in 10 and 15 days respectively. Notably, lysine exists as positively charged amino acid at physiological pH and the amine groups in lysine remain protonated. Hence, the self-assembling properties of lysine hydrochloride in deionized water is also pertinent and give insights into the fate of this amino acid in body in case it remains unmetabolized. Further, MTT assays were done to analyse the toxicities of these aggregates and the assay suggest their cytotoxic nature on SHSY5Y neural cell lines. Hence, the aggregation of lysine may be attributed to the pathological symptoms caused in diseases like hyperlysinemia which is associated with the neurological problems like seizures and short-term memory as observed in case of amyloid diseases like Parkinson’s and Alzheimer’s to name a few.</p>


ChemPhotoChem ◽  
2020 ◽  
Vol 4 (7) ◽  
pp. 481-486
Author(s):  
Mei‐Yu Yeh ◽  
Tzu‐Yu Tseng ◽  
Hui‐Chun Hsieh ◽  
Bao‐Xing Wu ◽  
Yi‐Shun Liao ◽  
...  

2021 ◽  
Author(s):  
Bharti Koshti ◽  
Ramesh Singh ◽  
Vivekshinh Kshtriya ◽  
Shanka Walia ◽  
Dhiraj Bhatia ◽  
...  

<p>.<br></p><p>The self-assembly of single amino acids is very important topic of research since there are plethora of diseases like phenylketonuria, tyrosinemia, hypertryptophanemia, hyperglycinemia, cystinuria and maple syrup urine disease to name a few which are caused by the accumulation or excess of amino acids. These are in-born errors of metabolisms (IEM’s) which are caused due to the deficiency of enzymes involved in catabolic pathways of these enzymes. Hence, it is very pertinent to understand the fate of these excess amino acids in the body and their self-assembling behaviour at molecular level. From the previous literature reports it may be surmised that the single amino acids like Phenylalanine, Tyrosine, Tryptophan, Cysteine and Methionine assemble to amyloid like structures, and hence have important implications in the pathophysiology of IEM’s like phenylketonuria, tyrosinemia, hypertryptophanemia, cystinuria and hypermethioninemia respectively. In this manuscript we report the self-assembly of lysine hydrocholride to fiber like structures in deionized water. It could be observed that lysine assemble to globular structures in fresh condition and then gradually changes to fiber like morphologies by self-association over time after 24 hours. These fibers gradually change to tubular morphologies after 3 day followed by fractal irregular morphologies in 10 and 15 days respectively. Notably, lysine exists as positively charged amino acid at physiological pH and the amine groups in lysine remain protonated. Hence, the self-assembling properties of lysine hydrochloride in deionized water is also pertinent and give insights into the fate of this amino acid in body in case it remains unmetabolized. Further, MTT assays were done to analyse the toxicities of these aggregates and the assay suggest their cytotoxic nature on SHSY5Y neural cell lines. Hence, the aggregation of lysine may be attributed to the pathological symptoms caused in diseases like hyperlysinemia which is associated with the neurological problems like seizures and short-term memory as observed in case of amyloid diseases like Parkinson’s and Alzheimer’s to name a few.</p>


2019 ◽  
Author(s):  
Nidhi Gour ◽  
Vivek Shinh Kshtriya ◽  
Shradhey Gupta ◽  
Ramesh, Singh ◽  
Dhawal Patel ◽  
...  

<p></p><p>We report self-assembly and photophysical properties of a new pyridothiazole based aggregation-induced-emission enhancement (AIEE) luminogen 4-(5-methoxy-thiazolo[4,5-b]pyridin-2-yl)benzoic acid (<b>PTC1</b>) and its application for the sensitive detection and monitoring of amyloid fibrillation. The self-assembling properties of the new AIEE probe are extensively studied by AFM and it was noted that as aggregation increases there is enhancement of fluorescence. The fluorescence of <b>PTC1 </b>is quenched upon addition of cupric (Cu<sup>2+</sup>) ions while the fluorescence is regenerated in the presence of amyloid fibers. AFM studies reveal that <b>PTC1</b> self associate/aggregate to hairy micelle structures which gets disrupted on the addition of Cu<sup>2+ </sup>and again reassembles in the presence of amyloid fibers. Hence, the fluorescence quenching and regeneration may be attributed to disaggregation and AIE respectively. Further, a comparative analysis of the performance of<b> PTC1</b> is done with the conventional ThT which confirms it to be a more sensitive probe for the detection of amyloid both in the presence and absence of Cu<sup>2+</sup>. Of note, a very simple, facile and cost-effective methodology for the detection of amyloid fibres is presented, wherein fluorescence quenching/enhancement can be visualized under UV without the use of sophisticated instrumentation techniques. To the best of our knowledge and literature survey, this is first report wherein the self-assembling properties of AIEE probe is studied extensively via microscopy and the photophysical properties compared w.r.t to the morphological transformations. The AIEE probe has been designed using an unusual pyridothiazole scaffold unlike the commonly used archetypal AIE scaffolds based on tetraphenylethene (TPE) and hexaphenylsilole (HPS) and hence, the work also has implications in designing new generation AIEE dyes based on novel scaffold reported. </p><br><p></p>


2016 ◽  
Vol 40 (6) ◽  
pp. 5568-5576 ◽  
Author(s):  
Yimeng Zhang ◽  
Shangyang Li ◽  
Mingfang Ma ◽  
Minmin Yang ◽  
Yajie Wang ◽  
...  

The self-assembly of an aromatic amino acid affords diverse aggregates from flat nanofibers to twist nanofibers with tunable supramolecular chirality.


2019 ◽  
Author(s):  
Nidhi Gour ◽  
Vivek Shinh Kshtriya ◽  
Shradhey Gupta ◽  
Ramesh, Singh ◽  
Dhawal Patel ◽  
...  

<p></p><p>We report self-assembly and photophysical properties of a new pyridothiazole based aggregation-induced-emission enhancement (AIEE) luminogen 4-(5-methoxy-thiazolo[4,5-b]pyridin-2-yl)benzoic acid (<b>PTC1</b>) and its application for the sensitive detection and monitoring of amyloid fibrillation. The self-assembling properties of the new AIEE probe are extensively studied by AFM and it was noted that as aggregation increases there is enhancement of fluorescence. The fluorescence of <b>PTC1 </b>is quenched upon addition of cupric (Cu<sup>2+</sup>) ions while the fluorescence is regenerated in the presence of amyloid fibers. AFM studies reveal that <b>PTC1</b> self associate/aggregate to hairy micelle structures which gets disrupted on the addition of Cu<sup>2+ </sup>and again reassembles in the presence of amyloid fibers. Hence, the fluorescence quenching and regeneration may be attributed to disaggregation and AIE respectively. Further, a comparative analysis of the performance of<b> PTC1</b> is done with the conventional ThT which confirms it to be a more sensitive probe for the detection of amyloid both in the presence and absence of Cu<sup>2+</sup>. Of note, a very simple, facile and cost-effective methodology for the detection of amyloid fibres is presented, wherein fluorescence quenching/enhancement can be visualized under UV without the use of sophisticated instrumentation techniques. To the best of our knowledge and literature survey, this is first report wherein the self-assembling properties of AIEE probe is studied extensively via microscopy and the photophysical properties compared w.r.t to the morphological transformations. The AIEE probe has been designed using an unusual pyridothiazole scaffold unlike the commonly used archetypal AIE scaffolds based on tetraphenylethene (TPE) and hexaphenylsilole (HPS) and hence, the work also has implications in designing new generation AIEE dyes based on novel scaffold reported. </p><br><p></p>


2020 ◽  
Vol 27 (9) ◽  
pp. 923-929
Author(s):  
Gaurav Pandey ◽  
Prem Prakash Das ◽  
Vibin Ramakrishnan

Background: RADA-4 (Ac-RADARADARADARADA-NH2) is the most extensively studied and marketed self-assembling peptide, forming hydrogel, used to create defined threedimensional microenvironments for cell culture applications. Objectives: In this work, we use various biophysical techniques to investigate the length dependency of RADA aggregation and assembly. Methods: We synthesized a series of RADA-N peptides, N ranging from 1 to 4, resulting in four peptides having 4, 8, 12, and 16 amino acids in their sequence. Through a combination of various biophysical methods including thioflavin T fluorescence assay, static right angle light scattering assay, Dynamic Light Scattering (DLS), electron microscopy, CD, and IR spectroscopy, we have examined the role of chain-length on the self-assembly of RADA peptide. Results: Our observations show that the aggregation of ionic, charge-complementary RADA motifcontaining peptides is length-dependent, with N less than 3 are not forming spontaneous selfassemblies. Conclusion: The six biophysical experiments discussed in this paper validate the significance of chain-length on the epitaxial growth of RADA peptide self-assembly.


2021 ◽  
Vol 22 (17) ◽  
pp. 9634
Author(s):  
Moran Aviv ◽  
Dana Cohen-Gerassi ◽  
Asuka A. Orr ◽  
Rajkumar Misra ◽  
Zohar A. Arnon ◽  
...  

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling. A minimal alteration of the chemical environment could cause a significant impact. In this context, we report the effects of modifying the position of a single atom on the properties and kinetics of the self-assembly process. A combination of experimental and computational methods, used to investigate double-fluorinated Fmoc-Phe derivatives, Fmoc-3,4F-Phe and Fmoc-3,5F-Phe, reveals the unique effects of modifying the position of a single fluorine on the self-assembly process, and the physical properties of the product. The presence of significant physical and morphological differences between the two derivatives was verified by molecular-dynamics simulations. Analysis of the spontaneous phase-transition of both building blocks, as well as crystal X-ray diffraction to determine the molecular structure of Fmoc-3,4F-Phe, are in good agreement with known changes in the Phe fluorination pattern and highlight the effect of a single atom position on the self-assembly process. These findings prove that fluorination is an effective strategy to influence supramolecular organization on the nanoscale. Moreover, we believe that a deep understanding of the self-assembly process may provide fundamental insights that will facilitate the development of optimal amino-acid-based low-molecular-weight hydrogelators for a wide range of applications.


Nanoscale ◽  
2019 ◽  
Vol 11 (34) ◽  
pp. 15917-15928 ◽  
Author(s):  
Emily R. Draper ◽  
Liam Wilbraham ◽  
Dave J. Adams ◽  
Matthew Wallace ◽  
Ralf Schweins ◽  
...  

We use a combination of computational and experimental techniques to study the self-assembly and gelation of amino-acid functionalised water-soluble perylene bisimides.


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