scholarly journals Toward Chemotactic Supramolecular Nanoparticles: From Autonomous Surface Motion Following Specific Chemical Gradients to Multivalency-Controlled Disassembly

ACS Nano ◽  
2021 ◽  
Author(s):  
Chiara Lionello ◽  
Andrea Gardin ◽  
Annalisa Cardellini ◽  
Davide Bochicchio ◽  
Manisha Shivrayan ◽  
...  
Keyword(s):  
Specific Chemical ◽  
Surface Motion ◽  
Chemical Gradients ◽  
Supramolecular Nanoparticles

scholarly journals Towards Chemotactic Supramolecular Nanoparticles: From Autonomous Surface Motion Following Specific Chemical Gradients to Multivalency-Controlled Disassembly

2021 ◽  
Author(s):  
Chiara Lionello ◽  
Andrea Gardin ◽  
Annalisa Cardellini ◽  
Davide Bochicchio ◽  
Manisha Shivrayan ◽  
...  
Keyword(s):  
Critical Concentration ◽  
Surface Group ◽  
Point Of View ◽  
Coarse Grained ◽  
Specific Chemical ◽  
Chemical Surface ◽  
Chemical Gradients ◽  
Molecular Features ◽  
Self Assembled ◽  
Multivalent Interactions

<p>Nature designs chemotactic supramolecular structures that can selectively bind specific groups present on surfaces, autonomously scan them moving along density gradients, and react once a critical concentration is encountered. While such properties are key in many biological functions, these also offer inspirations for designing artificial systems capable of similar bioinspired autonomous behaviors. One approach is to use soft molecular units that self-assemble in aqueous solution generating nanoparticles (NPs) that display specific chemical groups on their surface, enabling for multivalent interactions with complementarily functionalized surfaces. However, a first challenge is to explore the behavior of these assemblies at sufficiently high-resolution to gain insights on the molecular factors controlling their behaviors. Here we show that, coupling coarse-grained molecular models and advanced simulation approaches, it is possible to study the (autonomous or driven) motion of self-assembled NPs on a receptor-grafted surface at submolecular resolution. As an example, we focus on self-assembled NPs composed of facially amphiphilic oligomers. We observe how tuning the multivalent interactions between the NP and the surface allows to control NP binding, its diffusion along chemical surface gradients, and ultimately, the NP reactivity at determined surface group densities. <i>In silico</i> experiments provide physical-chemical insights on key molecular features in the self-assembling units which determine the dynamic behavior and fate of the NPs on the surface: from adhesion, to diffusion, and disassembly. This offers a privileged point of view into the chemotactic properties of supramolecular assemblies, improving our knowledge on how to design new types of materials with bioinspired autonomous behaviors.</p>

scholarly journals Towards Chemotactic Supramolecular Nanoparticles: From Autonomous Surface Motion Following Specific Chemical Gradients to Multivalency-Controlled Disassembly

2021 ◽  
Author(s):  
Chiara Lionello ◽  
Andrea Gardin ◽  
Annalisa Cardellini ◽  
Davide Bochicchio ◽  
Manisha Shivrayan ◽  
...  
Keyword(s):  
Critical Concentration ◽  
Surface Group ◽  
Point Of View ◽  
Coarse Grained ◽  
Specific Chemical ◽  
Chemical Surface ◽  
Chemical Gradients ◽  
Molecular Features ◽  
Self Assembled ◽  
Multivalent Interactions

<p>Nature designs chemotactic supramolecular structures that can selectively bind specific groups present on surfaces, autonomously scan them moving along density gradients, and react once a critical concentration is encountered. While such properties are key in many biological functions, these also offer inspirations for designing artificial systems capable of similar bioinspired autonomous behaviors. One approach is to use soft molecular units that self-assemble in aqueous solution generating nanoparticles (NPs) that display specific chemical groups on their surface, enabling for multivalent interactions with complementarily functionalized surfaces. However, a first challenge is to explore the behavior of these assemblies at sufficiently high-resolution to gain insights on the molecular factors controlling their behaviors. Here we show that, coupling coarse-grained molecular models and advanced simulation approaches, it is possible to study the (autonomous or driven) motion of self-assembled NPs on a receptor-grafted surface at submolecular resolution. As an example, we focus on self-assembled NPs composed of facially amphiphilic oligomers. We observe how tuning the multivalent interactions between the NP and the surface allows to control NP binding, its diffusion along chemical surface gradients, and ultimately, the NP reactivity at determined surface group densities. <i>In silico</i> experiments provide physical-chemical insights on key molecular features in the self-assembling units which determine the dynamic behavior and fate of the NPs on the surface: from adhesion, to diffusion, and disassembly. This offers a privileged point of view into the chemotactic properties of supramolecular assemblies, improving our knowledge on how to design new types of materials with bioinspired autonomous behaviors.</p>

Single Cell Based Microelectrode Array Biosensors

2003 ◽  
Vol 773 ◽  
Author(s):  
Mo Yang ◽  
Shalini Prasad ◽  
Xuan Zhang ◽  
Mihrimah Ozkan ◽  
Cengiz S. Ozkan
Keyword(s):  
Electrical Activity ◽  
Single Cell ◽  
Cellular Response ◽  
Microelectrode Array ◽  
Fast Fourier Transformation ◽  
Chemical Agent ◽  
Extracellular Potential ◽  
Membrane Excitability ◽  
Specific Chemical ◽  
Chemical Agents

AbstractExtracellular potential is an important parameter which indicates the electrical activity of live cells. Membrane excitability in osteoblasts plays a key role in modulating the electrical activity in the presence of chemical agents. The complexity of cell signal makes interpretation of the cellular response to a chemical agent very difficult. By analyzing shifts in the signal power spectrum, it is possible to determine a frequency spectrum also known as Signature Pattern Vectors (SPV) specific to a chemical. It is also essential to characterize single cell sensitivity and response time for specific chemical agents for developing detect-to-warn biosensors. We used a 4x4 multiple Pt microelectrode array to spatially position single osteoblast cells, by using a gradient AC field. Fast Fourier Transformation (FFT) and Wavelet Transformation (WT) analyses were used to extract information pertaining to the frequency of firing from the extracellular potential.

Polypeptides Folding: Rules for the Calculation of the Backbone Dihedral Angles φ starting from the Amino Acid Sequence

2020 ◽  
Author(s):  
Michele Larocca
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Theoretical Approach ◽  
Polypeptide Chain ◽  
Hydrophobic Effect ◽  
Side Chain ◽  
Dihedral Angles ◽  
Mechanical Forces ◽  
Specific Chemical

<p>Protein folding is strictly related to the determination of the backbone dihedral angles and depends on the information contained in the amino acid sequence as well as on the hydrophobic effect. To date, the type of information embedded in the amino acid sequence has not yet been revealed. The present study deals with these problematics and aims to furnish a possible explanation of the information contained in the amino acid sequence, showing and reporting rules to calculate the backbone dihedral angles φ. The study is based on the development of mechanical forces once specific chemical interactions are established among the side chain of the residues in a polypeptide chain. It aims to furnish a theoretical approach to predict backbone dihedral angles which, in the future, may be applied to computational developments focused on the prediction of polypeptide structures.</p>

Cell-Specific Chemical Delivery Using a Selective Nitroreductase–Nitroaryl Pair

2018 ◽  
Author(s):  
Todd D. Gruber ◽  
Chithra Krishnamurthy ◽  
Jonathan B. Grimm ◽  
Michael R. Tadross ◽  
Laura M. Wysocki ◽  
...  
Keyword(s):  
Small Molecules ◽  
Mammalian Cells ◽  
Target Cells ◽  
Specific Chemical ◽  
E Coli ◽  
Enzyme Substrate ◽  
Cell Specificity ◽  
General Chemical ◽  
Increased Activity ◽  
Enzyme Variant

<p>The utility of<b> </b>small molecules to probe or perturb biological systems is limited by the lack of cell-specificity. ‘Masking’ the activity of small molecules using a general chemical modification and ‘unmasking’ it only within target cells could overcome this limitation. To this end, we have developed a selective enzyme–substrate pair consisting of engineered variants of <i>E. coli</i> nitroreductase (NTR) and a 2‑nitro-<i>N</i>-methylimidazolyl (NM) masking group. To discover and optimize this NTR–NM system, we synthesized a series of fluorogenic substrates containing different nitroaromatic masking groups, confirmed their stability in cells, and identified the best substrate for NTR. We then engineered the enzyme for improved activity in mammalian cells, ultimately yielding an enzyme variant (enhanced NTR, or eNTR) that possesses up to 100-fold increased activity over wild-type NTR. These improved NTR enzymes combined with the optimal NM masking group enable rapid, selective unmasking of dyes, indicators, and drugs to genetically defined populations of cells.</p>

Reactive Nanopattern in a Triple Structured Bio-Inspired Honeycomb Film as a Clickable Platform

2018 ◽  
Author(s):  
Pierre Marcasuzaa ◽  
Samuel Pearson ◽  
Karell Bosson ◽  
Laurence Pessoni ◽  
Jean-Charles Dupin ◽  
...  
Keyword(s):  
Self Assembly ◽  
Double Porosity ◽  
Surface Groups ◽  
Specific Chemical ◽  
Site Specific ◽  
Surface Functionality ◽  
Wenzel State ◽  
Breath Figure ◽  
Responsive Surfaces ◽  
Secondary Population

A hierarchically structured platform was obtained from spontaneous self-assembly of a poly(styrene)-<i>b</i>-poly(vinylbenzylchloride) (PS-<i>b</i>-PVBC) block copolymer (BCP) during breath figure (BF) templating. The BF process using a water/ethanol atmosphere gave a unique double porosity in which hexagonally arranged micron-sized pores were encircled by a secondary population of smaller, nano-sized pores. A third level of structuration was simultaneously introduced between the pores by directed BCP self-assembly to form out-of-the-plane nano-cylinders, offering very rapid bottom-up access to a film with unprecedented triple structure which could be used as a reactive platform for introducing further surface functionality. The surface nano-domains of VBC were exploited as reactive nano-patterns for site-specific chemical functionalization by firstly substituting the exposed chlorine moiety with azide, then “clicking” an alkyne by copper (I) catalyzed azide-alkyne Huisgen cycloaddition (CuAAC). Successful chemical modification was verified by NMR spectroscopy, FTIR spectroscopy, and XPS, with retention of the micro- and nanostructuration confirmed by SEM and AFM respectively. Protonation of the cyclotriazole surface groups triggered a switch in macroscopic behavior from a Cassie-Baxter state to a Wenzel state, highlighting the possibility of producing responsive surfaces with hierarchical structure.

The Effect of Odor and Color on Chemical Cooling

2019 ◽  
Author(s):  
Robert Pellegrino ◽  
Curtis Luckett
Keyword(s):  
Primary Component ◽  
Magnitude Scale ◽  
Trigeminal System ◽  
Abstract Concepts ◽  
Specific Chemical ◽  
Chemical Binding ◽  
Cooling Intensity ◽  
Crossmodal Associations ◽  
First Session

Chemesthesis, along with taste and olfaction, is a primary component of flavor that engages the trigeminal system through specific chemical binding. For instance, many gums or confectionaries incorporate chemical cooling agents, such as Wilkinson Sword (WS) compounds, to create the sensation of coldness. The current study was designed to evaluate crossmodal associations of color and aroma with the chemesthetic perception of cooling. A “minty” and non-odorized set of confectionary stimuli, colored green, blue or white, with moderate cooling properties (with WS-3) were used in this study. In the first session, participants were randomly presented a stimuli and asked to rate several attributes including its cooling intensity on a generalized Labeled Magnitude Scale (gLMS). In the second session, the same participants were asked to relate cooling levels to different colors and which color relates to the “minty” odor. Additionally, open-ended reasons were given for association choices. Appearance and odor influenced the intensity of cooling sensation. In particular, the odorized and blue samples were rated as cooler than the non-odorized and other colored samples, respectively. The follow-up session confirms blue as a color associated with cooling properties, especially cool objects/abstract concepts. Meanwhile, odor’s enhancement on cooling sensation may be more perceptual in nature through affective matching from enhanced flavor.

Development of Peptides that Inhibit Aminoglycoside-Modifying Enzymes and β-Lactamases for Control of Resistant Bacteria

2020 ◽  
Vol 21 (10) ◽  
pp. 1011-1026
Author(s):  
Bruna O. Costa ◽  
Marlon H. Cardoso ◽  
Octávio L. Franco
Keyword(s):  
Drug Target ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Treatment Strategies ◽  
Resistance Mechanisms ◽  
Resistant Bacteria ◽  
Specific Chemical ◽  
Target Interaction ◽  
Multiresistant Bacteria ◽  
Acute Bacterial Infections

: Aminoglycosides and β-lactams are the most commonly used antimicrobial agents in clinical practice. This occurs because they are capable of acting in the treatment of acute bacterial infections. However, the effectiveness of antibiotics has been constantly threatened due to bacterial pathogens producing resistance enzymes. Among them, the aminoglycoside-modifying enzymes (AMEs) and β-lactamase enzymes are the most frequently reported resistance mechanisms. AMEs can inactivate aminoglycosides by adding specific chemical molecules in the compound, whereas β-lactamases hydrolyze the β-lactams ring, preventing drug-target interaction. Thus, these enzymes provide a scenario of multidrug-resistance and a significant threat to public health at a global level. In response to this challenge, in recent decades, several studies have focused on the development of inhibitors that can restore aminoglycosides and β-lactams activity. In this context, peptides appear as a promising approach in the field of inhibitors for future antibacterial therapies, as multiresistant bacteria may be susceptible to these molecules. Therefore, this review focused on the most recent findings related to peptide-based inhibitors that act on AMEs and β-lactamases, and how these molecules could be used for future treatment strategies.

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