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Molecules
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Novel Fluorescent Metal Nanoclusters as Biosensors
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Novel Fluorescent Metal Nanoclusters as Biosensors

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Analytical Chemistry".

Deadline for manuscript submissions: closed (30 June 2020) | Viewed by 10348

Special Issue Editor

Dr. Bidisha Sengupta

E-Mail Website
Guest Editor
Department of Chemistry & Biochemistry, Stephen F. Austin State University, Nacogdoches, TX 75964, USA
Interests: silver nanoclusters; unusual DNA structures; protein and peptide misfolding; excited state proton transfer; plant products; antioxidants; anti biofilm agents

Special Issue Information

Dear Colleagues,

Metal nanoclusters (NCs) with core sizes of less than 2 nm, are one of the most studied systems in nanomaterials. The unique optical, magnetic, and catalytic properties of NCs are attributed to their quantized molecular-like properties, such as HOMO–LUMO transition with discrete energy levels, and luminescence. Research in fluorescent silver, gold and copper NCs have come into prominence due to their low toxicity, ultra-fine size, and biocompatibility, which make them an ideal candidate for functional nanomaterials with applications in the biomedical field. Templates, including single-stranded oligonucleotides and peptides/proteins, are required to synthesize the NCs and atomic levels of precision in the size of the cluster can be reached by tailoring the structure and composition of the capping agents. The optical properties of these NCs can also be manipulated by controlling the microenvironment of the NC or through bioconjugation, leading to the development of a more versatile sensing platform. Fluorescent metal NCs have been widely used as sensors/probes due to their significant response to certain changes in their surrounding medium, such as pH, temperature, oxidative stress, or the presence of different solutes such as metal ions. In view of the increasing research interest in this topic, in this Special Issue of Molecules, we invite articles related to the synthesis, characterization, and applications of metal NCs. We look forward to original research articles and reviews with potential relevance to NC-based biomedical applications (imaging, antimicrobial agents and therapy). Articles which emphasize the varied synthesis mechanisms of NCs, and characterize their applications as biosensors are also welcome.

Dr. Bidisha Sengupta
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • silver, gold, copper nanoclusters
  • protein scaffolds
  • DNA templates
  • fluorescent probes
  • nanosensors
  • nanomaterials
  • bioimaging
  • excited state electron transfer/transport
  • fluorescence anisotropy
  • luminescence

Published Papers (3 papers)

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Research

13 pages, 2823 KiB  
Article
Spectroscopic Study on Pseudomonas Aeruginosa Biofilm in the Presence of the Aptamer-DNA Scaffolded Silver Nanoclusters
by Bidisha Sengupta, Prakash Adhikari, Esther Mallet, Ronald Havner and Prabhakar Pradhan
Molecules 2020, 25(16), 3631; https://doi.org/10.3390/molecules25163631 - 10 Aug 2020
Cited by 11 | Viewed by 2377
Abstract
We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of [...] Read more.
We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of secondary structures, UV/Vis absorption, and fluorescence spectroscopic studies confirmed the formation of the fluorescent Ag-NC on the DNA templates. Furthermore, mesoscopic physics-based partial wave spectroscopy (PWS) was used to analyze the backscattered light signal that can detect the degree of nanoscale mass density/refractive index fluctuations to identify the biofilm formation, comparatively among the different aptamers with respect to the control sample. The importance of the secondary structure of the aptamer DNA in targeting, successfully binding with the cells and delivering the Ag-NC, is evidenced by the decrease in disorder strength (Ld) of the Ag-NC treated samples compared to the untreated PA cells, which showed the abundance of higher Ld in the PWS studies. The higher Ld value attributed to the higher mass density fluctuations and the formation of biofilm. We envision this study to open a new avenue in using a powerful optical microscopic technique like PWS in detection, and DNA aptamer enclosed silver nanoclusters to prevent biofilms for opportunist pathogens like Pseudomonas aeruginosa. Full article
(This article belongs to the Special Issue Novel Fluorescent Metal Nanoclusters as Biosensors)
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15 pages, 1326 KiB  
Article
Micro RNA Sensing with Green Emitting Silver Nanoclusters
by Liam E. Yourston and Alexey V. Krasnoslobodtsev
Molecules 2020, 25(13), 3026; https://doi.org/10.3390/molecules25133026 - 2 Jul 2020
Cited by 13 | Viewed by 2548
Abstract
Micro RNA (miR) are regulatory non-coding RNA molecules, which contain a small number of nucleotides ~18–28 nt. There are many various miR sequences found in plants and animals that perform important functions in developmental, metabolic, and disease processes. miRs can bind to complementary [...] Read more.
Micro RNA (miR) are regulatory non-coding RNA molecules, which contain a small number of nucleotides ~18–28 nt. There are many various miR sequences found in plants and animals that perform important functions in developmental, metabolic, and disease processes. miRs can bind to complementary sequences within mRNA molecules thus silencing mRNA. Other functions include cardiovascular and neural development, stem cell differentiation, apoptosis, and tumors. In tumors, some miRs can function as oncogenes, others as tumor suppressors. Levels of certain miR molecules reflect cellular events, both normal and pathological. Therefore, miR molecules can be used as biomarkers for disease diagnosis and prognosis. One of these promising molecules is miR-21, which can serve as a biomarker with high potential for early diagnosis of various types of cancer. Here, we present a novel design of miR detection and demonstrate its efficacy on miR-21. The design employs emissive properties of DNA-silver nanoclusters (DNA/AgNC). The detection probe is designed as a hairpin DNA structure with one side of the stem complimentary to miR molecule. The binding of target miR-21 opens the hairpin structure, dramatically modulating emissive properties of AgNC hosted by the C12 loop of the hairpin. “Red” fluorescence of the DNA/AgNC probe is diminished in the presence of the target miR. At the same time, “green” fluorescence is activated and its intensity increases several-fold. The increase in intensity of “green” fluorescence is strong enough to detect the presence of miR-21. The intensity change follows the concentration dependence of the target miR present in a sample, which provides the basis of developing a new, simple probe for miR detection. The detection strategy is specific, as demonstrated using the response of the DNA/AgNC probe towards the scrambled miR-21 sequence and miR-25 molecule. Additionally, the design reported here is very sensitive with an estimated detection limit at ~1 picomole of miR-21. Full article
(This article belongs to the Special Issue Novel Fluorescent Metal Nanoclusters as Biosensors)
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14 pages, 3335 KiB  
Article
A Chemiluminescent Method for the Detection of H2O2 and Glucose Based on Intrinsic Peroxidase-Like Activity of WS2 Quantum Dots
by Mahsa Haddad Irani-nezhad, Alireza Khataee, Javad Hassanzadeh and Yasin Orooji
Molecules 2019, 24(4), 689; https://doi.org/10.3390/molecules24040689 - 14 Feb 2019
Cited by 87 | Viewed by 5196
Abstract
Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS2 quantum dots (WS2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS2 QDs with a size [...] Read more.
Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS2 quantum dots (WS2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS2 QDs with a size of 1–1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS2 QDs with uniform morphology showed a high catalytic effect in destroying H2O2. The peroxidase-like activity of synthesized nanostructures was studied in H2O2 chemical and electrochemical reduction systems. The mimetic effect of WS2 QDs was also shown in an H2O2–rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H2O2 is one of the products which can be determined. Under optimum conditions, H2O2 can be detected in the concentration range of 0–1000 nmol·L−1, with a detection limit of 2.4 nmol·L−1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01–30 nmol·L−1, with a limit of detection (3S) of 4.2 nmol·L−1. Full article
(This article belongs to the Special Issue Novel Fluorescent Metal Nanoclusters as Biosensors)
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