scholarly journals Conjugation of Carboxylated Graphene Quantum Dots with Cecropin P1 for Bacterial Biosensing Applications

2020 ◽  
Author(s):  
Jonathan Bruce ◽  
Jude Clapper
Keyword(s):  
Quantum Dots ◽  
Drinking Water ◽  
Structural Modification ◽  
Light Emission ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Strong Light ◽  
E Coli ◽  
Cecropin P1 ◽  
Reliable Detection

<p>Quantum dots have proven to be strong candidates for biosensing applications in recent years, due to their strong light emission properties and their ability to be modified with a variety of functional groups for the detection of different analytes. Here, we investigate the use of conjugated carboxylated graphene quantum dots (CGQDs) for the detection of <i>E. coli</i>, using a biosensing procedure that focuses on measuring changes in fluorescence quenching. Our CGQDs were conjugated with cecropin P1, a naturally-produced antibacterial peptide that facilitates the attachment of CGQDs to <i>E. coli</i> cells. We also confirm the structural modification of these conjugated CGQDs in addition to analyzing their optical characteristics. Our findings have the potential to be used in situations where rapid, reliable detection of bacteria in liquids, such as drinking water, is required, especially given our biosensor’s relatively low observed limit of detection (LOD).</p><br>

scholarly journals Conjugation of Carboxylated Graphene Quantum Dots with Cecropin P1 for Bacterial Biosensing Applications

2020 ◽  
Author(s):  
Jonathan Bruce ◽  
Jude Clapper
Keyword(s):  
Quantum Dots ◽  
Structural Modification ◽  
Light Emission ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Strong Light ◽  
E Coli ◽  
Cecropin P1 ◽  
Compact Field ◽  
Test Kit

<p>Quantum dots have proven to be strong candidates for biosensing applications in recent years, due to their strong light emission properties and their ability to be modified with a variety of functional groups for the detection of different analytes. Here, we investigate the use of conjugated carboxylated graphene quantum dots (CGQDs) for the detection of <i>E. coli</i>, using a biosensing procedure that focuses on measuring changes in fluorescence quenching. We have also further developed this biosensing assay into a compact, field-deployable test kit focused on rapidly measuring changes in absorbance to determine bacterial concentration. Our CGQDs were conjugated with cecropin P1, a naturally-produced antibacterial peptide that facilitates the attachment of CGQDs to <i>E. coli</i> cells. We also confirm the structural modification of these conjugated CGQDs in addition to analyzing their optical characteristics. Our findings have the potential to be used in situations where rapid, reliable detection of bacteria in liquids, such as drinking water, is required, especially given our biosensor’s relatively low observed limit of detection (LOD).</p><br>

scholarly journals Conjugation of Carboxylated Graphene Quantum Dots with Cecropin P1 for Bacterial Biosensing Applications

2020 ◽  
Author(s):  
Jonathan Bruce ◽  
Jude Clapper
Keyword(s):  
Quantum Dots ◽  
Structural Modification ◽  
Light Emission ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Strong Light ◽  
E Coli ◽  
Cecropin P1 ◽  
Compact Field ◽  
Test Kit

<p>Quantum dots have proven to be strong candidates for biosensing applications in recent years, due to their strong light emission properties and their ability to be modified with a variety of functional groups for the detection of different analytes. Here, we investigate the use of conjugated carboxylated graphene quantum dots (CGQDs) for the detection of <i>E. coli</i>, using a biosensing procedure that focuses on measuring changes in fluorescence quenching. We have also further developed this biosensing assay into a compact, field-deployable test kit focused on rapidly measuring changes in absorbance to determine bacterial concentration. Our CGQDs were conjugated with cecropin P1, a naturally-produced antibacterial peptide that facilitates the attachment of CGQDs to <i>E. coli</i> cells. We also confirm the structural modification of these conjugated CGQDs in addition to analyzing their optical characteristics. Our findings have the potential to be used in situations where rapid, reliable detection of bacteria in liquids, such as drinking water, is required, especially given our biosensor’s relatively low observed limit of detection (LOD).</p><br>

Size-Dependent Antibacterial Behavior of Graphene Quantum Dots

2013 ◽  
Author(s):  
Siheng Su ◽  
Carla B. Shelton ◽  
Jingjing Qiu
Keyword(s):  
Quantum Dots ◽  
Surface Chemistry ◽  
Graphene Quantum Dots ◽  
Gel Filtration ◽  
Filtration Method ◽  
E Coli ◽  
Size Dependent ◽  
Mtt Method ◽  
Diphenyltetrazolium Bromide ◽  
Standard Plate

In this study, the antibacterial behavior of differing sized graphene quantum dots (GQDs) was studied. The gram negative bacteria, Escherichia coli (E. coli), were used as the bacteria mode. Different sized GQDs with tunable fluorescent colors were acquired by a gel-filtration method. The size, surface chemistry, and photoluminescence properties of GQDs were characterized, respectively. The viability of GQDs treated bacteria was determined by the standard plate counting method. Moreover, the reactive oxidative species (ROS) level was detected by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) method. The integrality of the bacteria membrane was observed under the scanning electron microscopy (SEM). The experimental results indicated that GQDs demonstrated size-dependent and surface chemistry-dependent antibacterial behaviors. This research provided insightful guidelines in the selection of suitable GQDs for their potential bioapplications.

scholarly journals One-Step Preparation of Nitrogen-Doped Graphene Quantum Dots With Anodic Electrochemiluminescence for Sensitive Detection of Hydrogen Peroxide and Glucose

2021 ◽  
Vol 9 ◽  
Author(s):  
Zheng Yanyan ◽  
Jing Lin ◽  
Liuhong Xie ◽  
Hongliang Tang ◽  
Kailong Wang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Quantum Dots ◽  
Limit Of Detection ◽  
Hydrothermal Process ◽  
Graphene Quantum Dots ◽  
Sensitive Detection ◽  
Uniform Size ◽  
Nitrogen Doped ◽  
Nitrogen Doped Graphene ◽  
One Step

Simple and efficient synthesis of graphene quantum dots (GQDs) with anodic electrochemiluminescence (ECL) remains a great challenge. Herein, we present an anodic ECL-sensing platform based on nitrogen-doped GQDs (N-GQDs), which enables sensitive detection of hydrogen peroxide (H2O2) and glucose. N-GQDs are easily prepared using one-step molecular fusion between carbon precursor and a dopant in an alkaline hydrothermal process. The synthesis is simple, green, and has high production yield. The as-prepared N-GQDs exhibit a single graphene-layered structure, uniform size, and good crystalline. In the presence of H2O2, N-GQDs possess high anodic ECL activity owing to the functional hydrazide groups. With N-GQDs being ECL probes, sensitive detection of H2O2 in the range of 0.3–100.0 μM with a limit of detection or LOD of 63 nM is achieved. As the oxidation of glucose catalyzed by glucose oxidase (GOx) produces H2O2, sensitive detection of glucose is also realized in the range of 0.7–90.0 μM (LOD of 96 nM).

scholarly journals Fluorescent Nanosensor based on Molecularly Imprinted Polymers Coated on Graphene Quantum Dots for Fast Detection of Antibiotics

2018 ◽  
Author(s):  
Tongchang Zhou ◽  
Arnab Halder ◽  
Yi Sun
Keyword(s):  
Quantum Dots ◽  
Fluorescence Intensity ◽  
Molecularly Imprinted Polymers ◽  
Limit Of Detection ◽  
Sol Gel ◽  
Graphene Quantum Dots ◽  
Carboxyl Groups ◽  
One Pot ◽  
Molecularly Imprinted ◽  
Imprinted Polymers

In this work, we firstly explored a mild, clean, and highly efficient approach for the synthesis of graphene quantum dots (GQDs). GQDs with carboxyl groups or amino groups, were prepared from one-pot environmentally friendly method assisted by hydrogen peroxide, respectively. It was proved that carboxyl groups played an important role in the fluorescence quenching. Based on these findings, we developed a novel fluorescent nanosensor by combining molecularly imprinted polymers (MIPs) with carboxyl functionalized GQDs for the determination of tetracycline (TC) in aqueous samples. The nanocomposite was prepared using a sol-gel process. GQDs-MIPs showed strong fluorescent emission at 410 nm when excited at 360 nm, which was subsequently quenched in the presence of TC. Under optimum conditions, the fluorescence intensity of GQDs-MIPs decreased in response to the increase of TC concentration with good linearity rage of 1.0-104 &micro;g L-1. The limit of detection was determined to be 1 &micro;g L-1. The fluorescence intensity of GQDs-MIPs was more strongly quenched by TC compared to the corresponding non-imprinted polymers, GQDs-NIPs. With the high sensitivity, the material was also successfully worked for the detection of TC in real spiked milk samples.

scholarly journals Electrocatalytic determination of levodopa in presence of cabergoline using carbon paste electrode modified with graphene quantum dots/2-chlorobenzoyl ferrocene/ionic liquid

2021 ◽  
Author(s):  
Peyman Mohammadzadeh Jahani
Keyword(s):  
Quantum Dots ◽  
Ionic Liquid ◽  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Simultaneous Detection ◽  
Phosphate Buffer Solution ◽  
Carbon Paste ◽  
Paste Electrode

The electrochemical sensor was fabricated for the simultaneous determination of levodopa and cabergoline using carbon paste electrode (CPE) modified with graphene quantum dots (GQD), 2-chlorobenzoyl ferrocene (2CBF) and ionic liquid (IL). Then, the electrochemical behavior of levodopa alone and simultaneously with cabergoline at the surface of GQDs/2CBF/IL/CPE was investigated in phosphate buffer solution (PBS). Under optimal PBS, pH=7 condition, oxidation peak current has been found proportional to levodopa concentration in the range between 0.07 μM and 500.0 μM, with the limit of detection (LOD) of 0.02 μM (S/N=3). Outputs showed that at GQDs/2CBF/IL/CPE surface, the levodopa and cabergoline oxidation peaks are separated by the potential difference of 200 mV. In addition, it was found that this modified electrode possesses acceptable sensitivity, selectivity, stability and repeatability. All these properties were sufficient to allow simultaneous detection of levodopa and cabergoline in real samples at the surface of GQDs/2CBF/IL/CPE. This was supported by the successful application of this electro­chemical sensor electrode for the determination of levodopa and cabergoline in urine, serum, and cabergoline tablets.

scholarly journals White-light emission of blue-luminescent graphene quantum dots by europium (III) complex incorporation

Carbon ◽  
2017 ◽  
Vol 124 ◽  
pp. 479-485 ◽  
Author(s):  
Sejung Kim ◽  
Joon Kyo Seo ◽  
Jun Hong Park ◽  
Youngjun Song ◽  
Ying Shirley Meng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
Light Emission ◽  
Graphene Quantum Dots ◽  
White Light Emission
Sign in / Sign up

Export Citation Format

Share Document