Deformable molecularly imprinted nanogels permit sensitivity-gain in plasmonic sensing

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The rapid spread of the Coronavirus Disease 2019 (COVID-19) pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pathogen has generated a huge international public health emergency. Currently the reference diagnostic technique for virus determination is Reverse Transcription Polymerase Chain Reaction (RT-PCR) real time analysis that requires specialized equipment, reagents and facilities and typically 3–4 h to perform. Thus, the realization of simple, low-cost, small-size, rapid and point-of-care diagnostics tests has become a global priority. In response to the current need for quick, highly sensitive and on-site detection of the SARS-CoV-2 virus in several aqueous solutions, a specific molecularly imprinted polymer (MIP) receptor has been designed, realized, and combined with an optical sensor. More specifically, the proof of concept of a SARS-CoV-2 sensor has been demonstrated by exploiting a plasmonic plastic optical fiber sensor coupled with a novel kind of synthetic MIP nano-layer, especially designed for the specific recognition of Subunit 1 of the SARS-CoV-2 Spike protein. First, we have tested the effectiveness of the developed MIP receptor to bind the Subunit 1 of the SARS-CoV-2 spike protein, then the results of preliminary tests on SARS-CoV-2 virions, performed on samples of nasopharyngeal (NP) swabs in universal transport medium (UTM) and physiological solution (0.9% NaCl), were compared with those obtained with RT-PCR. According to these preliminary results, the sensitivity of the proposed optical-chemical sensor proved to be higher than the RT-PCR one. Furthermore, a relatively fast response time (about 10 min) to the virus was obtained without the use of additional reagents.

Section: Introductionmentioning

confidence: 99%

Proof of Concept for a Quick and Highly Sensitive On-Site Detection of SARS-CoV-2 by Plasmonic Optical Fibers and Molecularly Imprinted Polymers

Cennamo

D’Agostino

Perri

et al. 2021

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“…Optimized conditions are reported in the Results and Discussion section in paragraph 3. The gold surfaces were coated with a self-assembled monolayer of α-lipoic acid according to [20]. Then, the effect of different molar ratios of EDC and sulfo-NHS (10:10, 20:10, 40:10, and 80:10 mM) on the immobilization of the antibody were tested as a function of the incubation time (20 ÷ 120 min), using a fluorescent antibody (IgGFITC; 5 g) as a probe and measuring the fluorescent signals by means of fluorescence microscopy.…”

Section: Gold Surface Functionalizationmentioning

confidence: 99%

“…The POF offers several advantages over glass fibers: it is easy to manipulate and, given its flexibility, it has a great numerical aperture and possesses a large diameter. The POF can be derivatized with a variety of recognition elements, such as proteins and antibodies [17], aptamers [18] and biomimetics, such as molecularly imprinted polymers [19], including molecularly imprinted nanogels [20], offering a versatile platform for biosensing. Moreover, the POF biosensor has demonstrated high sensitivity, down to the pM and fM levels, thus it matches the need for the detection of biomarkers in body fluids with low concentrations.…”

Section: Introductionmentioning

confidence: 99%

A Surface Plasmon Resonance Plastic Optical Fiber Biosensor for the Detection of Pancreatic Amylase in Surgically-Placed Drain Effluent

Pasquardini¹,

Cennamo

Malleo

et al. 2021

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Postoperative pancreatic fistula (POPF), the major driver of morbidity and mortality following pancreatectomy, is caused by an abnormal communication between the pancreatic ductal epithelium and another epithelial surface containing pancreas-derived, enzyme-rich fluid. There is a strong correlation between the amylase content in surgically-placed drains early in the postoperative course and the development of POPF. A simple and cheap method to determine the amylase content from the drain effluent has been eagerly advocated. Here, we developed an amylase optical biosensor, based on a surface plasmon resonance (SPR) plastic optical fiber (POF), metallized with a 60 nm layer of gold and interrogated with white light. The sensor was made specific by coupling it with an anti-amylase antibody. Each surface derivatization step was optimized and studied by XPS, contact angle, and fluorescence. The POF-biosensor was tested for its response to amylase in diluted drain effluents. The volume of sample required was 50 µL and the measurement time was 8 min. The POF-biosensor showed selectivity for amylase, a calibration curve log-linear in the range of 0.8–25.8 U/L and a limit of detection (LOD) of ~0.5 U/L. In preliminary tests, the POF-biosensor allowed for the measurement of the amylase content of diluted surgically-placed drain effluents with an accuracy of >92% with respect to the gold standard. The POF-biosensor allows for reliable measurement and could be implemented to allow for a rapid bedside assessment of amylase value in drains following pancreatectomy.

“…The MIP composition can be optimized by means of molecular modeling tools [ 29 ], while in terms of materials, the most exploited for the preparation of MIP layers and nanoparticles are polyacrylates, polymethacrylates, polyacrylamides and electroactive materials such as anilines and p-phenylboronates [ 40 ]. Of particular interest is the class of nanogels, such as poly-N-isopropylacrylamide and copolymers [ 34 , 35 ], for their responsive properties of shrinking and swelling dependent on the environment [ 41 ] that offer advantages in terms of adaptive recognition sites, thus making MIP NPs suitable for the recognition of macromolecules [ 42 ] and for signal amplification [ 41 ].…”

Section: Molecularly Imprinted Polymers (Mips)mentioning

confidence: 99%

“…The MIP NPs were observed to deform at binding to HTR, with the mean Young’s modulus measured by AFM passing from 17 ± 6 kPa for free NPs to 56 ± 18 kPa for bound NPs. Such analyte-induced MIP-NP-deformations amplified the resonance shift, enabling the achievement of ultra-low sensitivities: a LoD of 1.2 fM and a linear dynamic range of concentrations from 1.2 fM to 1.8 pM [ 41 ]. To date, it appears that gaining the spatial control of MIP deformation events, and playing with MIP films and MIP NPs that deform close to the plasmon, is the key to dramatically improve the sensor sensitivity, enabling nanosensors characterized by quasi single molecule detection to be attained.…”

Section: Mip Coupled To Photonic Structuresmentioning

confidence: 99%

Molecular Imprinted Polymers Coupled to Photonic Structures in Biosensors: The State of Art

Chiappini

Pasquardini²,

Bossi

2020

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Optical sensing, taking advantage of the variety of available optical structures, is a rapidly expanding area. Over recent years, whispering gallery mode resonators, photonic crystals, optical waveguides, optical fibers and surface plasmon resonance have been exploited to devise different optical sensing configurations. In the present review, we report on the state of the art of optical sensing devices based on the aforementioned optical structures and on synthetic receptors prepared by means of the molecular imprinting technology. Molecularly imprinted polymers (MIPs) are polymeric receptors, cheap and robust, with high affinity and selectivity, prepared by a template assisted synthesis. The state of the art of the MIP functionalized optical structures is critically discussed, highlighting the key progresses that enabled the achievement of improved sensing performances, the merits and the limits both in MIP synthetic strategies and in MIP coupling.