Recent Advancements in Enzyme-Based Lateral Flow Immunoassays

Paper-based lateral-flow immunoassays (LFIAs) have achieved considerable commercial success and their impact in diagnostics is continuously growing. LFIA results are often obtained by visualizing by the naked eye color changes in given areas, providing a qualitative information about the presence/absence of the target analyte in the sample. However, this platform has the potential to provide ultrasensitive quantitative analysis for several applications. Indeed, LFIA is based on well-established immunological techniques, which have known in the last year great advances due to the combination of highly sensitive tracers, innovative signal amplification strategies and last-generation instrumental detectors. All these available progresses can be applied also to the LFIA platform by adapting them to a portable and miniaturized format. This possibility opens countless strategies for definitively turning the LFIA technique into an ultrasensitive quantitative method. Among the different proposals for achieving this goal, the use of enzyme-based immunoassay is very well known and widespread for routine analysis and it can represent a valid approach for improving LFIA performances. Several examples have been recently reported in literature exploiting enzymes properties and features for obtaining significative advances in this field. In this review, we aim to provide a critical overview of the recent progresses in highly sensitive LFIA detection technologies, involving the exploitation of enzyme-based amplification strategies. The features and applications of the technologies, along with future developments and challenges, are also discussed.

Download Full-text

A Lawsone–DAMN based colorimetric chemosensor for rapid naked-eye detection of mercury(ii)

New Journal of Chemistry ◽

10.1039/c6nj00430j ◽

2016 ◽

Vol 40 (8) ◽

pp. 6803-6811 ◽

Cited By ~ 12

Author(s):

Sharad R. Patil ◽

Amol S. Choudhary ◽

Nagaiyan Sekar

Keyword(s):

Selective Recognition ◽

Eye Detection ◽

Color Changes ◽

Naked Eye ◽

Colorimetric Chemosensor ◽

Highly Sensitive ◽

Naked Eye Detection ◽

Stoichiometric Complex

A highly sensitive and selective chemosensorLexhibited well-defined naked-eye visible color changes from yellow to pink, which was used for Hg2+detection in acetonitrile. For the selective recognition of Hg2+ions, it forms a 1 : 1 stoichiometric complex involving naphthoquinone hydroxyl and diaminomaleonitrile nitrogen functionalities.

Download Full-text

Effect of Citric Acid on Color Changes of Calcium Silicate-Based Cements an In Vitro Study

Applied Sciences ◽

10.3390/app11052339 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2339

Author(s):

Joanna Metlerska ◽

Till Dammaschke ◽

Mariusz Lipski ◽

Irini Fagogeni ◽

Anna Machoy-Mokrzyńska ◽

...

Keyword(s):

Citric Acid ◽

Calcium Silicate ◽

In Vitro Study ◽

Vitro Study ◽

Color Measurement ◽

Color Changes ◽

Naked Eye ◽

Root Canal Irrigants ◽

The Difference

The aim of the present in vitro study was to investigate the effects of 10% and 40% citric acid (CA) on the color of calcium silicate–based cements (CSCs) in comparison to the effects of common root canal irrigants. Samples of six CSCs (n = 6)—ProRoot MTA (Dentsply, Tulsa, OK, USA), Biodentine (Septodont, Saint-Maur-des-Fossés, France), MTA Plus (Avalon Biomed Inc, by Prevest Denpro Limited, Jammu, India), MTA Repair HP (Angelus, Londrina, PR, Brazil), Ortho MTA (BioMTA, Seoul, Korea), and Retro MTA (BioMTA, Seoul, Korea)—were immersed in 10% and 40% CA as well as 15% EDTA, 2% NaOCl, 2% CHX, and 0.9% NaCl for 15 min, 1 h, and 24 h. ΔE values, representing the difference between the final and baseline values of the color components, were then determined using a VITA Easyshade Compact 5.0 spectrophotometer. Naked-eye evaluation of the changes in color and structures of the materials was performed using our own scale. Upon immersion of the materials in both 10% and 40% CA, there were statistically significant differences between spectrophotometric color measurement results for all CSCs (P < 0.05). However, CA does not cause dark discoloration, observable with the naked eye, of any of the materials, such as NaOCl and CHX. Significant statistical differences were also found between all CSCs in terms of submersion duration (P < 0.05). CA, which could be an alternative to EDTA use, caused greater CSCs discoloration and changed some of their structures. Unless required by the therapeutic procedure, clinicians should pay attention to the fact that the irrigant may affect the CSCs discoloration and minimize the contact time of irrigant with CSCs.

Download Full-text

6-Axis Stress Tensor Sensor Using Multifaceted Silicon Piezoresistors

Micromachines ◽

10.3390/mi12030279 ◽

2021 ◽

Vol 12 (3) ◽

pp. 279

Author(s):

Kentaro Noda ◽

Jian Sun ◽

Isao Shimoyama

Keyword(s):

Stress Tensor ◽

Elastic Body ◽

Building Materials ◽

Sensor Response ◽

Stress Change ◽

Sensor Chip ◽

Naked Eye ◽

Highly Sensitive ◽

Wide Range

A tensor sensor can be used to measure deformations in an object that are not visible to the naked eye by detecting the stress change inside the object. Such sensors have a wide range of application. For example, a tensor sensor can be used to predict fatigue in building materials by detecting the stress change inside the materials, thereby preventing accidents. In this case, a sensor of small size that can measure all nine components of the tensor is required. In this study, a tensor sensor consisting of highly sensitive piezoresistive beams and a cantilever to measure all of the tensor components was developed using MEMS processes. The designed sensor had dimensions of 2.0 mm by 2.0 mm by 0.3 mm (length by width by thickness). The sensor chip was embedded in a 15 mm3 cubic polydimethylsiloxane (PDMS) (polydimethylsiloxane) elastic body and then calibrated to verify the sensor response to the stress tensor. We demonstrated that 6-axis normal and shear Cauchy stresses with 5 kPa in magnitudes can be measured by using the fabricated sensor.

Download Full-text

Multi-Quantum Dots-Embedded Silica-Encapsulated Nanoparticle-Based Lateral Flow Assay for Highly Sensitive Exosome Detection

Nanomaterials ◽

10.3390/nano11030768 ◽

2021 ◽

Vol 11 (3) ◽

pp. 768

Author(s):

Hyung-Mo Kim ◽

Chiwoo Oh ◽

Jaehyun An ◽

Seungki Baek ◽

Sungje Bock ◽

...

Keyword(s):

Quantum Dots ◽

Limit Of Detection ◽

Specific Binding ◽

Calf Serum ◽

Lateral Flow ◽

Lateral Flow Immunoassay ◽

Uniform Size ◽

Highly Sensitive ◽

Wide Range ◽

New Biomarkers

Exosomes are attracting attention as new biomarkers for monitoring the diagnosis and prognosis of certain diseases. Colorimetric-based lateral-flow assays have been previously used to detect exosomes, but these have the disadvantage of a high limit of detection. Here, we introduce a new technique to improve exosome detection. In our approach, highly bright multi-quantum dots embedded in silica-encapsulated nanoparticles (M–QD–SNs), which have uniform size and are brighter than single quantum dots, were applied to the lateral flow immunoassay method to sensitively detect exosomes. Anti-CD63 antibodies were introduced on the surface of the M–QD–SNs, and a lateral flow immunoassay with the M–QD–SNs was conducted to detect human foreskin fibroblast (HFF) exosomes. Exosome samples included a wide range of concentrations from 100 to 1000 exosomes/µL, and the detection limit of our newly designed system was 117.94 exosome/μL, which was 11 times lower than the previously reported limits. Additionally, exosomes were selectively detected relative to the negative controls, liposomes, and newborn calf serum, confirming that this method prevented non-specific binding. Thus, our study demonstrates that highly sensitive and quantitative exosome detection can be conducted quickly and accurately by using lateral immunochromatographic analysis with M–QD–SNs.

Download Full-text

A new phenothiazine-based fluorescent probe for detection of hydrazine with naked-eye color change properties

Chemical Papers ◽

10.1007/s11696-021-01859-6 ◽

2021 ◽

Author(s):

Nian Rao ◽

Yi Le ◽

Dan Li ◽

Yan Zhang ◽

Qin Wang ◽

...

Keyword(s):

Fluorescent Probe ◽

Color Change ◽

Eye Color ◽

Naked Eye

Download Full-text

Highly sensitive multiplex lateral flow immunoassay of phytopathogens using Au@Pt nanoparticles as the colorimetric and catalytic label

10.1063/5.0069147 ◽

2021 ◽

Author(s):

Vasily G. Panferov ◽

Shyatesa C. Razo ◽

Irina V. Safenkova ◽

Anatoly V. Zherdev ◽

Boris B. Dzantiev

Keyword(s):

Pt Nanoparticles ◽

Lateral Flow ◽

Lateral Flow Immunoassay ◽

Highly Sensitive

Download Full-text

Luminescent lanthanide nanoparticle-based imaging enables ultra-sensitive, quantitative and multiplexed in vitro lateral flow immunoassays

Nanoscale ◽

10.1039/d1nr03358a ◽

2021 ◽

Author(s):

F. Mousseau ◽

C. Féraudet Tarisse ◽

S. Simon ◽

T. Gacoin ◽

A. Alexandrou ◽

...

Keyword(s):

Optical Properties ◽

Lateral Flow ◽

Biomolecule Detection ◽

Nanoparticle Probes ◽

Highly Sensitive

We developed a portable, fast, highly sensitive and quantitative in vitro assay for on-site biomolecule detection by combining the remarkable optical properties of new lanthanide-doped nanoparticle probes with a simple reader coupled to a smartphone.

Download Full-text