Point-of-Care Assay of Alkaline Phosphatase Enzymatic Activity Using a Thermometer or Temperature Discoloration Sticker as Readout

Abstract

Alkaline phosphatase (ALP) is a significant biomarker in clinical diagnostics, and the abnormal level of ALP enzyme in serum is closely related to various diseases such as bone or liver cancer, bone metastases, and extrahepatic biliary obstruction. Herein a simple and portable photothermal biosensor was developed for sensitive detection of ALP enzyme based on the formation of polydopamine (PDA) nanoparticles using a thermometer or temperature discoloration sticker as readout. A MnO2 nanosheet was first prepared using a novel one-pot strategy which was operationally simple and not overly time-consuming. Then dopamine (DA) was quickly polymerized into PDA nanoparticles in the presence of the MnO2 nanosheet. When the model analyte ALP was present, the substrate 2-phospho-l-ascorbic acid trisodium salt (AAP) was catalytically hydrolyzed into l-ascorbic acid (AA), resulting in the inhibition of the formation of the PDA nanoparticles owing to the fact that the MnO2 nanosheet was reduced to Mn2+ by the generated AA. Thus, a portable biosensor based on the photothermal properties of PDA nanoparticles for ALP enzyme detection was established with a detection limit as low as 0.1 U/L (thermometer) and 1 U/L (temperature discoloration sticker). In addition, it also showed excellent sensing performance for the ALP assay in human serum. Such a simple, label-free, cost-effective, and sensitive assay could exhibit real potential application for ALP detection and early diagnosis, especially in developing countries or remote regions.

CDs–MnO2–TPPS Ternary System for Ratiometric Fluorescence Detection of Ascorbic Acid and Alkaline Phosphatase

“…The serum samples were treated with trichloroacetic acid and N -ethylmaleimide to deactivate proteins in the serum to avoid protein interference. 17 After centrifugation at 12,000 rpm for 20 min, the supernatant was adjusted to pH 7.4 and diluted 100-fold. Then, ALP solutions at different activities were spiked into the treated serum samples and detected using the above-mentioned method.…”

Advances in Sensing Technologies for Monitoring of Bone Health

“…In addition to the popular electrochemical and acoustic biosensors, recently Liu et al developed a portable photothermal biosensor to detect ALP enzymes on the basis of polydopamine (PDA) nanoparticle formation by using a thermometer as a read-out or temperature discoloration sticker, as indicated in Figure 8 [144]. This biosensor can work on a very low detection limit of 0.1 unit/length (U/L) for a thermometer and 1.0 U/L for a temperature discoloration sticker.…”

“…The majority of bone biosensors are used to detect a single biomarker of bone Figure 8. Photothermal biosensor for the measurement of ALP (reproduced with permission from reference [144], copyright 2019 American Chemical Society).…”

“…Photothermal biosensor for the measurement of ALP (reproduced with permission from reference[144], copyright 2019 American Chemical Society).…”

Alkaline Phosphatase‐based Electrochemical Analysis for Point‐of‐Care Testing

“…Enzymes can be linked to recognition components, such as antibodies for the target molecules. Among many types of enzymes, alkaline phosphatase (ALP) is one of the most commonly used in several bioanalytical methods (e. g., photoluminescence [3], bioluminescence [4], colorimetric [5], photothermal [6], and electrophoresis [7,8]) because of its high turnover number and low cost [9]. ALP is present in many human tissues, including liver, bones, kidneys, and placenta and catalyzes the hydrolysis of orthophosphoric monoesters into alcohols [10].…”