Abstract
Nanoparticles have been conjugated to biological systems for numerous applications such as self-assembly, sensing, imaging, and therapy. Development of more reliable and robust biosensors that exhibit high response rate, increased detection limit, and enhanced useful lifetime is in high demand. We have developed a sensing platform by the conjugation of β-galactosidase, a crucial enzyme, with lab-synthesized gel-like carbon dots (CDs) which have high luminescence, photostability, and easy surface functionalization. We found that the conjugated enzyme exhibited higher stability towards temperature and pH changes in comparison to the native enzyme. This enriched property of the enzyme was distinctly used to develop a stable, reliable, robust biosensor. The detection limit of the biosensor was found to be 2.9 × 10−4 M, whereas its sensitivity was 0.81 µA·mmol−1·cm−2. Further, we used the Langmuir monolayer technique to understand the surface properties of the conjugated enzyme. It was found that the conjugate was highly stable at the air/subphase interface which additionally reinforces the suitability of the use of the conjugated enzyme for the biosensing applications.
Highlights
Different nanoparticles and quantum dots have been employed in many applications like catalysis [1,2], imaging [3,4], drug delivery [5,6,7,8], and biosensing [9,10,11]
This study showed that the conjugate was stable enough to remain as a Langmuir monolayer at the air/subphase interface
In doing so a linear relationship was established (Figure 10). This observation reinforces the interpretation that the conjugate of carbon dots (CDs) and β-galactosidase remains at the air/subphase interface facilitating the development of a biosensor
Summary
Different nanoparticles and quantum dots have been employed in many applications like catalysis [1,2], imaging [3,4], drug delivery [5,6,7,8], and biosensing [9,10,11]. Different immobilization techniques have been employed to maintain enzyme stability and reusability [17,18] In this case, the use of inorganic and organic supports can sufficiently change the chemical and physical properties of the enzyme which in turn can decrease its activity. Have shown that ironperoxide oxide peroxidase with carbon dots/CoFe layered hydroxides been used in hydrogen nanoparticles glutamineand proline-based osmolytes inhibit protein aggregation sensing [23].conjugated. New property of the enzyme conjugate led to the idea to prepare a biosensor
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