Cellulosic nitrogen doped carbon quantum dots hydrogels with fluorescence/visco-elastic properties for pH- and temperature-sensitivity

Abstract

The swelled hydroxyl ethyl cellulose-N–CQDs-g-poly(co-acrylamido-2-methyl-1-propane sulfonic Acid) prepared from hydroxyl ethyl cellulose (HEC), nitrogen doped carbon quantum dots (N–CQDs) and poly(co-acrylamido-2-methyl-1-propane sulfonic Acid) (poly(co-AMPS)), as base polymer, could be used as a pH/thermo-responsive hydrogels. The H3 hydrogels with 15 % N–CQDs in water undergo a reversible hydrophilic–hydrophobic phase transition around a LCST of 55 °C. Further, The HB, H1 and H2 exhibited the maximum swelling ratio at pH = 12, while, H3 exhibited the maximum swelling at PH = 6. This may be due to acidic groups of SA and/or the positively charge of N–CQDs. It was proved that HEC-N–CQDs-g-poly(co-AMPS) hydrogels are elastic in nature while the HEC-g-poly(co-AMPS) hydrogels hydrogel is viscous in nature. Both viscoelastic moduli (G′ and G″) moduli modified over huge variety of angular frequency region. Further, the properties of HEC-N–CQDs-g-poly(co-AMPS) hydrogels grew to become in to elastic shape in comparison to HEC-g-poly(co-AMPS) hydrogels without N–CQDs (i.e. HB). The H1, H2 and H3 (i.e. different forms of HEC-g-poly(co-AMPS) hydrogels with different concentration of N–CQDs) may be applied in biomedical packages including building smooth and elastic tissues consisting of skin, skeletal muscle, and blood vessels, as well as, actuators for drug delivery use. But HB may be acclaimed as a scaffold for burned wound dressing. The fluorescence properties of the prepared hydrogels due to the fact of the addition of N–CQDs making it appropriate for use as a sensor.