Unlocking the potential of chitosan nanoparticle as a carrier for systemic acquired resistance (SAR)-inducing recombinant protein: A preliminary study

Abstract

Dieback disease stemmed from a phytopathogenic bacteria named Erwinia mallotivora is disastrous to papaya plant. Disease management action plan occurred stagnantly across the continent, until the discovery of proteinaceous hairpin which may catalyse systemic-acquired resistance (SAR) as plants’ defence mechanism. However, hairpin utilization is seriously flawed by its instability and limited bioavailability in plant. In lieu of this matter, nanobiotechnology approach through the encapsulation of hairpin within chitosan nanoparticles may be a mediator towards enhancement of sustained delivery as well as synergistic effect during foliar application. In this preliminary work, hrpN, a hairpin functional as SAR elicitor from Erwinia mallotivora, was well-expressed and purified in Escherichia coli system at molecular weight and concentration; 30 kDa and 1 µg/µL, respectively. Optimization of ionic gelation simultaneously revealed that optimal chitosan (CS) to sodium tripolyphosphate (TPP) volume ratio was found to be 2.4:1 ratio, yielding nano-sized particles with mean hydrodynamic diameter 66.27 ± 1.77 nm, and homogenously distributed with polydispersity index 0.189 ± 0.027. Subsequently, encapsulation of purified hrpN within CNP was formulated at various hrpN concentration. Following that, encapsulation of 0.04 mg/mL hrpN within optimized CNP produced hrpN-encapsulated chitosan nanoparticles (CNP-hrpN) with small size (106.34 ± 2.053 nm), stable and well-dispersed (0.188 ± 0.011), as well as possessing excellent encapsulation efficiency (81.84 ± 3.43%). The outcome from current work portrayed the potential of chitosan nanoparticle to carry biomolecules with desired properties.