posted on 2023-12-18, 18:33authored byNurul
Farhana Ahmad Aljafree, Mohamad Firdaus Ahmad, Umar Abd Aziz, Mostafa Yousefzadeh Borzehandani, Adila Mohamad Jaafar, Norhayu Asib, Ha L. Nguyen, Mohamed Ibrahim Mohamed Tahir, Muhammad Alif Mohammad Latif, Kyle E. Cordova, Mohd Basyaruddin Abdul Rahman
Agrichemical adjuvants that combine a highly selective,
efficient,
and active mode of operation are critically needed to realize a more
sustainable approach to their usage. Herein, we report the synthesis
and full characterization of two new metal–organic frameworks
(MOFs), termed UPMOF-1 and UPMOF-2, that were constructed from eco-friendly
Ca2+ ions and naturally occurring, low-molecular weight
plant acids, l-malic and d-tartaric acid, respectively.
Upon structural elucidation of both MOFs, a widely used fungicide,
hexaconazole (Hex), was loaded on the structures, reaching binding
affinities of −5.0 and −3.5 kcal mol–1 and loading capacities of 63% and 62% for Hex@UPMOF-1 and Hex@UPMOF-2,
respectively, as a result of the formation of stable host–guest
interactions. Given the framework chemistry of the MOFs and their
predisposition to disassembly under relevant agricultural conditions,
the sustained release kinetics were determined to show nearly quantitative
release (98% and 95% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively)
after >500 h, a release profile drastically different than the
control
(>80% release in 24 h), from which the high efficiency of these
new
systems was established. To confirm their high selectivity and activity, in vitro and in vivo studies were performed
to illustrate the abilities of Hex@UPMOF-1 and Hex@UPMOF-2 to combat
the known aggressive pathogen Ganoderma boninense that causes basal stem rot disease in oil palm. Accordingly, at
an extremely low concentration of 0.05 μg mL–1, both Hex@UPMOF-1 and Hex@UPMOF-2 were demonstrated to completely
inhibit (100%) G. boninense growth, and during a
26 week in vivo nursery trial, the progression of
basal stem rot infection was completely halted upon treatment with
Hex@UPMOF-1 and Hex@UPMOF-2 and seedling growth was accelerated given
the additional nutrients supplied via the disassembly of the MOFs.
This study represents a significant step forward in the design of
adjuvants to support the environmentally responsible use of agrichemical
crop protection.