Agrochemical delivery system based on enzyme- or ph- responsive amphiphilic peg-dendron hybrids
A technology for agrochemicals and delivery systems, which is applied in the field of amphiphilic hybrid delivery systems, and can solve problems affecting the release rate and the space environment
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Embodiment 1
[0194] Example 1 - Materials and Methods
[0195] Materials: poly(ethylene glycol) methyl ether (2kDa, 5kDa and 10kDa), 2-(Boc-amino)-ethanethiol (97%), 2,2-dimethoxy-2-phenylphenethyl Ketone (DMPA, 99%), penicillin G amidase (PGA) from Escherichia coli, esterase (PLE) from pig liver, allyl bromide (99%), 4-nitrophenol (99.5%), N , N'-dicyclohexylcarbodiimide (DCC, 99%), LH20 and dry DMF were purchased from Sigma-Aldrich. Cystamine hydrochloride (98%), potassium hydroxide and DIPEA were purchased from Merck. Trifluoroacetic acid (TFA) was purchased from Alfa Aesar and phenylacetic acid was purchased from Fluka. Silica gel 0.040-0.063 mm, sodium hydroxide and all solvents were purchased from Bio-Lab and used as received. All solvents are HPLC grade. Deuterated solvents for NMR were purchased from Cambridge Isotope Laboratories, Inc.
[0196] Instrumentation: HPLC: All measurements were recorded on a Waters Alliance e2695 separations module equipped with a Waters 2998 ...
Embodiment 2
[0241] Example 2: Synthesis of Amphiphilic PEG-Dendron Hybrids
[0242] 2,4-D was used as an initial model compound, which was conjugated to the hydroxyl endgroup of the dendron by ester linkage (Scheme 1). These esters can potentially be cleaved by pH-dependent or enzymatic hydrolysis to release the parent-active herbicide 2,4-D.
[0243]
[0244] In addition to PEG length and generation of dendrons, the rate of hydrolysis can also be controlled by utilizing ester linkages from primary or secondary hydroxyl groups. The synthesis of second and third generation dendrons with primary ester linkages is shown in Scheme 2.
[0245]
Embodiment 3
[0246] Example 3: Synthesis of Alternative Amphiphilic PEG-Dendron Hybrids (1a-1c)
[0247]
[0248] In the above scheme, MeO-PEG-NH 2 (Compounds 2a-2c) are represented by the structures shown in Scheme 4.
[0249] Amphiphilic hybrids (1a-c) of the present invention can be prepared by the process described above in General Scheme 3. Briefly, hybrid block copolymers were synthesized using monomethyl ether PEG-amines 2a–c as starting materials. Conjugation with active ester 3 of 3,5-bis(prop-2-yn-1-yloxy)benzoic acid generates PEG-diynes 4a-c. The latter were further modified by thiol-alkyne reaction with N-Boc cystamine 5 to give tetrafunctionalized PEG-dendrons 6a–c, followed by deprotection of Boc to generate PEG-tetramines 7a–c . In the final step of the synthesis, an enzymatically cleavable hydrophobic surface group was introduced using the agrochemical compound 8.
[0250] pass 1 H and 13 C-NMR, GPC, IR and MALDI were used to characterize the synthesized polymers...
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Abstract
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