Integrating Cellulose Microfibrils and Ellagitannins from Rambutan Peel with Gelatin for Production of Synergistic Biobased Hydrogels

Abstract

The pursuit of renewable and eco-friendly raw materials for biobased materials is a growing field. This study utilized ellagitannin and cellulose microfibrils derived from rambutan peel waste alongside gelatin to develop eco-conscious hydrogels. The cellulose/gelatin hydrogels were formulated in two weight ratios (0.5:1 to 1:1), and the influence of gelatin on the chemical composition and rheology was studied. Composite hydrogels, functionalized with an ellagitannin-rich extract, exhibited a remarkable enhancement of up to 14-fold in compressive strength. The hydrogels also demonstrated antimicrobial properties, reducing the Staphylococcus aureus colony count within 24 h. The hydrogel, derived from rambutan peel waste, is biocompatible and could potentially be explored for biomedical applications such as drug delivery systems, and wound dressings. This suggests that it might offer significant value for sustainable materials science, although specific applications have yet to be tested.

Figure 1

Schematic of the hydrogel preparation. Rambutan peel (A) is first separated into an ellagitannin and cellulose fiber fraction. The latter is bleached and processed into cellulose microfibrils (B). After the addition of gelatin, self-standing hydrogels are formed (C), which are postfunctionalized with the ellagitannin-rich extractive (D).

Figure 2

Microscopic morphology of bleached cellulose fibers from rambutan peel after various blending times, displayed at 10× magnification.

Figure 3

Rheological behavior of hydrogels: A) viscosity curves and B) frequency sweeps of cellulose microfibrils from rambutan peel (Cell), gelatin (Gel), and CMF/gelatin composites (Cell/Gel_0.5 and Cell/Gel_1).

Figure 4

Elemental mapping in cellulose- and gelatin-based hydrogels with or without ellagitannin: Carbon (red), oxygen (green), nitrogen (blue), and mixed image overlaying all elemental distributions in the hydrogel.

Figure 5

(A) Images of cellulose/gelatin hydrogels Cell/gel of different cellulose/gelatin mass ratios and reference (Cell). (B) Infrared spectra of the samples.

Figure 6

(A) Images of ellagitannin-reinforced cellulose/gelatin E-Cell/Gel and cellulose microfibril (E-Cell) hydrogels. Compression test of hydrogels (B) in native state and (C) functionalized with the ellagitannin-rich Rambutan peel extract.

Figure 7

WAXS diffraction patterns (ellagitannin-reinforced cellulose (A), cellulose/gelatin (B,C) hydrogels) showing ellagitannin-reinforced cellulose hydrogels’ crystalline and amorphous domains with varying gelatin concentrations and their associated crystallinity indices (D).

Figure 8

Pictures of cultivated S. aureus colonies on Mueller Hinton agar for 24 h; (A) control, (B) E-Cell, (C) E-Cell/Gel_0.5, and (D) E-Cell/Gel_1. The numbers denote the colony-forming units (CFUs) of each sample.

Figure 9

Metabolic activity for L929 cells cultured with ellagitannin-containing hydrogels and those cultured with only the culture media (control) expressed as the percentage cell viability.