Agro-Industrial Waste Valorization: Transformation of Starch from Mango Kernel into Biocompatible, Thermoresponsive and High Swelling Nanogels

Marlizia De Oliveira,Matt Kipper,Liszt Madruga,Rosangela Balaban,Men De Souza Filho,Bruna De Lima,Nívia Marques,Marcos Villetti

doi:10.21577/0103-5053.20210059

Abstract

Mango industry processing disposes 40-60% of this fruit as residues, such as peels and kernels. The exploration of bioproducts from these industrial rejects can reduce environmental impact besides of producing high value-added materials. In this scenario, carboxymethyl starch nanoparticles were produced from mango (Mangifera indica L.) kernel starch. These nanoparticles were then decorated with thermoresponsive chains of the amino terminated poly(N-isopropylacrylamide) (PNIPAM‑NH2), with the intention of evaluating their applicability in the biomedical area. Elemental analysis, Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopy confirmed successful grafting of PNIPAM-NH2 onto the carboxymethyl starch backbone. Scanning electron microscopy (SEM) images and dynamic light scattering (DLS) data showed sizes of 100 and 112 nm in the dry state and of 744 and 598 nm in the hydrated state, when the grafting degree (GD) was of 6 and 14.3%, respectively. The degree of swelling was of 41,100 and 15,100% for GD of 6 and 14.3% respectively, suggesting that the nanogels are suitable for drug incorporation. The toxicity of the nanogels to human adipose-derived stem cells (ADSCs) and red blood cells (RBCs) was evaluated by lactate dehydrogenase (LDH), alamarBlue and hemolysis assays. Both nanogels were non-cytotoxic and non-hemolytic, suggesting the suitability of these biomaterials for cell- and blood-contacting applications.

Highlights

The use of polysaccharides as matrices of nanogels in biomedical applications has been increasingly studied, as this strategy adds biologically favorable properties to the resulting materials.[1,2,3,4] Starch, for example, commonly found in wheat, corn, potato and cassava, is one of the polysaccharides most widely used in the pharmaceutical industry.In recent years, the increasing demand for starch in food and non-food related applications has encouragedThe introduction of thermoresponsive polymers with a lower critical solution (LCST) onto the polysaccharide structure promotes the formation of derivatives with improved properties when compared to unmodifiedAgro-Industrial Waste ValorizationJ
The introduction of PNIPAM chains onto carboxymethyl starch (CMS) was indicated by the presence of nitrogen in CMS-gPNIPAM1 and CMS-g-PNIPAM2.32 with the increase in the feed amount of PNIPAM-NH2, the percentages of C, H and N were increased, suggesting a higher grafting degree for CMS-g-PNIPAM2 than for CMS-g-PNIPAM1
In addition to the aforementioned starch peaks, the Fourier-transform infrared spectroscopy (FTIR) spectra of the copolymers exhibit the characteristic peaks of PNIPAM: at 1626 cm-1, due to C=O stretching; at 1530 cm-1, ascribed to N-H stretching; and at 1371 and 1366 cm-1, corresponding to the symmetric bend of isopropyl groups

Summary

Introduction

The use of polysaccharides as matrices of nanogels in biomedical applications has been increasingly studied, as this strategy adds biologically favorable properties to the resulting materials.[1,2,3,4] Starch, for example, commonly found in wheat, corn, potato and cassava, is one of the polysaccharides most widely used in the pharmaceutical industry.In recent years, the increasing demand for starch in food and non-food related applications has encouragedThe introduction of thermoresponsive polymers with a lower critical solution (LCST) onto the polysaccharide structure promotes the formation of derivatives with improved properties when compared to unmodifiedAgro-Industrial Waste ValorizationJ. The degree of swelling, thermoresponsive properties and the biocompatibility of the nanogels towards human adipose-derived stem cells (ADSCs) and red blood cells (RBCs) were investigated.

Results

Conclusion