The oral delivery of peptides and proteins is an active research field despite the various challenges limiting their efficient delivery. The oral route of drug administration is the most common route associated with high patient safety and compliance. However, most protein/peptides therapeutics are delivered by the invasive parenteral route due to their large molecular size, liability to degradation and limited absorption in the gastrointestinal tract. Therefore, incorporating nanotechnology tools into the delivery systems, that can protect encapsulated therapeutics protein/peptides from gastric degradation and enhance their permeation through the intestinal mucosal, is essential to accomplish high oral bioavailability acceptable in clinical administrations. Recently, gold nanoparticles (AuNPs) have gained much attention as interesting drug delivery platforms, due to their surface properties that facilitate the attachment of therapeutic molecules and target compounds, their nano range size enabling them to cross cells, and their apparent low toxicity. Potentially, therapeutic protein/peptides intestinal instability can be overcome by coating AuNPs with the xylan polysaccharide. Xylan cannot be digested in the stomach but is degradable by enzymes produced by the colonic microbiota. Thus, the systems prepared with xylan as excipient aim to achieve protection of oral drug delivery carriers from the harsh gastric environment. The present work is purposed at developing xylan coated gold nanoparticles (Xylan-AuNPs), intended to encapsulate therapeutic protein /peptides within their structure and serve as unique therapeutic-protein oral drug-delivery vehicles, that have the ability to respond to ambient changes in pH, through the gastrointestinal tract (GIT). The influence of xylan from different sources wheat arabinoxylan, beechwood xylan and concentrations at various pH values on the formation of xylan- gold nanoparticles was assessed by measuring the Z-average nanoparticle size using the dynamic light scattering technique. In addition, the optical properties of nanoparticles were analysed by a UV-VIS spectrophotometer. The results have demonstrated the feasibility of using wheat arabinoxylan excipient to coat and protect gold nanoparticles particles at low pH values that mimic the stomach environment. Specifically, wheat arabinoxylan 0.001%(w/v) concentration at pH 2.2 was shown to be the most suitable concentration to coat the gold nanoparticle without aggregation. Such systems may be very promising for emerging nanomedicines and protein oral delivery systems. Moreover, use of gold nanoparticles with beechwood xylan has not shown any notable alterations in coatings. In addition, aggregate formation was detected.
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