Shiga toxin (Stx) is the main virulence factor of Shiga toxin-producing Escherichia coli (STEC) bacterial strains. STEC are transmitted to humans by contaminated food, water, person-to-person contact, and direct exposure to farm animals. There are two different types of Stx: Stx1 and Stx2 with its variants, being Stx2 clinically more relevant [1]. Stx2 gains access to the bloodstream after STEC bowel infection, reaching different organs, including the kidneys and brain, and is responsible for the development of a systemic disease known as hemolytic uremic syndrome (HUS). HUS is characterized by hemolytic anemia, thrombocytopenia, and acute kidney injury and affects mostly children under five years old [2,3]. Nowadays, no specific treatment nor rapid and early diagnostic tool is available for clinicians. Thus, HUS treatment relies on supportive care, including; fluid volume management, hypertension control, and correction of electrolyte abnormalities [4]. However, several experimental efforts regarding the treatment and early diagnosis of STEC-HUS have been explored. In this regard, one potential therapeutic approach for HUS treatment is to neutralize circulating Stx2 with specific anti-Stx2 antibodies (IgG-Stx2) or compounds [5,6]. Moreover, monoclonal or polyclonal-specific antibody approaches were assayed, and clinical trials were performed [[7], [8], [9], [10]]. Antibodies, including polyclonal and monoclonal IgG, Fab, scFv, and nanobodies can be powerful biotherapeutics for autoimmune, cardiovascular, cancer and infectious diseases [11]. The neutralization properties of antibodies were explored to neutralize toxins, viruses, and other molecules for therapeutics. The advantages of antibody-based therapies for infectious diseases include versatility and pathogen specificity. However, some functional limitations of therapeutic antibodies have come to light such as high costs of production in the case of engineered antibodies, inadequate pharmacokinetics, and tissue accessibility as well as impaired interactions with the immune system [12]. In this line of action, our group demonstrated that, IgG purified from hyperimmune bovine colostrum against Stx2 was able to neutralize STEC pathogenicity in vitro and in vivo models [13]. The limited knowledge about when Stx enters the bloodstream and Stx levels in infected tissues and blood, makes the timing of IgG-Stx2 administration and its half-life critical for success [14]. Thus, increasing the half-life of the antibody or the avidity may decrease toxicity and adverse effects. In this sense, polymeric nanomicelles have emerged over the last years as highly promising platforms due to their high half-life in blood circulation, relatively high tissue penetrability, high capacity to effectively overcome biological barriers, and manageable toxicity [[15], [16], [17]]. Soluplus®, a polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PVCL-PVA-PEG), is a novel excipient that enhances the oral bioavailability of poorly soluble drugs [18]. Soluplus® nanomicelles (NM) have a core-shell structure that can encapsulate hydrophobic molecules in the inner core and load hydrophilic molecules in the outer layer [19]. NM possess a unique nanoscopic architecture and small size (usually ranging from 10 to 100 nm), making it an ideal material for drug delivery systems. It has the potential to protect the payload from drug degradation, provide controlled and sustained drug release, decrease clearance, enhance stability, and improve drug accumulation in diseased tissues. These properties make NM highly suitable for drug delivery applications [20,21].

Association of specific IgG with a nanoplatform may improve avidity, optimize pharmacokinetics and pharmacodynamics, reduce side effects, and improve the therapeutic efficacy of the antibody. Also, this platform may give the possibility of combining antibodies against different epitopes and molecules, the internalization into target cells, provide longer bioavailability and the option to use them as carriers of lipophilic drugs [[22], [23], [24], [25]]. We propose that using nanotechnology-based carriers could be a promising approach for delivering IgG-Stx2 in therapeutic or diagnostic strategies. Therefore, our goal was to develop and characterize NM associated with IgG-Stx2 (NM-IgG-Stx2) and investigate its advantages and applicability in recognizing and neutralizing Stx2.