Amylose is carbohydrate polymer defined as a linear natural polysaccharide composed of α(1→4) bound glucose units. Due to its abundance, renewable nature, low cost, and biodegradability, this polymer is regarded as a promising green material for producing crystals and particles of different sizes ranging from the nanometer scale to the micrometer scale. Herein, short amylose chains and dextran-coated iron oxide magnetic nanoparticles (Dex@IONPs) were introduced to fabricate well-dispersed starch magnetic microbeads (SMMBs), which have a well-defined spherical shape and a uniform size of about 1 μm. We found that the aggregation of SMMBs can be mediated by the introduced Dex@IONPs in a concentration-dependent manner, indicating that Dex@MNPs, as the seed crystals, play an important role in self-assembly of SMMBSs. By using streptococcal protein G tagged with maltose binding protein (MBP-SPG), specific antibody against Escherichia coli O157:H7 was successfully immobilized on the surface of SMMBs. The Ab-functionalized SMMBs showed a high capture efficiency (>90%) comparable to the commercial immunomagnetic microparticles regardless of suspending agents (1X PBS and milk). Moreover, SMMBs exhibited excellent recyclability, in which the Ab immobilized on the surface of SMMBs can be refreshed by using the maltose elution buffer along with the unchanged capture efficiency. In addition, SMMBSs were assembled into the linear rod-shape microstructure by the introduced magnetic field during the amylose-mediated precipitation process. The convenient self-assembly of SMMBs with the well-defined size and shape, biocompatibility, tolerance to environmental variances, high magnetic response behavior, and excellent recyclability in the functionalization make these magnetic microparticles promising for many potential applications such as bio-sensing, labeling, and smart delivery of active compounds.

The outbreaks of foodborne diseases associated with bacterial contamination are still critical issues all over the world. To ensure food safety, the diagnosis of pathogenic bacteria on site at early state of contamination are required. Escherichia coli O157:H7 (E. Coli O157:H7) is one of the major factor causing foodborne diseases. We introduce a sandwich type colorimetric detection method integrated with chitosan-coated starch magnetic polymer beads(CS@SMBs) that can separate and concentrate bacteria in aqueous environment. For signal amplification, horseradish peroxidase-conjugated antibody (HRP-Antibody) and 3,3',5,5'- tetramethylbenzidine (TMB) were employed as enzyme label and chromogenic substrate, respectively. We demonstrate that CS@SMBs not only show a good magnetic sensitivity, but also can capture a variety of bacteria regardless of Gram-negative and Gram-positive, which offer possibility for separation of the broad range of bacteria from food matrix. Our approach successfully captures E. coli O157:H7 with detection limit of 101 CFU/mL through naked eye, making promise of fast, on-site, and sensitive detection of pathogenic bacteria.

Starch is an abundant, renewable, and low cost material that has been extensively studied for its role in crystallization. Herein, we developed a facile and green approach to produce the starch-based microparticles (SMPs) that could encapsulate curcumin during the self-association of short glucan chain obtained from waxy maize starch. Scanning electron microscopy (SEM) analysis indicated that the diameters of curcumin-loaded SMPs were ranged from 1.5 μm to 3 μm. The characteristics of the curcumin-loaded SMPs were evaluated via Raman spectroscopy, confocal microscopy, UV spectrophotometer, and X-ray diffraction (XRD). The results showed that the suspended curcumin was encapsulated in SMPs in amorphous form with a encapsulating efficiency of about 96.36%. Photostability test confirmed that curcumin that is loaded inside SMPs was effectively protected against the photodegradation. Curcumin-loaded SMPs can be used not only in food industry for extending the shelf life of curcumin, but also in pharmaceutical industry to design effective carrier for oral delivery.

Vitamin A is essential for growth and differentiation of a number of cells and tissues, as result the precursor, a carotenoid β-carotene remains their essential source of vitamin A. However, the major problem this carotenoid face, is its susceptible to photodegradation and chemical oxidation, those properties make it difficult to use as an ingredient as functional food product and reduce its bioavailability. This study presents a novel approach to prepare a one-step inclusion complex using amylose microparticles as host molecule using amylosucrase from Deinococcus geothermalis (DGAS) and β-carotene nanoparticles, which were added into the DGAS enzyme reaction solution to entrap them during the synthesis of amylose chains. HRFE-SEM showing a spherical shape and average diameter of 4-8 μm; XRD and DSC showed an amorphous structure as well as less energy required to start the gelatinization process, due to the complexation of amylose chains with the β-carotene nano dispersion. Last but not least Raman spectroscopy was performed in order to confirmed the complex formation between β-carotene and amylose microparticles, showing the characteristic peaks of both compound. The stability test in this study showed the high stability of the complexed microparticles against environmental stresses such as, photodegradation and chemical oxidation. We expect this study contributes to the development of functional food materials to enhance the stability and bioavailability of active compounds.