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Hussain, A, Pina AS, Roque ACA.  2009.  Bio-recognition and detection using liquid crystals. Biosensors and Bioelectronics. 25:1–8., Number 1 AbstractWebsite

Liquid crystals {(LCs)} are used extensively by the electronics industry as display devices. Advances in the understanding of the liquid crystalline phase and the chemistry therein lead to the development of {LC} exhibiting faster switching speed with greater twist angle. This in turn lead to the emergence of liquid crystal displays, rendering dial-and-needle based displays (such as those used in various meters) and cathode ray tubes obsolete. In this article, we review the history of {LC} and their emergence as an invaluable material for display devices and the more recent discovery of their use as sensing elements in biosensors. This new application of {LC} as tools in the development of fast and simple biosensors is envisaged to gain more importance in the foreseeable future.

Fernandes, CSM, Gonçalves B, Sousa M, Martins DL, Barroso T, Pina AS, Peixoto C, Aguiar-Ricardo A, Roque ACA.  2015.  Biobased Monoliths for Adenovirus Purification. ACS Applied Materials & Interfaces. 7(12):6605-6612., Number 12 AbstractWebsite

Adenoviruses are important platforms for vaccine development and vectors for gene therapy, increasing the demand for high titers of purified viral preparations. Monoliths are macroporous supports regarded as ideal for the purification of macromolecular complexes, including viral particles. Although common monoliths are based on synthetic polymers as methacrylates, we explored the potential of biopolymers processed by clean technologies to produce monoliths for adenovirus purification. Such an approach enables the development of disposable and biodegradable matrices for bioprocessing. A total of 20 monoliths were produced from different biopolymers (chitosan, agarose, and dextran), employing two distinct temperatures during the freezing process (−20 °C and −80 °C). The morphological and physical properties of the structures were thoroughly characterized. The monoliths presenting higher robustness and permeability rates were further analyzed for the nonspecific binding of Adenovirus serotype 5 (Ad5) preparations. The matrices presenting lower nonspecific Ad5 binding were further functionalized with quaternary amine anion-exchange ligand glycidyltrimethylammonium chloride hydrochloride by two distinct methods, and their performance toward Ad5 purification was assessed. The monolith composed of chitosan and poly(vinyl) alcohol (50:50) prepared at −80 °C allowed 100% recovery of Ad5 particles bound to the support. This is the first report of the successful purification of adenovirus using monoliths obtained from biopolymers processed by clean technologies.

Roque, ACA, Bicho A, Batalha IL, Cardoso AS, Hussain A.  2009.  Biocompatible and bioactive gum Arabic coated iron oxide magnetic nanoparticles. Journal of Biotechnology. 144:313–320., Number 4 AbstractWebsite

The surface modification of iron oxide magnetic nanoparticles {(MNPs)} with gum Arabic {(GA)} via adsorption and covalent coupling was studied. The adsorption of {GA} was assessed during {MNP} chemical synthesis by the co-precipitation method {(MNP\_GA)}, and after {MNP} synthesis on both bare magnetite and {MNP\_GA.} The covalent immobilization of {GA} at the surface of aldehyde-activated {(MNP\_GAAPTES)} or aminated {MNPs} {(MNP\_GAEDC)} was achieved through free terminal amino and carboxylate groups from {GA.} The presence of {GA} at the surface of the {MNPs} was confirmed by {FTIR} and by the quantification of {GA} by the bicinchoninic acid test. Results indicated that the maximum of {GA} coating was obtained for the covalent coupling of {GA} through its free carboxylate groups {(MNP\_GAEDC)}, yielding a maximum of 1.8&\#xa0;g of {GA} bound/g of dried particles. The hydrodynamic diameter of {MNPs} modified with {GA} after synthesis resulted in the lowest values, in opposition to the {MNPs} co-precipitated with {GA} which presented the tendency to form larger aggregates of up to 1&\#xa0;μm. The zeta potentials indicate the existence of negatively charged surfaces before and after {GA} coating. The potential of the {GA} coated {MNPs} for further biomolecule attachment was assessed through anchorage of a model antibody to aldehyde-functionalized {MNP\_GA} and its subsequent detection with an {FITC} labeled anti-antibody.

Barroso, T, Roque ACA, Aguiar-Ricardo A.  2012.  Bioinspired and Sustainable Chitosan Based Monoliths for Antibody Capture and Release. RSC ADV. 2(30):11285-11294. AbstractWebsite

Chitosan-based monoliths activated by plasma technology induced the coupling of a robust biomimetic ligand, previously reported as an artificial Protein A, with high yields while minimizing the environmental impact of the procedure. Due to the high porosity, good mechanical and tunable physicochemical properties of the affinity chitosan-based monoliths, it is possible to achieve high binding capacities (150 ± 10 mg antibody per gram support), and to recover 90 ± 5% of the bound protein with 98% purity directly from cell-culture extracts. Therefore, the chitosan-based monoliths prepared by clean processes exhibit a remarkable performance for the one-step capture and recovery of pure antibodies or other biological molecules with biopharmaceutical relevance.

Dias, AMGC, Hussain A, Marcos AS, Roque ACA.  2011.  A biotechnological perspective on the application of iron oxide magnetic colloids modified with polysaccharides. Biotechnology Advances. 29:142–155., Number 1 AbstractWebsite

Iron oxide magnetic nanoparticles {(MNPs)} alone are suitable for a broad spectrum of applications, but the low stability and heterogeneous size distribution in aqueous medium represent major setbacks. These setbacks can however be reduced or diminished through the coating of {MNPs} with various polymers, especially biopolymers such as polysaccharides. Polysaccharides are biocompatible, non-toxic and renewable; in addition, they possess chemical groups that permit further functionalization of the {MNPs.} Multifunctional entities can be created through decoration with specific molecules e.g. proteins, peptides, drugs, antibodies, biomimetic ligands, transfection agents, cells, and other ligands. This development opens a whole range of applications for iron oxide nanoparticles. In this review the properties of magnetic structures composed of {MNPs} and several polysaccharides {(Agarose}, Alginate, Carrageenan, Chitosan, Dextran, Heparin, Gum Arabic, Pullulan and Starch) will be discussed, in view of their recent and future biomedical and biotechnological applications.

Dhadge, VL, Hussain A, Azevedo AM, Aires-Barros MR, Roque ACA.  2014.  Boronic acid-modified magnetic materials for antibody purification. J. R. Soc. Interface. 11(91):20130875. AbstractWebsite

Aminophenyl boronic acids can form reversible covalent ester interactions with cis-diol-containing molecules, serving as a selective tool for binding glycoproteins as antibody molecules that possess oligosaccharides in both the Fv and Fc regions. In this study, amino phenyl boronic acid (APBA) magnetic particles (MPs) were applied for the magnetic separation of antibody molecules. Iron oxide MPs were firstly coated with dextran to avoid non-specific binding and then with 3-glycidyloxypropyl trimethoxysilane to allow further covalent coupling of APBA (APBA_MP). When contacted with pure protein solutions of human IgG (hIgG) and bovine serum albumin (BSA), APBA_MP bound 170 ± 10 mg hIgG g−1 MP and eluted 160 ± 5 mg hIgG g−1 MP, while binding only 15 ± 5 mg BSA g−1 MP. The affinity constant for the interaction between hIgG and APBA_MP was estimated as 4.9 × 105 M−1 (Ka) with a theoretical maximum capacity of 492 mg hIgG adsorbed g−1 MP (Qmax), whereas control particles bound a negligible amount of hIgG and presented an estimated theoretical maximum capacity of 3.1 mg hIgG adsorbed g−1 MP (Qmax). APBA_MPs were also tested for antibody purification directly from CHO cell supernatants. The particles were able to bind 98% of IgG loaded and to recover 95% of pure IgG (purity greater than 98%) at extremely mild conditions.