Preparation of novel immunomagnetic cellulose microspheres via cellulose binding domain-protein A linkage and its use for the isolation of interferon alpha-2b

Filter paper disks as a matrix for manipulation of recombinant proteins

Filter paper provides an excellent matrix for retention of proteins containing a cellulose binding domain. To use this capability for manipulating recombinant fusion proteins, binding and elution parameters were explored and procedures developed for small scale purification, modification and assay. Proteins were tagged with the cellulose binding domain from the Clostridium thermocellum CipB gene via a cleavable linker. Filter paper disks of 6 mm diameter were able to bind up to 80 μg protein although there was a substantial dependence on molecular size. Different means of introducing fusion proteins to the disks allow either binding within 20 min from microliter volumes or slower binding from milliliter volumes. Elution with protease in small volumes yielded greater than 10 μg amounts with concentrations in the 1-2 mg/ml range. To demonstrate their utility, disks were used for small scale protein purification, covalent modification of protein, immunoprecipitation, and in a binding assay. These versatile methods allow parallel processing of multiple samples and may find many uses when only small amounts of protein are needed.

Progress in affinity ligand-functionalized bacterial magnetosome nanoparticles for bio-immunomagnetic separation of HBsAg protein

Efficient Bio-immunomagnetic separation (BIMS) of recombinant hepatitis B surface antigen (rHBsAg) with high binding capacity was studied using affinity ligand immobilized bacterial magnetosome nanoparticles (Magnetospirillum gryphiswaldense strain MSR-1 bacteria) as an immunomagnetic sorbent. Our results showed immunomagnetic adsorption, acted by affinity interactions with the immobilized monoclonal antibody, offered higher antigen adsorption and desorption capacities as compared with the commercially available immunoaffinity sorbents. Four different ligand densities of the Hep-1 monoclonal antibody were examined during covalent immobilization on Pyridyl Disulfide-functionalized magnetosome nanoparticles for HBsAg immunomagnetic separation. The average of adsorption capacity was measured as 3 mg/ml in optimized immunomagnetic sorbent (1.056 mg rHBsAg/ml immunomagneticsorbent/5.5 mg of total purified protein) and 5mg/ml in immunoaffinity sorbent (0.876 mg rHBsAg/ml immunosorbent/5.5 mg total purified protein during 8 runs. Immunomagnetic sorbent demonstrated ligand leakage levels below 3 ng Mab/Ag rHBsAg during 12 consecutive cycles of immunomagnetic separation (IMS). The results suggest that an immunomagnetic sorbent with a lower ligand density (LD = 3 mg Mab/ml matrix) could be the best substitute for the immunosorbent used in affinity purification of r-HBsAg there are significant differences in the ligand density (98.59% (p-value = 0.0182)), adsorption capacity (97.051% (p-value = 0.01834)), desorption capacity (96.06% (p-value = 0.036)) and recovery (98.97% (p-value = 0.0231)). This study indicates that the immunosorbent approach reduces the cost of purification of Hep-1 protein up to 50% as compared with 5 mg Mab/ml immunoaffinity sorbent, which is currently used in large-scale production. As well, these results demonstrate that bacterial magnetosome nanoparticles (BMs) represent a promising alternative product for the economical and efficient immobilization of proteins and the immunomagnetic separation of Biomolecules, promoting innovation in downstream processing.

Mechanism of antibodies purification by protein A

Protein A, a major cell wall component of Staphylococcus aureus, is one of the first immunoglobulin-binding proteins that is discovered about 80 years ago. However, a great deal of development in both purification methods and application of antibodies in treatment have been done. There are many publications based on the untargeted (size exclusion, ion exchange and hydrophobic interactions) and targeted (affinity) methods by scientists in academic/industry groups. In this review, we have focused on the study of both native and engineered Protein A to understand its mechanism in the purification of antibodies. What domain of Protein A dose interact with antibody? Where are contact regions? What is the non-covalent interaction mechanism of Protein A and antibody? Does alkaline condition, in the washing step, influence on antibody structure and activity? On the other hand, the immobilization of Protein A on various sorbents such as agarose, silica, polysaccharide, polymers, and magnetic nanoparticles have investigated. Also, the application of Protein A as biosensor for detection of the antibody is discussed. We have tried to find interesting and stimulating answers to all these questions.

A biomolecular recognition approach for the functionalization of cellulose with gold nanoparticles

Materials with new and improved functionalities can be obtained by modifying cellulose with gold nanoparticles (AuNPs) via the in situ reduction of a gold precursor or the deposition or covalent immobilization of pre-synthesized AuNPs. Here, we present an alternative biomolecular recognition approach to functionalize cellulose with biotin-AuNPs that relies on a complex of 2 recognition elements: a ZZ-CBM3 fusion that combines a carbohydrate-binding module (CBM) with the ZZ fragment of the staphylococcal protein A and an anti-biotin antibody. Paper and cellulose microparticles with AuNPs immobilized via the ZZ-CBM3:anti-biotin IgG supramolecular complex displayed an intense red color, whereas essentially no color was detected when AuNPs were deposited over the unmodified materials. Scanning electron microscopy analysis revealed a homogeneous distribution of AuNPs when immobilized via ZZ-CBM3:anti-biotin IgG complexes and aggregation of AuNPs when deposited over paper, suggesting that color differences are due to interparticle plasmon coupling effects. The approach could be used to functionalize paper substrates and cellulose nanocrystals with AuNPs. More important, however, is the fact that the occurrence of a biomolecular recognition event between the CBM-immobilized antibody and its specific, AuNP-conjugated antigen is signaled by red color. This opens up the way for the development of simple and straightforward paper/cellulose-based tests where detection of a target analyte can be made by direct use of color signaling.

Stability and Ligand Promiscuity of Type A Carbohydrate-binding Modules Are Illustrated by the Structure of Spirochaeta thermophila StCBM64C

Deconstruction of cellulose, the most abundant plant cell wall polysaccharide, requires the cooperative activity of a large repertoire of microbial enzymes. Modular cellulases contain non-catalytic type A carbohydrate-binding modules (CBMs) that specifically bind to the crystalline regions of cellulose, thus promoting enzyme efficacy through proximity and targeting effects. Although type A CBMs play a critical role in cellulose recycling, their mechanism of action remains poorly understood. Here we produced a library of recombinant CBMs representative of the known diversity of type A modules. The binding properties of 40 CBMs, in fusion with an N-terminal GFP domain, revealed that type A CBMs possess the ability to recognize different crystalline forms of cellulose and chitin over a wide range of temperatures, pH levels, and ionic strengths. A Spirochaeta thermophila CBM64, in particular, displayed plasticity in its capacity to bind both crystalline and soluble carbohydrates under a wide range of extreme conditions. The structure of S. thermophila StCBM64C revealed an untwisted, flat, carbohydrate-binding interface comprising the side chains of four tryptophan residues in a co-planar linear arrangement. Significantly, two highly conserved asparagine side chains, each one located between two tryptophan residues, are critical to insoluble and soluble glucan recognition but not to bind xyloglucan. Thus, CBM64 compact structure and its extended and versatile ligand interacting platform illustrate how type A CBMs target their appended plant cell wall-degrading enzymes to a diversity of recalcitrant carbohydrates under a wide range of environmental conditions.

Immunoaffinity Chromatography: Concepts and Applications

Antibody-based separation methods, such as immunoaffinity chromatography (IAC), are powerful purification and isolation techniques. Antibodies isolated using these techniques have proven highly efficient in applications ranging from clinical diagnostics to environmental monitoring. Immunoaffinity chromatography is an efficient antibody separation method which exploits the binding efficiency of a ligand to an antibody. Essential to the successful design of any IAC platform is the optimization of critical experimental parameters such as (a) the biological affinity pair, (b) the matrix support, (c) the immobilization coupling chemistry, and (d) the effective elution conditions. These elements and the practicalities of their use are discussed in detail in this review. At the core of all IAC platforms is the high affinity interactions between antibodies and their related ligands; hence, this review entails a brief introduction to the generation of antibodies for use in immunoaffinity chromatography and also provides specific examples of their potential applications.

Fluorescence correlation spectroscopy study of the complexation of DNA hybrids, IgG antibody, and a chimeric protein of IgG-binding ZZ domains fused with a carbohydrate binding module

Fluorescence correlation spectroscopy (FCS) was used to characterize the molecular interactions between the four components of a DNA recognition system.

On the subtle tuneability of cellulose hydrogels: implications for binding of biomolecules demonstrated for CBM 1

Choice of molecular probe for determining porosity, surface area, or binding in never-dried cellulose hydrogels is critical to discern differences in structure.

Capture and detection of DNA hybrids on paper via the anchoring of antibodies with fusions of carbohydrate binding modules and ZZ-domains

Microfluidic paper-based analytical devices (μPADs) fabricated by wax-printing are suitable platforms for the development of simple and affordable molecular diagnostic assays for infectious diseases, especially in resource-limited settings. Paper devices can be modified for biological assays by adding appropriate reagents to the test areas. For this purpose, the use of affinity immobilization strategies can be a good solution for bioactive paper fabrication. This paper describes a methodology to capture labeled-DNA strands and hybrids on paper via the anchoring of antibodies with a fusion protein that combines a family 3 carbohydrate binding module (CBM) from Clostridium thermocellum, with high affinity to cellulose, and the ZZ fragment of the staphyloccocal protein A, which recognizes IgG antibodies via their Fc portion. Antibodies immobilized via CBM-ZZ were able to capture appropriately labeled (biotin, fluorescein) DNA strands and DNA hybrids. The ability of an antibody specific to biotin to discriminate complementary from noncomplementary, biotin-labeled targets was demonstrated in both spot and microchannel assays. Hybridization was detected by fluorescence emission of the fluorescein-labeled DNA probe. The efficiency of the capture of labeled-DNA by antibodies immobilized on paper via the CBM-ZZ construct was significantly higher when compared with a physical adsorption method where antibodies were simply spotted on paper without the intermediation of other molecules. The experimental proof of concept of wax-printed μPADs functionalized with CBM-ZZ for DNA detection at room temperature presented in this study constitutes an important step toward the development of easy to use and affordable molecular diagnostic tests.

Cellulose: from biocompatible to bioactive material

The immobilization of biomolecules onto cellulose paper turns this environmentally friendly material into a platform for diagnostic devices.

Plant viral vectors for delivery by Agrobacterium

Plant viral vectors delivered by Agrobacterium are the basis of several manufacturing processes that are currently in use for producing a wide range of proteins for multiple applications, including vaccine antigens, antibodies, protein nanoparticles such as virus-like particles (VLPs), and other protein and protein-RNA scaffolds. Viral vectors delivered by agrobacterial T-DNA transfer (magnifection) have also become important tools in research. In recent years, essential advances have been made both in the development of second-generation vectors designed using the 'deconstructed virus' approach, as well as in the development of upstream manufacturing processes that are robust and fully scalable. The strategy relies on Agrobacterium as a vector to deliver DNA copies of one or more viral RNA/DNA replicons; the bacteria are delivered into leaves by vacuum infiltration, and the viral machinery takes over from the point of T-DNA transfer to the plant cell nucleus, driving massive RNA and protein production and, if required, cell-to-cell spread of the replicons. Among the most often used viral backbones are those of the RNA viruses Tobacco mosaic virus (TMV), Potato virus X (PVX) and Cowpea mosaic virus (CPMV), and the DNA geminivirus Bean yellow dwarf virus. Prototypes of industrial processes that provide for high yield, rapid scale up and fast manufacturing cycles have been designed, and several GMP-compliant and GMP-certified manufacturing facilities are in place. These efforts have been successful as evidenced by the fact that several antibodies and vaccine antigens produced by magnifection are currently in clinical development.

Immunoaffinity chromatography

Antibody-based separation methods, such as immunoaffinity chromatography (IAC), are powerful purification and isolation techniques. Antibodies isolated using these techniques have proven highly efficient in applications ranging from clinical diagnostics to environmental monitoring. IAC is an efficient antibody separation method which exploits the binding efficiency of a ligand to an antibody. Essential to the successful design of any IAC platform is the optimisation of critical experimental parameters such as: (a) the biological affinity pair, (b) the matrix support, (c) the immobilisation coupling chemistry, and (d) the effective elution conditions. These elements and the practicalities of their use are discussed in detail in this review. At the core of all IAC platforms is the high-affinity interactions between antibodies and their related ligands; hence, this review entails a brief introduction to the generation of antibodies for use in IAC and also provides specific examples of their potential applications.

Control of protein immobilization: coupling immobilization and site-directed mutagenesis to improve biocatalyst or biosensor performance

Mutagenesis and immobilization are usually considered to be unrelated techniques with potential applications to improve protein properties. However, there are several reports showing that the use of site-directed mutagenesis to improve enzyme properties directly, but also how enzymes are immobilized on a support, can be a powerful tool to improve the properties of immobilized biomolecules for use as biosensors or biocatalysts. Standard immobilizations are not fully random processes, but the protein orientation may be difficult to alter. Initially, most efforts using this idea were addressed towards controlling the orientation of the enzyme on the immobilization support, in many cases to facilitate electron transfer from the support to the enzyme in redox biosensors. Usually, Cys residues are used to directly immobilize the protein on a support that contains disulfide groups or that is made from gold. There are also some examples using His in the target areas of the protein and using supports modified with immobilized metal chelates and other tags (e.g., using immobilized antibodies). Furthermore, site-directed mutagenesis to control immobilization is useful for improving the activity, the stability and even the selectivity of the immobilized protein, for example, via site-directed rigidification of selected areas of the protein. Initially, only Cys and disulfide supports were employed, but other supports with higher potential to give multipoint covalent attachment are being employed (e.g., glyoxyl or epoxy-disulfide supports). The advances in support design and the deeper knowledge of the mechanisms of enzyme-support interactions have permitted exploration of the possibilities of the coupled use of site-directed mutagenesis and immobilization in a new way. This paper intends to review some of the advances and possibilities that these coupled strategies permit.

Preparation of cellulose magnetic microspheres with "the smallest critical size" and their application for microbial immunocapture

The goal of this paper is to introduce a universal method for quantitative control of the particle size of magnetic cellulose microspheres (MCMS) and to produce an optimal antibody absorption capability as an aid in the research of new applications of MCMS in immunomagnetic capture. In this study, "the smallest critical size theory" (TSCS) was proposed, tested, and confirmed by IgG-carrying capability measurements, magnetic response analysis, immunomagnetic capture, and PCR identification of bacteria. A Gaussian expression was proposed and used to guide the preparation of MCMS of the smallest critical size (SCS). The results showed that the diameter of the SCS of MCMS in this study was 5.82 mum, while the IgG absorption capability of the MCMS with SCS was 186.8 mg/mL. In addition, its high sensitivity and the efficiency of immunomagnetic capture of Salmonella bacteria exhibited another new application for MCMS.

Purification of plant-derived antibodies through direct immobilization of affinity ligands on cellulose

Plants possess enormous potential as factories for the large scale production of therapeutic reagents such as recombinant proteins and antibodies. A major factor limiting commercial advances of plant-derived pharmaceuticals is the cost and inefficiency of purification. As a model system, we have developed a simple yet robust method for immobilizing affinity capture ligands onto solid supports by interfacing the secreted expression and coupling of a chimeric fusion protein in Pichia pastoris to microcrystalline cellulose in a single step. The fusion protein, which consisted of antibody-binding proteins L and G fused to a cellulose-binding domain (LG-CBD), was tethered directly onto cellulose resins added to P. pastoris cultures and subsequently used for antibody purification. Both the antibody-binding protein L and protein G domains were functional, as demonstrated by the ability of cellulose-immobilized LG-CBD to purify both a scFv antibody fragment from yeast and a human IgG1 monoclonal antibody from transgenic tobacco. Furthermore, combining two P. pastoris strains expressing LG-CBD and scFv with CP-102 cellulose in a single culture allowed for easy recovery of biologically active scFv. Direct immobilization of affinity purification ligands, such as LG-CBD, onto inexpensive support matrices such as cellulose is an effective method for the generation of functional, single-use antibody purification reagents. Straightforward preparation of purification reagents will help make antibody purification from genetically modified crop plants feasible and address one of the major bottlenecks facing commercialization of plant-derived pharmaceuticals.

Bioactive paper provides a low-cost platform for diagnostics

Bioactive paper includes a range of potential paper-based materials that can perform analytical functions normally reserved for multi-well plates in the laboratory or for portable electronic devices. Pathogen detection is the most compelling application. Simple paper-based detection, not requiring hardware, has the potential to have impacts in society, ranging from the kitchen to disasters in the developing world. Bioactive-paper research is an emerging field with significant efforts in Canada, USA (Harvard), Finland and Australia. Following a brief introduction to the material and surface properties of paper, I review the literature. Some of the early work exploits the porosity of paper to generate paper-based microfluidics ("paperfluidics") devices. I exclude from this review printed electronic devices and plastics-supported devices.