Human anti-gold antibodies: biofunctionalization of gold nanoparticles and surfaces with anti-gold antibodies

Nanoparticle-induced immune response: Health risk versus treatment opportunity?

Nanoparticles (NPs) are not only employed in many biomedical applications in an engineered form, but also occur in our environment, in a more hazardous form. NPs interact with the immune system through various pathways and can lead to a myriad of different scenarios, ranging from their quiet removal from circulation by macrophages without any impact for the body, to systemic inflammatory effects and immuno-toxicity. In the latter case, the function of the immune system is affected by the presence of NPs. This review describes, how both the innate and adaptive immune system are involved in interactions with NPs, together with the models used to analyse these interactions. These models vary between simple 2D in vitro models, to in vivo animal models, and also include complex all human organ on chip models which are able to recapitulate more accurately the interaction in the in vivo situation. Thereafter, commonly encountered NPs in both the environment and in biomedical applications and their possible effects on the immune system are discussed in more detail. Not all effects of NPs on the immune system are detrimental; in the final section, we review several promising strategies in which the immune response towards NPs can be exploited to suit specific applications such as vaccination and cancer immunotherapy.

A Nanomedicine Structure-Activity Framework for Research, Development, and Regulation of Future Cancer Therapies

Despite their clinical success in drug delivery applications, the potential of theranostic nanomedicines is hampered by mechanistic uncertainty and a lack of science-informed regulatory guidance. Both the therapeutic efficacy and the toxicity of nanoformulations are tightly controlled by the complex interplay of the nanoparticle's physicochemical properties and the individual patient/tumor biology; however, it can be difficult to correlate such information with observed outcomes. Additionally, as nanomedicine research attempts to gradually move away from large-scale animal testing, the need for computer-assisted solutions for evaluation will increase. Such models will depend on a clear understanding of structure-activity relationships. This review provides a comprehensive overview of the field of cancer nanomedicine and provides a knowledge framework and foundational interaction maps that can facilitate future research, assessments, and regulation. By forming three complementary maps profiling nanobio interactions and pathways at different levels of biological complexity, a clear picture of a nanoparticle's journey through the body and the therapeutic and adverse consequences of each potential interaction are presented.

Phage Display Derived Monoclonal Antibodies: From Bench to Bedside

Monoclonal antibodies (mAbs) have become one of the most important classes of biopharmaceutical products, and they continue to dominate the universe of biopharmaceutical markets in terms of approval and sales. They are the most profitable single product class, where they represent six of the top ten selling drugs. At the beginning of the 1990s, an in vitro antibody selection technology known as antibody phage display was developed by John McCafferty and Sir. Gregory Winter that enabled the discovery of human antibodies for diverse applications, particularly antibody-based drugs. They created combinatorial antibody libraries on filamentous phage to be utilized for generating antigen specific antibodies in a matter of weeks. Since then, more than 70 phage–derived antibodies entered clinical studies and 14 of them have been approved. These antibodies are indicated for cancer, and non-cancer medical conditions, such as inflammatory, optical, infectious, or immunological diseases. This review will illustrate the utility of phage display as a powerful platform for therapeutic antibodies discovery and describe in detail all the approved mAbs derived from phage display.

Phage Display Derived Monoclonal Antibodies: From Bench to Bedside

Monoclonal antibodies (mAbs) have become one of the most important classes of biopharmaceutical products, and they continue to dominate the universe of biopharmaceutical markets in terms of approval and sales. They are the most profitable single product class, where they represent six of the top ten selling drugs. At the beginning of the 1990s, an in vitro antibody selection technology known as antibody phage display was developed by John McCafferty and Sir. Gregory Winter that enabled the discovery of human antibodies for diverse applications, particularly antibody-based drugs. They created combinatorial antibody libraries on filamentous phage to be utilized for generating antigen specific antibodies in a matter of weeks. Since then, more than 70 phage-derived antibodies entered clinical studies and 14 of them have been approved. These antibodies are indicated for cancer, and non-cancer medical conditions, such as inflammatory, optical, infectious, or immunological diseases. This review will illustrate the utility of phage display as a powerful platform for therapeutic antibodies discovery and describe in detail all the approved mAbs derived from phage display.

Complementary Design for Pairing between Two Types of Nanoparticles Mediated by a Bispecific Antibody: Bottom-Up Formation of Porous Materials from Nanoparticles

Recent advances in biotechnology have enabled the generation of antibodies with high affinity for the surfaces of specific inorganic materials. Herein, we report the synthesis of functional materials from multiple nanomaterials by using a small bispecific antibody recombinantly constructed from gold-binding and ZnO-binding antibody fragments. The bispecific antibody-mediated spontaneous linkage of gold and ZnO nanoparticles forms a binary gold-ZnO nanoparticle composite membrane. The relatively low melting point of the gold nanoparticles and the solubility of ZnO in dilute acidic solution then allowed for the bottom-up synthesis of a nanoporous gold membrane by means of a low-energy, low-environmental-load protocol. The nanoporous gold membrane showed high catalytic activity for the reduction of p-nitrophenol to p-aminophenol by sodium borohydride. Here, we show the potential utility of nanoparticle pairing mediated by bispecific antibodies for the bottom-up construction of nanostructured materials from multiple nanomaterials.

Hide and Seek: Nanomaterial Interactions With the Immune System

Engineered nanomaterials hold promise for a wide range of applications in medicine. However, safe use of nanomaterials requires that interactions with biological systems, not least with the immune system, are understood. Do nanomaterials elicit novel or unexpected effects, or is it possible to predict immune responses to nanomaterials based on how the immune system handles pathogens? How does the bio-corona of adsorbed biomolecules influence subsequent immune interactions of nanomaterials? How does the grafting of polymers such as poly(ethylene glycol) onto nanomaterial surfaces impact on these interactions? Can ancient immune evasion or “stealth” strategies of pathogens inform the design of nanomaterials for biomedical applications? Can nanoparticles co-opt immune cells to target diseased tissues? The answers to these questions may prove useful for the development of nanomedicines.

Therapeutic targeting in nanomedicine: the future lies in recombinant antibodies

The unique chemical and functional properties of nanoparticles can be harnessed for the delivery of large quantities of various therapeutic biomolecules. Active targeting of nanoparticles by conjugating ligands that bind to target cells strongly facilitates accumulation, internalization into target cells and longer retention at the target site, with consequent enhanced therapeutic effects. Recombinant antibodies with high selectivity and availability for a vast range of targets will dominate the future. In this review, we systematically outline the tremendous progress in the conjugation of antibodies to nanoparticles and the clear advantages that recombinant antibodies offer in the therapeutic targeting of nanoparticles. The demonstrated flexibility of recombinant antibody coupling to nanoparticles highlights the bright future of this technology for modern therapeutic nanomedicine.

Understanding the immunogenicity and antigenicity of nanomaterials: Past, present and future

Nanoparticle immunogenicity and antigenicity have been under investigation for many years. During the past decade, significant progress has been made in understanding what makes a nanoparticle immunogenic, how immune cells respond to nanoparticles, what consequences of nanoparticle-specific antibody formation exist and how they challenge the application of nanoparticles for drug delivery. Moreover, it has been recognized that accidental contamination of therapeutic protein formulations with nanosized particulate materials may contribute to the immunogenicity of this type of biotechnology products. While the immunological properties of engineered nanomaterials and their application as vaccine carriers and adjuvants have been given substantial consideration in the current literature, little attention has been paid to nanoparticle immuno- and antigenicity. To fill in this gap, we herein provide an overview of this subject to highlight the current state of the field, review past and present research, and discuss future research directions.

Development and characterization of antibody reagents for detecting nanoparticles

The increasing use of nanoparticles (NPs) in technological applications and in commercial products has escalated environmental health and safety concerns. The detection of NPs in the environment and in biological systems is challenged by limitations associated with commonly used analytical techniques. In this paper we report on the development and characterization of NP binding antibodies, termed NProbes. Phage display methodology was used to discover antibodies that bind NPs dispersed in solution. We present a proof-of-concept for the generation of NProbes and their use for detecting quantum dots and titanium dioxide NPs in vitro and in an ex vivo human skin model. Continued development and refinement of NProbes to detect NPs that vary in composition, shape, size, and surface coating will comprise a powerful tool kit that can be used to advance nanotechnology research particularly in the nanotoxicology and nanotherapeutics fields.

Solid-binding peptides: smart tools for nanobiotechnology

Over the past decade, solid-binding peptides (SBPs) have been used increasingly as molecular building blocks in nanobiotechnology. These peptides show selectivity and bind with high affinity to the surfaces of a diverse range of solid materials including metals, metal oxides, metal compounds, magnetic materials, semiconductors, carbon materials, polymers, and minerals. They can direct the assembly and functionalisation of materials, and have the ability to mediate the synthesis and construction of nanoparticles and complex nanostructures. As the availability of newly synthesised nanomaterials expands rapidly, so too do the potential applications for SBPs.

Immunosuppressive and anti-inflammatory properties of engineered nanomaterials

Nanoparticle interactions with various components of the immune system are determined by their physicochemical properties such as size, charge, hydrophobicity and shape. Nanoparticles can be engineered to either specifically target the immune system or to avoid immune recognition. Nevertheless, identifying their unintended impacts on the immune system and understanding the mechanisms of such accidental effects are essential for establishing a nanoparticle's safety profile. While immunostimulatory properties have been reviewed before, little attention in the literature has been given to immunosuppressive and anti-inflammatory properties. The purpose of this review is to fill this gap. We will discuss intended immunosuppression achieved by either nanoparticle engineering, or the use of nanoparticles to carry immunosuppressive or anti-inflammatory drugs. We will also review unintended immunosuppressive properties of nanoparticles per se and consider how such properties could be either beneficial or adverse.

Design and applications of bispecific heterodimers: molecular imaging and beyond

Ligand-based molecular imaging probes have been designed with high affinity and specificity for monitoring biological process and responses. Single-target recognition by traditional probes can limit their applicability for disease detection and therapy because synergistic action between disease mediators and different receptors is often involved in disease progression. Consequently, probes that can recognize multiple targets should demonstrate higher targeting efficacy and specificity than their monospecific peers. This concept has been validated by multiple bispecific heterodimer-based imaging probes that have demonstrated promising results in several animal models. This review summarizes the design strategies for bispecific peptide- and antibody-based heterodimers and their applications in molecular targeting and imaging. The design and application of bispecific heterodimer-conjugated nanomaterials are also discussed.

General in vitro method to analyze the interactions of synthetic polymers with human antibody repertoires

Recent reports on the hitherto underestimated antigenicity of poly(ethylene glycol) (PEG), which is widely used for pharmaceutical applications, highlight the need for efficient testing of polymer antigenicity and for a better understanding of its molecular origins. With this goal in mind, we have used the phage-display technique to screen large, recombinant antibody repertoires of human origin in vitro for antibodies that bind poly(vinylpyrrolidone) (PVP). PVP is a neutral synthetic polymer of industrial and clinical interest that is also a well-known model antigen in animal studies, thus allowing the comparison of in vitro and in vivo responses. We have identified 44 distinct antibodies that bind specifically to PVP. Competitive binding assays show that the PVP-antibody binding constant is proportional to the polymerization degree of PVP and that specific binding is detected down to the vinylpyrrolidone (VP) monomer level. Statistical analysis of anti-PVP antibody sequences identifies an amino-acid motif that is shared by many phage-display-selected anti-PVP antibodies that are similar to a previously described natural anti-PVP antibody. This suggests a role for this motif in specific antibody/PVP interactions. Interestingly, sequence analysis also suggests that only a single antibody chain containing this shared motif is responsible for antibody binding to PVP, as confirmed upon systematic deletion of either antibody chain for 90% of selected anti-PVP antibodies. Overall, a large number of antibodies in the human repertoires we have screened bind specifically to PVP through a small number of shared amino acid motifs, and preliminary comparison points to significant correlations between the sequences of phage-display-selected anti-PVP antibodies and their natural counterparts isolated from immunized mice in previous studies. This study pioneers the use of antibody phage-display to explore the antigenicity of biotechnologically relevant polymers. It also paves the way for a fast, cost-effective, and systematic in vitro analysis, thus reducing the need for animal immunization experiments. Moreover, identifying the encoding DNA sequence of polymer-binding antibodies via phage-display enables future applications of a molecular biology approach to protein-polymer conjugation, based on protein-antibody fusion.

Application of 300× enhanced fluorescence on a plasmonic chip modified with a bispecific antibody to a sensitive immunosensor

The grating substrate covered with a metal layer, a plasmonic chip, and a bispecific antibody can play a key role in the sensitive detection of a marker protein with an immunosensor, because of the provision of an enhanced fluorescence signal and the preparation of a sensor surface densely modified with capture antibody, respectively. In this study, one of the tumor markers, a soluble epidermal growth factor receptor (sEGFR), was selected as the target to be detected. The ZnO- and silver-coated plasmonic chip with precise regularity and the appropriate duty ratio in the periodic structure further enhanced the fluorescence intensity. As for sensor surface modification with capture antibody, a bispecific antibody (anti-sEGFR and anti-ZnO antibody), the concentrated bispecific antibody solution was found to nonlinearly form a surface densely immobilized with antibody, because the binding process of a bispecific antibody to the ZnO surface can be a competitive process with adsorption of phosphate. As a result, the interface on the plasmonic chip provided a 300× enhanced fluorescence signal compared with that on a ZnO-coated glass slide, and therefore sEGFR was found to be quantitatively detected in a wide concentration range from 10 nM to 700 fM on our plasmonic surface.

A high-affinity gold-binding camel antibody: antibody engineering for one-pot functionalization of gold nanoparticles as biointerface molecules

Antibodies, with their high affinity and specificity, are widely utilized in the field of protein engineering, medicinal chemistry, and nanotechnology applications, and our recent studies have demonstrated the recognition and binding of antibody for the surface on inorganic material. In this study, we generated a high-affinity gold-binding antibody fragment by a combination of peptide-grafting and phage-display techniques and showed the availability of the material-binding fragment for one-pot functionalization of nanoparticles as interface molecules. After a gold-binding peptide sequence was grafted into one of the complementarity determining regions of a single variable domain of a heavy-chain camel antibody, a combinatorial library approach raised by 20 times the affinity of the peptide-grafted fragment. The high-affinity gold-binding fragment (E32) spontaneously adsorbed on gold nanoparticles, and consequently the nanoparticles formed a stable dispersion in a high-ionic-strength solution. Multivalent and bispecific antibodies constructed on the E32 platform by means of fusion technology functionalized gold nanoparticles in one pot, and these functionalized nanoparticles could be used to obtain surface plasmon resonance scattering images of cancer cells and to spontaneously link two different nanomaterials. Here, we propose the bispecific antibodies as convenient interface molecules in the nanosized world.

Biomimetic engineering of modular bispecific antibodies for biomolecule immobilization

Modular bispecific antibodies (BsAb's) that interact directly with a gold surface were engineered for immobilization on biosensing devices. The BsAb's consist of the variable fragments of antigold and antilysozyme antibodies connected via one of three linkers derived from naturally occurring proteins. The BsAb's were bound tightly to both the gold surface and to lysozyme, thus functioning as interface molecules between lysozyme and the gold surface without a substantial loss of antigen-binding activity. The antigen-binding capacity (the ratio of the amount of immobilized lysozyme to the amount of immobilized BsAb) on the gold surface reached 82%. An analysis of the correlation between binding capacity and linker characteristics indicated that the presence of a long, rigid linker sequence derived from a cellulase resulted in a higher antigen-binding capacity than did the presence of a long but relatively flexible glycine-rich linker. This result suggests a strategy for designing linkers suitable for BsAb-based biomolecular immobilization.

Enhancement of cellulolytic enzyme activity by clustering cellulose binding domains on nanoscaffolds

Cellulose, one of the most abundant carbon resources, is degraded by cellulolytic enzymes called cellulases. Cellulases are generally modular proteins with independent catalytic and cellulose-binding domain (CBD) modules and, in some bacteria, catalytic modules are noncovalently assembled on a scaffold protein with CBD to form a giant protein complex called a cellulosome, which efficiently degrades water-insoluble hard materials. In this study, a catalytic module and CBD are independently prepared by recombinant means, and are heterogeneously clustered on streptavidin and on inorganic nanoparticles for the construction of artificial cellulosomes. Heteroclustering of the catalytic module with CBD results in significant improvements in the enzyme's degradation activity for water-insoluble substrates. In particular, the increase of CBD valency in the cluster structure critically enhances the catalytic activity by improving the affinity for substrates, and clustering with multiple CBDs on CdSe nanoparticles generates a 7.2-fold increase in the production of reducing sugars relative to that of the native free enzyme. The multivalent design of substrate-binding domain on clustered cellulases is important for the construction of the artificial cellulosome, and the nanoparticles are an effective scaffold for increasing the valence of CBD in clustered cellulases. A new design is proposed for artificial cellulosomes with multiple CBDs on noncellulosome-derived scaffold structures.

Beyond natural antibodies: the power of in vitro display technologies

In vitro display technologies, best exemplified by phage and yeast display, were first described for the selection of antibodies some 20 years ago. Since then, many antibodies have been selected and improved upon using these methods. Although it is not widely recognized, many of the antibodies derived using in vitro display methods have properties that would be extremely difficult, if not impossible, to obtain by immunizing animals. The first antibodies derived using in vitro display methods are now in the clinic, with many more waiting in the wings. Unlike immunization, in vitro display permits the use of defined selection conditions and provides immediate availability of the sequence encoding the antibody. The amenability of in vitro display to high-throughput applications broadens the prospects for their wider use in basic and applied research.

Superparamagnetic iron oxide nanotheranostics for targeted cancer cell imaging and pH-dependent intracellular drug release

Studies were conducted to develop antibody- and fluorescence-labeled superparamagnetic iron oxide nanoparticle (SPIO) nanotheranostics for magnetic resonance imaging (MRI) and fluorescence imaging of cancer cells and pH-dependent intracellular drug release. SPIO nanoparticles (10 nm) were coated with amphiphilic polymers and PEGylated. The antibody HuCC49ΔCH2 and fluorescent dye 5-FAM were conjugated to the PEG of iron oxide nanoparticles (IONPs). Anticancer drugs doxorubicin (Dox), azido-doxorubicin (Adox), MI-219, and 17-DMAG containing primary amine, azide, secondary amine, and tertiary amine, respectively, were encapsulated into IONPs. The encapsulation efficiency and drug release at various pHs were determined using LC-MS/MS. The cancer targeting and imaging were monitored using MRI and fluorescent microscopy in a colon cancer cell line (LS174T). The pH-dependent drug release, intracellular distribution, and cytotoxicity were evaluated using microscopy and MTS assay. The PEGylation of SPIO and conjugation with antibody and 5-FAM increased SPIO size from 18 to 44 nm. Fluorescent imaging, magnetic resonance imaging (MRI) and Prussian blue staining demonstrated that HuCC49ΔCH2-SPIO increased cancer cell targeting. HuCC49ΔCH2-SPIO nanotheranostics decreased the T(2) values in MRI of LS174T cells from 117.3 ± 1.8 ms to 55.5 ± 2.6 ms. The loading capacities of Dox, Adox, MI-219, and 17-DMAG were 3.16 ± 0.77%, 6.04 ± 0.61%, 2.22 ± 0.42%, and 0.09 ± 0.07%, respectively. Dox, MI-219 and 17-DMAG showed pH-dependent release while Adox did not. Fluorescent imaging demonstrated the accumulation of HuCC49ΔCH2-SPIO nanotheranostics in endosomes/lysosomes. The encapsulated Dox was released in acidic lysosomes and diffused into cytosol and nuclei. In contrast, the encapsulated Adox only showed limited release in endosomes/lysosomes. HuCC49ΔCH2-SPIO nanotheranostics target-delivered more Dox to LS174T cells than nonspecific IgG-SPIO and resulted in a lower IC(50) (1.44 μM vs 0.44 μM). The developed HuCC49ΔCH2-SPIO nanotheranostics provides an integrated platform for cancer cell imaging, targeted anticancer drug delivery and pH-dependently drug release.

Direct immobilization of gold-binding antibody fragments for immunosensor applications

A novel method that enables antibody fragments to be immobilized on a sensor substrate with a high binding capability using molecular recognition has been developed. Using genetic engineering, we fabricated bispecific recombinant antibody fragments, which consist of two kinds of antibody fragments: a gold antibody fragment and a target molecule antibody fragment. Surface plasmon resonance (SPR) analysis indicated that these gold-binding bispecific antibody fragments bind directly to the gold substrate with high affinity (K(D) approximately 10(-9) M). About 70% of the bispecific antibody fragments immobilized on the gold substrate retained their target protein-binding efficiency. The Sips isotherm was used to assess the heterogeneity in antibody affinity for the bispecific antibody fragments. The results showed that the immobilized bispecific antibody fragments exhibited an increased homogeneity of affinity (K(D)) to target molecules when compared with monospecific antibody fragments immobilized by conventional methods. The use of bispecific antibody fragments to directly immobilize antibody fragments on a solid-phase substrate offers a useful platform for immunosensor applications.

Protein-protein interactions and selection: generation of molecule-binding proteins on the basis of tertiary structural information

Antibodies and their fragments are attractive binding proteins because their high binding strength is generated by several hypervariable loop regions, and because high-quality libraries can be prepared from the vast gene clusters expressed by mammalian lymphocytes. Recent explorations of new genome sequences and protein structures have revealed various small, nonantibody scaffold proteins. Accurate structural descriptions of protein-protein interactions based on X-ray and NMR analyses allow us to generate binding proteins by using grafting and library techniques. Here, we review approaches for generating binding proteins from small scaffold proteins on the basis of tertiary structural information. Identification of binding sites from visualized tertiary structures supports the transfer of function by peptide grafting. The local library approach is advantageous as a go-between technique for grafted foreign peptide sequences and small scaffold proteins. The identification of binding sites also supports the construction of efficient libraries with a low probability of denatured variants, and, in combination with the design for library diversity, opens the way to increasing library density and randomized sequence lengths without decreasing density. Detailed tertiary structural analyses of protein-protein complexes allow accurate description of epitope locations to enable the design of and screening for multispecific, high-affinity proteins recognizing multiple epitopes in target molecules.

High affinity anti-inorganic material antibody generation by integrating graft and evolution technologies: potential of antibodies as biointerface molecules

Recent advances in molecular evolution technology enabled us to identify peptides and antibodies with affinity for inorganic materials. In the field of nanotechnology, the use of the functional peptides and antibodies should aid the construction of interface molecules designed to spontaneously link different nanomaterials; however, few material-binding antibodies, which have much higher affinity than short peptides, have been identified. Here, we generated high affinity antibodies from material-binding peptides by integrating peptide-grafting and phage-display techniques. A material-binding peptide sequence was first grafted into an appropriate loop of the complementarity determining region (CDR) of a camel-type single variable antibody fragment to create a low affinity material-binding antibody. Application of a combinatorial library approach to another CDR loop in the low affinity antibody then clearly and steadily promoted affinity for a specific material surface. Thermodynamic analysis demonstrated that the enthalpy synergistic effect from grafted and selected CDR loops drastically increased the affinity for material surface, indicating the potential of antibody scaffold for creating high affinity small interface units. We show the availability of the construction of antibodies by integrating graft and evolution technology for various inorganic materials and the potential of high affinity material-binding antibodies in biointerface applications.