Nathan J Alves | Indiana University (original) (raw)

Papers by Nathan J Alves

Journal of Controlled Release, Dec 1, 2014

Carfilzomib, a recently FDA-approved proteasome inhibitor, has remarkable anti-myeloma (MM) activ... more Carfilzomib, a recently FDA-approved proteasome inhibitor, has remarkable anti-myeloma (MM) activity. However, its effectiveness is limited by associated severe side-effects, short circulation half-life, and limited solubility. Here, we report the engineering of liposomal carfilzomib nanoparticles to overcome these problems and enhance the therapeutic efficacy of carfilzomib by increasing tumoral drug accumulation while decreasing systemic toxicity. In our design, carfilzomib was loaded into the bilayer of liposomes to yield stable and reproducible liposomal nanoparticles. Liposomal carfilzomib nanoparticles were efficiently taken up by MM cells, demonstrated proteasome inhibition, induced apoptosis, and exhibited enhanced cytotoxicity against MM cells. In vivo, liposomal carfilzomib demonstrated significant tumor growth inhibition and dramatically reduced overall systemic toxicity compared to free carfilzomib. Finally, liposomal carfilzomib demonstrated enhanced synergy in combination with doxorubicin. Taken together, this study establishes the successful synthesis of liposomal carfilzomib nanoparticles that demonstrates improved therapeutic index and the potential to improve patient outcome in MM.

Thrombosis Research, Mar 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Proceedings of IMPRS, Dec 10, 2021

Journal of Visualized Experiments, Nov 16, 2016

An increasing interest in applying synthetic biology techniques to program outer membrane vesicle... more An increasing interest in applying synthetic biology techniques to program outer membrane vesicles (OMV) are leading to some very interesting and unique applications for OMV where traditional nanoparticles are proving too difficult to synthesize. To date, all Gram-negative bacteria have been shown to produce OMV demonstrating packaging of a variety of cargo that includes small molecules, peptides, proteins and genetic material. Based on their diverse cargo, OMV are implicated in many biological processes ranging from cell-cell communication to gene transfer and delivery of virulence factors depending upon which bacteria are producing the OMV. Only recently have bacterial OMV become accessible for use across a wide range of applications through the development of techniques to control and direct packaging of recombinant proteins into OMV. This protocol describes a method for the production, purification, and use of enzyme packaged OMV providing for improved overall production of recombinant enzyme, increased vesiculation, and enhanced enzyme stability. Successful utilization of this protocol will result in the creation of a bacterial strain that simultaneously produces a recombinant protein and directs it for OMV encapsulation through creating a synthetic linkage between the recombinant protein and an outer membrane anchor protein. This protocol also details methods for isolating OMV from bacterial cultures as well as proper handling techniques and things to consider when adapting this protocol for use for other unique applications such as: pharmaceutical drug delivery, medical diagnostics, and environmental remediation.

Expert Opinion on Drug Delivery, Jan 25, 2016

The targeted delivery of therapeutic agents greatly increases their effectiveness while simultane... more The targeted delivery of therapeutic agents greatly increases their effectiveness while simultaneously reducing negative side effects. In the past, targeting of therapeutics has been accomplished with nucleic acids, peptides/proteins, and conventional antibodies. A promising alternative to the conventional antibodies often used in therapeutic targeting are significantly smaller-sized antibody fragments known as single-domain antibodies (sdAbs). Areas Covered: Recent advances in the utility of sdAbs for targeting of therapeutic agents along with relevant examples from the literature are discussed. Their advantages when compared to other targeting strategies as well as their challenges and limitations is also covered. Expert Opinion: The development of sdAb-based targeted therapeutics will likely continue. The identification of novel protein modification techniques will provide more options for sdAb modification (conjugation, immobilization, functionalization), allowing a wider array of therapeutic agents to be successfully targeted and delivered using sdAbs. This will also spur the selection of sdAbs with specificity for other targets having relevance towards therapeutics.

Journal of Physical Chemistry Letters, Feb 15, 2012

This study describes a strategy where antibody selectivity for high antigen-density surfaces is e... more This study describes a strategy where antibody selectivity for high antigen-density surfaces is enhanced by forming a thermodynamically stable bicyclic complex. The bicyclic complex was formed via multivalent interactions of the antibody with a synthetic trivalent mimotope at a 3:2 molar ratio. Complex formation was analyzed using dynamic light scattering and analytical ultracentrifugation, showing a hydrodynamic radius of ∼22 nm and a calculated molecular weight of 397 kDa, depicting a trimeric complex formation. The complex has high thermodynamic stability and results in a 10fold higher binding affinity for the trivalent mimotope (K d = 0.14 μM) compared to the monovalent mimotope (K d = 1.4 μM). As bicyclic complexes, the antibodies showed ∼18% binding of the monomeric form to low antigen-density surfaces. At high antigen-density, antibody binding was equal whether delivered as a complex or a monomer. These results establish bicyclic complex selectivity for high antigen-density surfaces and suggest a potential method to enhance therapeutic antibody selectivity for diseased cells. SECTION: Biophysical Chemistry

Therapeutic Delivery, Jul 1, 2015

Nanoparticle-based therapeutics are poised to play a critical role in treating disease. These com... more Nanoparticle-based therapeutics are poised to play a critical role in treating disease. These complex multifunctional drug delivery vehicles provide for the passive and active targeted delivery of numerous small molecule, peptide and protein-derived pharmaceuticals. This article will first discuss some of the current state of the art nanoparticle classes (dendrimers, lipid-based, polymeric and inorganic), highlighting benefits/drawbacks associated with their implementation. We will then discuss an emerging class of nanoparticle therapeutics, bacterial outer membrane vesicles, that can provide many of the nanoparticle benefits while simplifying assembly. Through molecular biology techniques; outer membrane vesicle hijacking potentially allows for stringent control over nanoparticle production allowing for targeted protein packaged nanoparticles to be fully synthesized by bacteria.

ACS Applied Materials & Interfaces, Oct 29, 2015

All bacteria shed outer membrane vesicles (OMVs) loaded with a diverse array of small molecules, ... more All bacteria shed outer membrane vesicles (OMVs) loaded with a diverse array of small molecules, proteins, and genetic cargo. In this study we sought to hijack the bacterial cell export pathway to simultaneously produce, package, and release an active enzyme, phosphotriesterase (PTE). To accomplish this goal the SpyCatcher/SpyTag (SC/ST) bioconjugation system was utilized to produce a PTE-SpyCatcher (PTE-SC) fusion protein and a SpyTagged transmembrane porin protein (OmpA-ST), known to be abundant in OMVs. Under a range of physiological conditions the SpyTag and SpyCatcher domains interact with one another and form a covalent isopeptide bond driving packaging of PTE into forming OMVs. The PTE-SC loaded OMVs are characterized for size distribution, number of vesicles produced, cell viability, packaged PTE enzyme kinetics, OMV loading efficiency, and enzyme stability following iterative cycles of freezing and thawing. The PTE-loaded OMVs exhibit native-like enzyme kinetics when assayed with paraoxon as a substrate. PTE is often toxic to expression cultures and has a tendency to lose activity with improper handling. The coexpression of OmpA-ST with PTE-SC, however, greatly improved the overall PTE production levels by mitigating toxicity through exporting of the PTE-SC and greatly enhanced packaged enzyme stability against iterative cycles of freezing and thawing.

In the continuing search for effective treatments for cancer, here we report the rational enginee... more In the continuing search for effective treatments for cancer, here we report the rational engineering of a novel multifunctional nanoparticle that combines traditional chemotherapy with cell targeting and anti-cellular-adhesion functionalities to selectively target multiple myeloma (MM) cells and overcome cell adhesion-mediated drug resistance (CAM-DR). Anti-cellular-adhesion evolves as a promising target in oncology. VLA-4-mediated adhesion to the bone marrow extracellular matrix and stromal cells confers MM cells with CAM-DR. In our design, we used micellar nanoparticles as dynamic self-assembling scaffolds to present VLA-4-antagonist peptides and doxorubicin conjugates simultaneously to selectively target MM cells and to overcome CAM-DR. Doxorubicin was conjugated to the nanoparticles through an pH-sensitive hydrazone bond to prevent premature release and thus non-specific toxicity. Peptides were conjugated via a multifaceted synthetic procedure for generating precisely controlled number of targeting functionalities per nanoparticle. The nanoparticles, which exhibited a size of ∼20nm, were efficiently internalized by MM cells with an optimal peptide valency of 20 per micelle, and induced cytotoxicity to MM cells. Mechanistic studies revealed that nanoparticles induced DNA double strand breaks as evidenced by H2AX phosphorylation, and triggered apoptosis, which was associated with PARP and caspase-8 cleavage. Importantly, multifunctional nanoparticles were more efficacious than doxorubicin in the presence of fibronectin (IC50=0.15±0.04 μM and 0.42±0.09 μM, respectively), and overcame CAM-DR induced by adherence of MM cells to fibronectin. Finally, in a MM xenograft model, nanoparticles preferentially homed to MM tumors, with a ∼10 fold more drug accumulation when compared to doxorubicin, and demonstrated dramatic tumor growth inhibition with much reduced overall systemic toxicity. Taken together, we demonstrate the disease-driven engineering of a nanoparticle-based drug delivery system, enabling the model of an integrative approach in the treatment of MM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5686. doi:1538-7445.AM2012-5686

Scientific Reports, Apr 27, 2016

Bacteria possess innate machinery to transport extracellular cargo between cells as well as packa... more Bacteria possess innate machinery to transport extracellular cargo between cells as well as package virulence factors to infect host cells by secreting outer membrane vesicles (OMVs) that contain small molecules, proteins, and genetic material. These robust proteoliposomes have evolved naturally to be resistant to degradation and provide a supportive environment to extend the activity of encapsulated cargo. In this study, we sought to exploit bacterial OMV formation to package and maintain the activity of an enzyme, phosphotriesterase (PTE), under challenging storage conditions encountered for real world applications. Here we show that OMV packaged PTE maintains activity over free PTE when subjected to elevated temperatures (>100-fold more activity after 14 days at 37 °C), iterative freeze-thaw cycles (3.4-fold post four-cycles), and lyophilization (43-fold). We also demonstrate how lyophilized OMV packaged PTE can be utilized as a cell free reagent for long term environmental remediation of pesticide/chemical warfare contaminated areas.

Blood Cancer Journal, Apr 1, 2012

In the continuing search for effective cancer treatments, we report the rational engineering of a... more In the continuing search for effective cancer treatments, we report the rational engineering of a multifunctional nanoparticle that combines traditional chemotherapy with cell targeting and anti-adhesion functionalities. Very late antigen-4 (VLA-4) mediated adhesion of multiple myeloma (MM) cells to bone marrow stroma confers MM cells with cell-adhesion-mediated drug resistance (CAM-DR). In our design, we used micellar nanoparticles as dynamic self-assembling scaffolds to present VLA-4-antagonist peptides and doxorubicin (Dox) conjugates, simultaneously, to selectively target MM cells and to overcome CAM-DR. Dox was conjugated to the nanoparticles through an acid-sensitive hydrazone bond. VLA-4-antagonist peptides were conjugated via a multifaceted synthetic procedure for generating precisely controlled number of targeting functionalities. The nanoparticles were efficiently internalized by MM cells and induced cytotoxicity. Mechanistic studies revealed that nanoparticles induced DNA double-strand breaks and apoptosis in MM cells. Importantly, multifunctional nanoparticles overcame CAM-DR, and were more efficacious than Dox when MM cells were cultured on fibronectin-coated plates. Finally, in a MM xenograft model, nanoparticles preferentially homed to MM tumors with B10 fold more drug accumulation and demonstrated dramatic tumor growth inhibition with a reduced overall systemic toxicity. Altogether, we demonstrate the disease driven engineering of a nanoparticle-based drug delivery system, enabling the model of an integrative approach in the treatment of MM.

Journal of Visualized Experiments, Nov 16, 2016

Biomaterials, Jul 1, 2013

The conserved nucleotide binding site (NBS), found in the Fab variable domain of all antibody iso... more The conserved nucleotide binding site (NBS), found in the Fab variable domain of all antibody isotypes, remains a not-so-widely known and under-utilized site. Here, we describe a UV photocrosslinking method (UV-NBS) that utilizes the NBS for site-specific covalent functionalization of antibodies, while preserving antibody activity. We identified a small molecule, indole-3-butyric acid (IBA), which has affinity for the NBS (K d ¼ 1e8 mM) and can be photocrosslinked to antibodies upon UV energy exposure. By synthesizing their IBA conjugated versions, we have successfully photocrosslinked various types of functional ligands to antibodies at the NBS, including affinity tags (biotin), fluorescent molecules (FITC), peptides (iRGD), and chemotherapeutics (paclitaxel). An optimal UV exposure of 1e2 J/cm 2 yielded the most efficient photocrosslinking and resulted in 1e2 conjugations per antibody, while preserving the antigen binding activity and Fc related functions. Analysis of the photocrosslinked conjugates using western blotting, mass spectrometry, and computational docking simulations demonstrated that the photocrosslinking specifically takes place at the Y/F42 residue in framework region 2 of the antibody light chain. Taken together, the UV-NBS method provides a practical, site-specific, and chemically efficient method to functionalize antibodies with significant implications in diagnostic and therapeutic settings.

Analytical Chemistry, Sep 7, 2012

The conserved nucleotide binding site (NBS), found within the Fab variable domain of antibodies, ... more The conserved nucleotide binding site (NBS), found within the Fab variable domain of antibodies, remains a not-so-widely known and underutilized site. Here we describe a novel affinity chromatography method that utilizes the NBS as a target for selectively purifying antibodies from complex mixtures. The affinity column was prepared by coupling indole butyric acid (IBA), which has a monovalent affinity for the NBS with a K d ranging between 1 and 8 μM, to ToyoPearl resin resulting in the NBS targeting affinity column (NBS IBA). The proof-of-concept studies performed using the chimeric pharmaceutical antibody rituximab demonstrated that antibodies were selectively captured and retained on the NBS IBA column and were successfully eluted by applying a mild NaCl gradient at pH 7.0. Furthermore, the NBS IBA column consistently yielded >95% antibody recovery with >98% purity, even when the antibody was purified from complex mixtures such as conditioned cell culture supernatant, hybridoma media, and mouse ascites fluid. The results presented in this study establish the NBS IBA column as a viable small-molecule-based affinity chromatography method for antibody purification with significant implications in industrial antibody production. Potential advantages of the NBS IBA platform are improved antibody batch quality, enhanced column durability, and reduced overall production cost.

The FASEB Journal, May 1, 2021

Des modes de realisation de l'invention concernent des systemes, des procedes et des composit... more Des modes de realisation de l'invention concernent des systemes, des procedes et des compositions pour l'administration d'un medicament a l'aide d'une nanoparticule a des cellules ou tissus cibles. Un systeme d'administration de medicament peut comprendre une nanoparticule ayant un composant de ciblage et un composant therapeutique. La nanoparticule peut avoir un nombre predetermine ou une valence predeterminee de molecules de ciblage pour une interaction multivalente avec une cellule ou un tissu cible. La liaison des molecules de ciblage a la cellule cible peut conduire a la capture a mediation par un recepteur de la nanoparticule par la cellule cible. Le compose therapeutique peut etre administre ulterieurement a l'interieur une vesicule endocytique de la cellule cible. L'invention concerne egalement des systemes d'administration d'un medicament a l'aide de nanoparticules tels que decrits presentement pouvant permettre une efficacite ame...

American Journal of Respiratory Cell and Molecular Biology, Dec 1, 2020

Biosensors and Bioelectronics, Nov 1, 2013

The nucleotide binding site (NBS) is an under-utilized, highly conserved binding site found withi... more The nucleotide binding site (NBS) is an under-utilized, highly conserved binding site found within the variable region of nearly all antibody Fab arms. Here, we describe an NBS specific UV photocrosslinking biotinylation method (UV-NBS Biotin) for the oriented immobilization of antibodies to streptavidin-coated surfaces, such that the antigen binding activity remains unaffected. An optimal UV exposure of 1 J/cm 2 yielded an average conjugation efficiency of ∼1 biotin per antibody resulting in significant immobilization efficiency while maintaining maximal antigen binding activity. With the continued push for miniaturization of medical diagnostics to reduce cost and increase patient accessibility the ever shrinking on chip detection areas necessitate the highest level of immobilized antibody activity to maximize assay detection capabilities. The UV-NBS Biotin method yielded surfaces with significantly enhanced antigen detection capabilities, improved antigen detection sensitivity and the highest amount of active surface immobilized antibody when compared to other common immobilization methods including: ε-NH 3 + surface conjugation, NHS-Biotin, and direct physical adsorption. Taken together, the UV-NBS Biotin method provides a universal, site-specific immobilization method that is amenable to any available assay detection modality with potential significant implications in the development of miniaturized medical diagnostics and lab on a chip technologies.

Bioconjugate Chemistry, Jun 23, 2014

Described here is a UV photo-cross-linking method that utilizes the NBS (nucleotide binding site)... more Described here is a UV photo-cross-linking method that utilizes the NBS (nucleotide binding site) for site-specific covalent functionalization of antibodies with reactive thiol moieties (UV-NBS(Thiol)), while preserving antibody activity. By synthesizing an indole-3-butyric acid (IBA) conjugated version of cysteine we site-specifically photo-cross-linked a reactive thiol moiety to antibodies at the NBS. This thiol moiety can then be used as an orthogonally reactive location to conjugate various types of functional ligands that possess a thiol reactive group through disulfide bond formation or reaction with a maleimide functionalized ligand. Our results demonstrate the utility of the UV-NBS(Thiol) method by successfully functionalizing a prostate specific antigen antibody (IgG(PSA)) with IBA-Thiol and subsequent reaction with maleimide-fluorescein. An optimal UV energy of 0.5-1.5 J/cm(2) was determined to yield the most efficient photo-cross-linking and resulted in 1-1.5 conjugations per antibody while preserving antibody/antigen binding activity and Fc recognition. Utilizing the IBA-Thiol ligand allows for an efficient means of site-specifically conjugating UV sensitive functionalities to antibody NBS that would otherwise not have been amenable by the previously described UV-NBS photo-cross-linking method. The UV-NBS(Thiol) conjugation strategy can be utilized in various diagnostic and therapeutic applications with nearly limitless potential for the preparation of site-specific covalent conjugation of affinity tags, fluorescent molecules, peptides, and chemotherapeutics to antibodies.

Journal of Controlled Release, Dec 1, 2014

Carfilzomib, a recently FDA-approved proteasome inhibitor, has remarkable anti-myeloma (MM) activ... more Carfilzomib, a recently FDA-approved proteasome inhibitor, has remarkable anti-myeloma (MM) activity. However, its effectiveness is limited by associated severe side-effects, short circulation half-life, and limited solubility. Here, we report the engineering of liposomal carfilzomib nanoparticles to overcome these problems and enhance the therapeutic efficacy of carfilzomib by increasing tumoral drug accumulation while decreasing systemic toxicity. In our design, carfilzomib was loaded into the bilayer of liposomes to yield stable and reproducible liposomal nanoparticles. Liposomal carfilzomib nanoparticles were efficiently taken up by MM cells, demonstrated proteasome inhibition, induced apoptosis, and exhibited enhanced cytotoxicity against MM cells. In vivo, liposomal carfilzomib demonstrated significant tumor growth inhibition and dramatically reduced overall systemic toxicity compared to free carfilzomib. Finally, liposomal carfilzomib demonstrated enhanced synergy in combination with doxorubicin. Taken together, this study establishes the successful synthesis of liposomal carfilzomib nanoparticles that demonstrates improved therapeutic index and the potential to improve patient outcome in MM.

Thrombosis Research, Mar 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Proceedings of IMPRS, Dec 10, 2021

Journal of Visualized Experiments, Nov 16, 2016

An increasing interest in applying synthetic biology techniques to program outer membrane vesicle... more An increasing interest in applying synthetic biology techniques to program outer membrane vesicles (OMV) are leading to some very interesting and unique applications for OMV where traditional nanoparticles are proving too difficult to synthesize. To date, all Gram-negative bacteria have been shown to produce OMV demonstrating packaging of a variety of cargo that includes small molecules, peptides, proteins and genetic material. Based on their diverse cargo, OMV are implicated in many biological processes ranging from cell-cell communication to gene transfer and delivery of virulence factors depending upon which bacteria are producing the OMV. Only recently have bacterial OMV become accessible for use across a wide range of applications through the development of techniques to control and direct packaging of recombinant proteins into OMV. This protocol describes a method for the production, purification, and use of enzyme packaged OMV providing for improved overall production of recombinant enzyme, increased vesiculation, and enhanced enzyme stability. Successful utilization of this protocol will result in the creation of a bacterial strain that simultaneously produces a recombinant protein and directs it for OMV encapsulation through creating a synthetic linkage between the recombinant protein and an outer membrane anchor protein. This protocol also details methods for isolating OMV from bacterial cultures as well as proper handling techniques and things to consider when adapting this protocol for use for other unique applications such as: pharmaceutical drug delivery, medical diagnostics, and environmental remediation.

Expert Opinion on Drug Delivery, Jan 25, 2016

The targeted delivery of therapeutic agents greatly increases their effectiveness while simultane... more The targeted delivery of therapeutic agents greatly increases their effectiveness while simultaneously reducing negative side effects. In the past, targeting of therapeutics has been accomplished with nucleic acids, peptides/proteins, and conventional antibodies. A promising alternative to the conventional antibodies often used in therapeutic targeting are significantly smaller-sized antibody fragments known as single-domain antibodies (sdAbs). Areas Covered: Recent advances in the utility of sdAbs for targeting of therapeutic agents along with relevant examples from the literature are discussed. Their advantages when compared to other targeting strategies as well as their challenges and limitations is also covered. Expert Opinion: The development of sdAb-based targeted therapeutics will likely continue. The identification of novel protein modification techniques will provide more options for sdAb modification (conjugation, immobilization, functionalization), allowing a wider array of therapeutic agents to be successfully targeted and delivered using sdAbs. This will also spur the selection of sdAbs with specificity for other targets having relevance towards therapeutics.

Journal of Physical Chemistry Letters, Feb 15, 2012

This study describes a strategy where antibody selectivity for high antigen-density surfaces is e... more This study describes a strategy where antibody selectivity for high antigen-density surfaces is enhanced by forming a thermodynamically stable bicyclic complex. The bicyclic complex was formed via multivalent interactions of the antibody with a synthetic trivalent mimotope at a 3:2 molar ratio. Complex formation was analyzed using dynamic light scattering and analytical ultracentrifugation, showing a hydrodynamic radius of ∼22 nm and a calculated molecular weight of 397 kDa, depicting a trimeric complex formation. The complex has high thermodynamic stability and results in a 10fold higher binding affinity for the trivalent mimotope (K d = 0.14 μM) compared to the monovalent mimotope (K d = 1.4 μM). As bicyclic complexes, the antibodies showed ∼18% binding of the monomeric form to low antigen-density surfaces. At high antigen-density, antibody binding was equal whether delivered as a complex or a monomer. These results establish bicyclic complex selectivity for high antigen-density surfaces and suggest a potential method to enhance therapeutic antibody selectivity for diseased cells. SECTION: Biophysical Chemistry

Therapeutic Delivery, Jul 1, 2015

Nanoparticle-based therapeutics are poised to play a critical role in treating disease. These com... more Nanoparticle-based therapeutics are poised to play a critical role in treating disease. These complex multifunctional drug delivery vehicles provide for the passive and active targeted delivery of numerous small molecule, peptide and protein-derived pharmaceuticals. This article will first discuss some of the current state of the art nanoparticle classes (dendrimers, lipid-based, polymeric and inorganic), highlighting benefits/drawbacks associated with their implementation. We will then discuss an emerging class of nanoparticle therapeutics, bacterial outer membrane vesicles, that can provide many of the nanoparticle benefits while simplifying assembly. Through molecular biology techniques; outer membrane vesicle hijacking potentially allows for stringent control over nanoparticle production allowing for targeted protein packaged nanoparticles to be fully synthesized by bacteria.

ACS Applied Materials & Interfaces, Oct 29, 2015

All bacteria shed outer membrane vesicles (OMVs) loaded with a diverse array of small molecules, ... more All bacteria shed outer membrane vesicles (OMVs) loaded with a diverse array of small molecules, proteins, and genetic cargo. In this study we sought to hijack the bacterial cell export pathway to simultaneously produce, package, and release an active enzyme, phosphotriesterase (PTE). To accomplish this goal the SpyCatcher/SpyTag (SC/ST) bioconjugation system was utilized to produce a PTE-SpyCatcher (PTE-SC) fusion protein and a SpyTagged transmembrane porin protein (OmpA-ST), known to be abundant in OMVs. Under a range of physiological conditions the SpyTag and SpyCatcher domains interact with one another and form a covalent isopeptide bond driving packaging of PTE into forming OMVs. The PTE-SC loaded OMVs are characterized for size distribution, number of vesicles produced, cell viability, packaged PTE enzyme kinetics, OMV loading efficiency, and enzyme stability following iterative cycles of freezing and thawing. The PTE-loaded OMVs exhibit native-like enzyme kinetics when assayed with paraoxon as a substrate. PTE is often toxic to expression cultures and has a tendency to lose activity with improper handling. The coexpression of OmpA-ST with PTE-SC, however, greatly improved the overall PTE production levels by mitigating toxicity through exporting of the PTE-SC and greatly enhanced packaged enzyme stability against iterative cycles of freezing and thawing.

In the continuing search for effective treatments for cancer, here we report the rational enginee... more In the continuing search for effective treatments for cancer, here we report the rational engineering of a novel multifunctional nanoparticle that combines traditional chemotherapy with cell targeting and anti-cellular-adhesion functionalities to selectively target multiple myeloma (MM) cells and overcome cell adhesion-mediated drug resistance (CAM-DR). Anti-cellular-adhesion evolves as a promising target in oncology. VLA-4-mediated adhesion to the bone marrow extracellular matrix and stromal cells confers MM cells with CAM-DR. In our design, we used micellar nanoparticles as dynamic self-assembling scaffolds to present VLA-4-antagonist peptides and doxorubicin conjugates simultaneously to selectively target MM cells and to overcome CAM-DR. Doxorubicin was conjugated to the nanoparticles through an pH-sensitive hydrazone bond to prevent premature release and thus non-specific toxicity. Peptides were conjugated via a multifaceted synthetic procedure for generating precisely controlled number of targeting functionalities per nanoparticle. The nanoparticles, which exhibited a size of ∼20nm, were efficiently internalized by MM cells with an optimal peptide valency of 20 per micelle, and induced cytotoxicity to MM cells. Mechanistic studies revealed that nanoparticles induced DNA double strand breaks as evidenced by H2AX phosphorylation, and triggered apoptosis, which was associated with PARP and caspase-8 cleavage. Importantly, multifunctional nanoparticles were more efficacious than doxorubicin in the presence of fibronectin (IC50=0.15±0.04 μM and 0.42±0.09 μM, respectively), and overcame CAM-DR induced by adherence of MM cells to fibronectin. Finally, in a MM xenograft model, nanoparticles preferentially homed to MM tumors, with a ∼10 fold more drug accumulation when compared to doxorubicin, and demonstrated dramatic tumor growth inhibition with much reduced overall systemic toxicity. Taken together, we demonstrate the disease-driven engineering of a nanoparticle-based drug delivery system, enabling the model of an integrative approach in the treatment of MM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5686. doi:1538-7445.AM2012-5686

Scientific Reports, Apr 27, 2016

Bacteria possess innate machinery to transport extracellular cargo between cells as well as packa... more Bacteria possess innate machinery to transport extracellular cargo between cells as well as package virulence factors to infect host cells by secreting outer membrane vesicles (OMVs) that contain small molecules, proteins, and genetic material. These robust proteoliposomes have evolved naturally to be resistant to degradation and provide a supportive environment to extend the activity of encapsulated cargo. In this study, we sought to exploit bacterial OMV formation to package and maintain the activity of an enzyme, phosphotriesterase (PTE), under challenging storage conditions encountered for real world applications. Here we show that OMV packaged PTE maintains activity over free PTE when subjected to elevated temperatures (>100-fold more activity after 14 days at 37 °C), iterative freeze-thaw cycles (3.4-fold post four-cycles), and lyophilization (43-fold). We also demonstrate how lyophilized OMV packaged PTE can be utilized as a cell free reagent for long term environmental remediation of pesticide/chemical warfare contaminated areas.

Blood Cancer Journal, Apr 1, 2012

In the continuing search for effective cancer treatments, we report the rational engineering of a... more In the continuing search for effective cancer treatments, we report the rational engineering of a multifunctional nanoparticle that combines traditional chemotherapy with cell targeting and anti-adhesion functionalities. Very late antigen-4 (VLA-4) mediated adhesion of multiple myeloma (MM) cells to bone marrow stroma confers MM cells with cell-adhesion-mediated drug resistance (CAM-DR). In our design, we used micellar nanoparticles as dynamic self-assembling scaffolds to present VLA-4-antagonist peptides and doxorubicin (Dox) conjugates, simultaneously, to selectively target MM cells and to overcome CAM-DR. Dox was conjugated to the nanoparticles through an acid-sensitive hydrazone bond. VLA-4-antagonist peptides were conjugated via a multifaceted synthetic procedure for generating precisely controlled number of targeting functionalities. The nanoparticles were efficiently internalized by MM cells and induced cytotoxicity. Mechanistic studies revealed that nanoparticles induced DNA double-strand breaks and apoptosis in MM cells. Importantly, multifunctional nanoparticles overcame CAM-DR, and were more efficacious than Dox when MM cells were cultured on fibronectin-coated plates. Finally, in a MM xenograft model, nanoparticles preferentially homed to MM tumors with B10 fold more drug accumulation and demonstrated dramatic tumor growth inhibition with a reduced overall systemic toxicity. Altogether, we demonstrate the disease driven engineering of a nanoparticle-based drug delivery system, enabling the model of an integrative approach in the treatment of MM.

Journal of Visualized Experiments, Nov 16, 2016

Biomaterials, Jul 1, 2013

The conserved nucleotide binding site (NBS), found in the Fab variable domain of all antibody iso... more The conserved nucleotide binding site (NBS), found in the Fab variable domain of all antibody isotypes, remains a not-so-widely known and under-utilized site. Here, we describe a UV photocrosslinking method (UV-NBS) that utilizes the NBS for site-specific covalent functionalization of antibodies, while preserving antibody activity. We identified a small molecule, indole-3-butyric acid (IBA), which has affinity for the NBS (K d ¼ 1e8 mM) and can be photocrosslinked to antibodies upon UV energy exposure. By synthesizing their IBA conjugated versions, we have successfully photocrosslinked various types of functional ligands to antibodies at the NBS, including affinity tags (biotin), fluorescent molecules (FITC), peptides (iRGD), and chemotherapeutics (paclitaxel). An optimal UV exposure of 1e2 J/cm 2 yielded the most efficient photocrosslinking and resulted in 1e2 conjugations per antibody, while preserving the antigen binding activity and Fc related functions. Analysis of the photocrosslinked conjugates using western blotting, mass spectrometry, and computational docking simulations demonstrated that the photocrosslinking specifically takes place at the Y/F42 residue in framework region 2 of the antibody light chain. Taken together, the UV-NBS method provides a practical, site-specific, and chemically efficient method to functionalize antibodies with significant implications in diagnostic and therapeutic settings.

Analytical Chemistry, Sep 7, 2012

The conserved nucleotide binding site (NBS), found within the Fab variable domain of antibodies, ... more The conserved nucleotide binding site (NBS), found within the Fab variable domain of antibodies, remains a not-so-widely known and underutilized site. Here we describe a novel affinity chromatography method that utilizes the NBS as a target for selectively purifying antibodies from complex mixtures. The affinity column was prepared by coupling indole butyric acid (IBA), which has a monovalent affinity for the NBS with a K d ranging between 1 and 8 μM, to ToyoPearl resin resulting in the NBS targeting affinity column (NBS IBA). The proof-of-concept studies performed using the chimeric pharmaceutical antibody rituximab demonstrated that antibodies were selectively captured and retained on the NBS IBA column and were successfully eluted by applying a mild NaCl gradient at pH 7.0. Furthermore, the NBS IBA column consistently yielded >95% antibody recovery with >98% purity, even when the antibody was purified from complex mixtures such as conditioned cell culture supernatant, hybridoma media, and mouse ascites fluid. The results presented in this study establish the NBS IBA column as a viable small-molecule-based affinity chromatography method for antibody purification with significant implications in industrial antibody production. Potential advantages of the NBS IBA platform are improved antibody batch quality, enhanced column durability, and reduced overall production cost.

The FASEB Journal, May 1, 2021

Des modes de realisation de l'invention concernent des systemes, des procedes et des composit... more Des modes de realisation de l'invention concernent des systemes, des procedes et des compositions pour l'administration d'un medicament a l'aide d'une nanoparticule a des cellules ou tissus cibles. Un systeme d'administration de medicament peut comprendre une nanoparticule ayant un composant de ciblage et un composant therapeutique. La nanoparticule peut avoir un nombre predetermine ou une valence predeterminee de molecules de ciblage pour une interaction multivalente avec une cellule ou un tissu cible. La liaison des molecules de ciblage a la cellule cible peut conduire a la capture a mediation par un recepteur de la nanoparticule par la cellule cible. Le compose therapeutique peut etre administre ulterieurement a l'interieur une vesicule endocytique de la cellule cible. L'invention concerne egalement des systemes d'administration d'un medicament a l'aide de nanoparticules tels que decrits presentement pouvant permettre une efficacite ame...

American Journal of Respiratory Cell and Molecular Biology, Dec 1, 2020

Biosensors and Bioelectronics, Nov 1, 2013

The nucleotide binding site (NBS) is an under-utilized, highly conserved binding site found withi... more The nucleotide binding site (NBS) is an under-utilized, highly conserved binding site found within the variable region of nearly all antibody Fab arms. Here, we describe an NBS specific UV photocrosslinking biotinylation method (UV-NBS Biotin) for the oriented immobilization of antibodies to streptavidin-coated surfaces, such that the antigen binding activity remains unaffected. An optimal UV exposure of 1 J/cm 2 yielded an average conjugation efficiency of ∼1 biotin per antibody resulting in significant immobilization efficiency while maintaining maximal antigen binding activity. With the continued push for miniaturization of medical diagnostics to reduce cost and increase patient accessibility the ever shrinking on chip detection areas necessitate the highest level of immobilized antibody activity to maximize assay detection capabilities. The UV-NBS Biotin method yielded surfaces with significantly enhanced antigen detection capabilities, improved antigen detection sensitivity and the highest amount of active surface immobilized antibody when compared to other common immobilization methods including: ε-NH 3 + surface conjugation, NHS-Biotin, and direct physical adsorption. Taken together, the UV-NBS Biotin method provides a universal, site-specific immobilization method that is amenable to any available assay detection modality with potential significant implications in the development of miniaturized medical diagnostics and lab on a chip technologies.

Bioconjugate Chemistry, Jun 23, 2014

Described here is a UV photo-cross-linking method that utilizes the NBS (nucleotide binding site)... more Described here is a UV photo-cross-linking method that utilizes the NBS (nucleotide binding site) for site-specific covalent functionalization of antibodies with reactive thiol moieties (UV-NBS(Thiol)), while preserving antibody activity. By synthesizing an indole-3-butyric acid (IBA) conjugated version of cysteine we site-specifically photo-cross-linked a reactive thiol moiety to antibodies at the NBS. This thiol moiety can then be used as an orthogonally reactive location to conjugate various types of functional ligands that possess a thiol reactive group through disulfide bond formation or reaction with a maleimide functionalized ligand. Our results demonstrate the utility of the UV-NBS(Thiol) method by successfully functionalizing a prostate specific antigen antibody (IgG(PSA)) with IBA-Thiol and subsequent reaction with maleimide-fluorescein. An optimal UV energy of 0.5-1.5 J/cm(2) was determined to yield the most efficient photo-cross-linking and resulted in 1-1.5 conjugations per antibody while preserving antibody/antigen binding activity and Fc recognition. Utilizing the IBA-Thiol ligand allows for an efficient means of site-specifically conjugating UV sensitive functionalities to antibody NBS that would otherwise not have been amenable by the previously described UV-NBS photo-cross-linking method. The UV-NBS(Thiol) conjugation strategy can be utilized in various diagnostic and therapeutic applications with nearly limitless potential for the preparation of site-specific covalent conjugation of affinity tags, fluorescent molecules, peptides, and chemotherapeutics to antibodies.