Design of an Anti-HMGB1 Synthetic Antibody for Ischemic/Reperfusion Injury Therapy.

High-mobility group box 1 (HMGB1) is a multifunctional protein. Upon injury or infection, HMGB1 is passively released from necrotic and activated dendritic cells and macrophages, where it functions as a cytokine, acting as a ligand for RAGE, a major receptor of innate immunity stimulating inflammation responses including the pathogenesis of cerebral ischemia/reperfusion (I/R) injury. Blocking the HMGB1/RAGE axis offers a therapeutic approach to treating these inflammatory conditions.

Cooling-induced, localized release of cytotoxic peptides from engineered polymer nanoparticles in living mice for cancer therapy.

Temperature-responsive polymers are often characterized by an abrupt change in the degree of swelling brought about by small changes in temperature. Polymers with a lower critical solution temperature (LCST) in particular, are important as drug and gene delivery vehicles. Drug molecules are taken up by the polymer in their solvent swollen state below their LCST.

Synthetic hydrogel nanoparticles for sepsis therapy.

Sepsis is a life-threatening condition caused by the extreme release of inflammatory mediators into the blood in response to infection (e.g., bacterial infection, COVID-19), resulting in the dysfunction of multiple organs.

Metal-Free Polymer-Based Affinity Medium for Selective Purification of His6-Tagged Proteins.

We report a metal free synthetic hydrogel copolymer with affinity and selectivity for His6-tagged peptides and proteins. Small libraries of copolymers incorporating charged and hydrophobic functional groups were screened by an iterative process for His6 peptide affinity. The monomer selection was guided by interactions found in the crystal structure of an anti-His tag antibody-His6 peptide antigen complex.

A new approach for IR spectra matching using normalized local change.

Spectra matching is widely used in various applications including the search for a spectrum of an unknown compound in an existing spectral database and quality control by means of comparing the spectra of products with standards. In this article, we present a new approach for calculating the similarities of Fourier-transform infrared (FTIR) spectra of organic compounds. Our method, named normalized local change (NLC) approach, incrementally calculates the spectral similarity based on the local spectral shapes.

Engineering the Binding Kinetics of Synthetic Polymer Nanoparticles for siRNA Delivery.

The affinity of a synthetic polymer nanoparticle (NP) to a target biomacromolecule is determined by the association and dissociation rate constants (, ) of the interaction. The individual rates and their sensitivity to local environmental influences are important factors for the on-demand capture and release a target biomacromolecule. Positively charged NPs for small interfering RNA (siRNA) delivery is a case in point.

X-ray structure of the direct electron transfer-type FAD glucose dehydrogenase catalytic subunit complexed with a hitchhiker protein.

The bacterial flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase complex derived from Burkholderia cepacia (BcGDH) is a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. In this study, the X-ray structure of BcGDHγα, the catalytic subunit (α-subunit) of BcGDH complexed with a hitchhiker protein (γ-subunit), was determined. The most prominent feature of this enzyme is the presence of the 3Fe-4S cluster, which is located at the surface of the catalytic subunit and functions in intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit.

Sequestering and inhibiting a vascular endothelial growth factor in vivo by systemic administration of a synthetic polymer nanoparticle.

Protein affinity reagents (PARs), frequently antibodies, are essential tools for basic research, diagnostics, separations and for clinical applications. However, there is growing concern about the reproducibility, quality and cost of recombinant and animal-derived antibodies. This has prompted the development of alternatives that could offer economic, and time-saving advantages without the use of living organisms.

Elucidation of the intra- and inter-molecular electron transfer pathways of glucoside 3-dehydrogenase.

Glucoside 3‑dehydrogenase (G3DH) is a flavin adenine dinucleotide (FAD)-containing oxidoreductase that catalyzes the oxidation of the hydroxy group on the C-3 position of pyranose and shows broad substrate specificity by oxidizing many saccharides. Due to unique site specificity and wide substrate specificity, G3DHs can be used for synthesis of sugar derivatives, anodic catalysis in biofuel cells, multi-sugar analysis using enzyme electrode, and for enzymatic detection of 1,5‑anhydro‑d‑glucitol, a clinical marker for diabetes. However, few studies have focused on the fundamental biochemical properties of G3DH, including its electron transfer pathway.

A polymer nanoparticle with engineered affinity for a vascular endothelial growth factor (VEGF).

Protein affinity reagents are widely used in basic research, diagnostics and separations and for clinical applications, the most common of which are antibodies. However, they often suffer from high cost, and difficulties in their development, production and storage. Here we show that a synthetic polymer nanoparticle (NP) can be engineered to have many of the functions of a protein affinity reagent.

An Fe-S cluster in the conserved Cys-rich region in the catalytic subunit of FAD-dependent dehydrogenase complexes.

Several bacterial flavin adenine dinucleotide (FAD)-harboring dehydrogenase complexes comprise three distinct subunits: a catalytic subunit with FAD, a cytochrome c subunit containing three hemes, and a small subunit. Owing to the cytochrome c subunit, these dehydrogenase complexes have the potential to transfer electrons directly to an electrode. Despite various electrochemical applications and engineering studies of FAD-dependent dehydrogenase complexes, the intra/inter-molecular electron transfer pathway has not yet been revealed.

Measuring melittin uptake into hydrogel nanoparticles with near-infrared single nanoparticle surface plasmon resonance microscopy.

This paper describes how changes in the refractive index of single hydrogel nanoparticles (HNPs) detected with near-infrared surface plasmon resonance microscopy (SPRM) can be used to monitor the uptake of therapeutic compounds for potential drug delivery applications. As a first example, SPRM is used to measure the specific uptake of the bioactive peptide melittin into N-isopropylacrylamide (NIPAm)-based HNPs. Point diffraction patterns in sequential real-time SPRM differential reflectivity images are counted to create digital adsorption binding curves of single 220 nm HNPs from picomolar nanoparticle solutions onto hydrophobic alkanethiol-modified gold surfaces.

Preparation of abiotic polymer nanoparticles for sequestration and neutralization of a target peptide toxin.

Synthetic polymer nanoparticles (NPs) with intrinsic affinity for target biomacromolecules hold great promise in the development of novel tools for biological and biomedical research. We recently reported the design and synthesis of abiotic, synthetic polymer NPs with high intrinsic affinity for a peptide toxin melittin. The NP was selected by screening a small library of NPs (∼100 nm) composed of various ratios of monomers that contain functional groups complementary to the peptide melittin.

Characterization of molecularly imprinted polymer nanoparticles by photon correlation spectroscopy.

We follow template-binding induced aggregation of nanoparticles enantioselectively imprinted against (S)-propranolol, and the non-imprinted ones, using photon correlation spectroscopy (dynamic light scattering). The method requires no separation steps. We have characterized binding of (R,S)-propranolol to the imprinted polymers and determined the degree of non-specificity by comparing the specific binding with the results obtained using non-imprinted nanoparticles.

Polymer nanoparticle hydrogels with autonomous affinity switching for the protection of proteins from thermal stress.

We report a new material design concept for synthetic, thermally responsive poly(N-isopropylacrylamide)-based copolymer nanoparticle (NP) hydrogels, which protect proteins from thermal stress. The NP hydrogels bind and protect a target enzyme from irreversible activity loss upon exposure to heat but "autonomously" release the enzyme upon subsequent cooling of the solution. Incorporation of the optimized amount of negatively charged and hydrophobic comonomers to the NP hydrogels was key to achieve these desired functions.

Epitope discovery for a synthetic polymer nanoparticle: a new strategy for developing a peptide tag.

We describe a novel epitope discovery strategy for creating an affinity agent/peptide tag pair. A synthetic polymer nanoparticle (NP) was used as the "bait" to catch an affinity peptide tag. Biotinylated peptide tag candidates of varied sequence and length were attached to an avidin platform and screened for affinity against the polymer NP.

Particle deformation and concentration polarization in electroosmotic transport of hydrogels through pores.

In this article, we report detection of deformable, hydrogel particles by the resistive-pulse technique using single pores in a polymer film. The hydrogels pass through the pores by electroosmosis and cause formation of a characteristic shape of resistive pulses indicating the particles underwent dehydration and deformation. These effects were explained via a non-homogeneous pressure distribution along the pore axis modeled by the coupled Poisson-Nernst-Planck and Navier-Stokes equations.

Polymer nanoparticle-protein interface. Evaluation of the contribution of positively charged functional groups to protein affinity.

Cationic-functionalized polymer nanoparticles (NPs) show strikingly distinct affinities to proteins depending on the nature of the cationic functional group. N-Isopropylacrylamide (NIPAm) polymer NPs incorporating three types of positively charged functional groups (guanidinium, primary amino, and quaternary ammonium groups) were prepared by precipitation polymerization. The affinities to fibrinogen, a protein with an isoelectric point (pI) of 5.

Molecularly imprinted polymers for histamine recognition in aqueous environment.

Molecularly imprinted polymers (MIP) for histamine using methacrylic acid were developed and recognition mechanisms were thoroughly characterized for the first time in this study. The binding affinity of imprinted polymer with structurally related compounds was studied in organic and aqueous media, at various conditions. In organic media, MIP was found to bind histamine two and six times more than ranitidine and fluoxetine, respectively, whereas higher selectivity was observed in the case of dimentidene or disodium cromoglycate.

"Clickable" affinity ligands for effective separation of glycoproteins.

In this paper, we present a new modular approach to immobilize boronic acid ligands that can offer effective separation of glycoproteins. A new "clickable" boronic acid ligand was synthesized by introducing a terminal acetylene group into commercially available 3-aminophenyl boronic acid. The clickable ligand, 3-(prop-2-ynyloxycarbonylamino)phenylboronic acid (2) could be easily coupled to azide-functionalized hydrophilic Sepharose using Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction under mild condition.

Peptide-imprinted polymer microspheres prepared by precipitation polymerization using a single bi-functional monomer.

A single bi-functional monomer, N,O-bismethacryloyl ethanolamine (NOBE), was used in precipitation polymerization system to synthesize molecularly imprinted polymer (MIP) microspheres. Highly specific binding sites were obtained for N-terminal protected neuropeptides, Boc-Leu-enkephalin and Pyr-Leu-enkephalin. The use of NOBE allowed binding sites to be formed in polymer microspheres that are able to recognize target peptides through the consensus C-terminal sequence.

A simple method for preparation of molecularly imprinted nanofiber materials with signal transduction ability.

A simple electrospinning method is developed to introduce signal transduction ability into molecularly imprinted nanofibers.

Characterization of QCM sensor surfaces coated with molecularly imprinted nanoparticles.

Molecularly imprinted polymers (MIPs) are gaining great interest as tailor-made recognition materials for the development of biomimetic sensors. Various approaches have been adopted to interface MIPs with different transducers, including the use of pre-made imprinted particles and the in situ preparation of thin polymer layers directly on transducer surfaces. In this work we functionalized quartz crystal microbalance (QCM) sensor crystals by coating the sensing surfaces with pre-made molecularly imprinted nanoparticles.

Selective molecular adsorption using electrospun nanofiber affinity membranes.

Molecularly imprinted nanoparticles were encapsulated into polymer nanofibers with a simple electrospinning method. The composite nanofibers form non-woven mats that can be used as affinity membrane to greatly simplify solid phase extraction of drug residues in analytical samples. Upward 100% of propranolol-imprinted nanoparticles can be easily encapsulated into poly(ethylene terephthalate) nanofibers, ensuring the composite materials to have a high specific binding capacity.