Design and evaluation of nanoscale materials with programmed responsivity towards epigenetic enzymes.

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly(acetyl L-lysine) and poly(ethylene glycol) blocks.

Ion transport in muscle acetylcholine receptor maintained by conserved salt bridges between the pore and lipid membrane.

Pores through ion channels rapidly transport small inorganic ions along their electrochemical gradients. Here, applying single-channel electrophysiology and mutagenesis to the archetypal muscle nicotinic acetylcholine receptor (AChR) channel, we show that a conserved pore-peripheral salt bridge partners with those in the other subunits to regulate ion transport. Disrupting the salt bridges in all five receptor subunits greatly decreases the amplitude of the unitary current and increases its fluctuations.

Design and Evaluation of Nanoscale Materials with Programmed Responsivity towards Epigenetic Enzymes.

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly (acetyl L-lysine) and poly(ethylene glycol) blocks.

Acquired αSMA Expression in Pericytes Coincides with Aberrant Vascular Structure and Function in Pancreatic Ductal Adenocarcinoma.

The subpopulations of tumor pericytes undergo pathological phenotype switching, affecting their normal function in upholding structural stability and cross-communication with other cells. In the case of pancreatic ductal adenocarcinoma (PDAC), a significant portion of blood vessels are covered by an α-smooth muscle actin (αSMA)-expressing pericyte, which is normally absent from capillary pericytes. The DesminαSMA phenotype was significantly correlated with intratumoral hypoxia and vascular leakiness.

Modified Bovine Milk Exosomes for Doxorubicin Delivery to Triple-Negative Breast Cancer Cells.

Biological nanoparticles, such as exosomes, offer an approach to drug delivery because of their innate ability to transport biomolecules. Exosomes are derived from cells and an integral component of cellular communication. However, the cellular cargo of human exosomes could negatively impact their use as a safe drug carrier.

Single-Molecule Force Probing of RGD-Binding Integrins on Pancreatic Cancer Cells.

Integrin-targeting arginine-glycine-aspartic acid (RGD)-based nanocarriers have been widely used for tumor imaging, monitoring of tumor development, and delivery of anticancer drugs. However, the thermodynamics of an RGD-integrin formation and dissociation associated with binding dynamics, affinity, and stability remains unclear. Here, we probed the binding strength of the binary complex to live pancreatic cancer cells using single-molecule binding force spectroscopy methods, in which RGD peptides were functionalized on a force probe tip through poly(ethylene glycol) (PEG)-based bifunctional linker molecules.

Dynamic cellular biomechanics in responses to chemotherapeutic drug in hypoxia probed by atomic force spectroscopy.

The changes in cellular structure play an important role in cancer cell development, progression, and metastasis. By exploiting single-cell, force spectroscopy methods, we probed biophysical and biomechanical kinetics (stiffness, morphology, roughness, adhesion) of brain, breast, prostate, and pancreatic cancer cells with standard chemotherapeutic drugs in normoxia and hypoxia over 12-24 hours. After exposure to the drugs, we found that brain, breast, and pancreatic cancer cells became approximately 55-75% less stiff, while prostate cancer cells became more stiff, due to either drug-induced disruption or reinforcement of cytoskeletal structure.

Different Single-Enzyme Conformational Dynamics upon Binding Hydrolyzable or Nonhydrolyzable Ligands.

Single-molecule measurements of protein dynamics help unveil the complex conformational changes and transitions that occur during ligand binding and catalytic processes. Using high-resolution single-molecule nanocircuit techniques, we have investigated differences in the conformational dynamics and transitions of lysozyme interacting with three ligands: peptidoglycan substrate, substrate-based chitin analogue, and indole derivative inhibitors. While processing peptidoglycan, lysozyme followed one of the two mechanistic pathways for the hydrolysis of the glycosidic bonds: a concerted mechanism inducing direct conformational changes from open to fully closed conformations or a nonconcerted mechanism involving transient pauses in intermediate conformations between the open and closed conformations.

Size-Tunable Metal-Organic Framework-Coated Magnetic Nanoparticles for Enzyme Encapsulation and Large-Substrate Biocatalysis.

Immobilizing enzymes on nanoparticles (NPs) enhances the cost-efficiency of biocatalysis; however, when the substrates are large, it becomes difficult to separate the enzyme@NP from the products while avoiding leaching or damage of enzymes in the reaction medium. Metal-organic framework (MOF)-coated magnetic NPs (MNPs) offer efficient magnetic separation and enhanced enzyme protection; however, the involved enzymes/substrates have to be smaller than the MOF apertures. A potential solution to these challenges is coprecipitating metal/ligand with enzymes on the MNP surface, which can partially bury (protect) the enzyme below the composite surface while exposing the rest of the enzyme to the reaction medium for catalysis of larger substrates.

Enzyme Immobilization on Graphite Oxide (GO) Surface via One-Pot Synthesis of GO/Metal-Organic Framework Composites for Large-Substrate Biocatalysis.

Although enzyme immobilization has improved many areas, biocatalysis involving large-size substrates is still challenging for immobilization platform design because of the protein damage under the often "harsh" reaction conditions required for these reactions. Our recent efforts indicate the potential of using Metal-Organic Frameworks (MOFs) to partially confine enzymes on the surface of MOF-based composites while offering sufficient substrate contact. Still, improvements are required to expand the feasible pH range and the efficiency of contacting substrates.

Size-Transformable, Multifunctional Nanoparticles from Hyperbranched Polymers for Environment-Specific Therapeutic Delivery.

Hyperbranched polymer-derived drug nanocarriers have been synthesized that can change sizes selectively in response to pH. These constructs were composed of tertiary amine-conjugated polycarbonate blocks "grafted from" a hyperbranched polyester polyol core. At neutral pH, unprotonated polycarbonate arms stabilized the copolymer aggregates in the form of nanoparticles with hydrodynamic diameters ranging from 150 to 190 nm.