Active Pulsatile Gels: From a Chemical Microreactor to a Polymeric Actuator.

We report on a synthesis protocol, experimental characterization, and theoretical modeling of active pulsatile Belousov-Zhabotinsky (BZ) hydrogels. Our two-step synthesis technique allows independent optimization of the geometry, the chemical, and the mechanical properties of BZ gels. We identify the role of the surrounding medium chemistry and gel radius for the occurrence of BZ gel oscillations, quantified by the Damköhler number, which is the ratio of chemical reaction to diffusion rates.

Robust and Reliable Fabrication of Gelatin Films Containing Micropatterned Opal Structures via Evaporative Deposition and Thermal Gelation.

Biopolymeric hydrogel materials containing tunable optical properties such as micropatterned artificial opal structures hold significant potential in various applications. Despite recent advances in fabrication techniques, simple, reliable, and tunable production of stimuli-responsive micropatterned opal hydrogels under mild conditions remains challenging. We report a simple micromolding-based evaporative deposition-thermal gelation technique for gelatin films that capture uniform opal micropatterns, aided by a potent aminopolysaccharide chitosan (CS) that provides binding affinity and structural stability.

Capsule-based colorimetric temperature monitoring system for customizable cold chain management.

The COVID-19 pandemic and the resulting supply chain disruption have rekindled crucial needs for safe storage and transportation of essential items. Despite recent advances, existing temperature monitoring technologies for cold chain management fall short in reliability, cost, and flexibility toward customized cold chain management for various products with different required temperature. In this work, we report a novel capsule-based colorimetric temperature monitoring system with precise and readily tunable temperature ranges.

Fine-tuning of MXene-nickel oxide-reduced graphene oxide nanocomposite bioelectrode: Sensor for the detection of influenza virus and viral protein.

Influenza viruses can cause epidemics through inter-human transmission, and the social consequences of viral transmission are incalculable. Current diagnostics for virus detection commonly relies on antibodies or nucleic acid as recognition reagent. However, a more advanced and general method for the facile development of new biosensors is increasing in demand.

Triple Emulsion-Based Rapid Microfluidic Production of Core-Shell Hydrogel Microspheres for Programmable Biomolecular Conjugation.

We report a simple and rapid microfluidic approach to produce core-shell hydrogel microspheres in a single step. We exploit triple emulsion drops with sacrificial oil layers that separate two prepolymer phases, forming poly(ethylene glycol)-based core-shell microspheres via photopolymerization followed by spontaneous removal of the oil layer. Our technique enables the production of monodisperse core-shell microspheres with varying dimensions of each compartment by independently and precisely controlled flow rates.

A Robust Fabrication Technique for Hydrogel Films Containing Micropatterned Opal Structures via Micromolding and an Integrated Evaporative Deposition-Photopolymerization Approach.

Opal-structured thin-film hydrogel materials with micropatterns hold great potential for utility in a wide range of sensing applications. Micropatterning offers key advantages such as ready addressability, high throughput assay, and multiplexing. However, controlled fabrication of such films in a rapid, inexpensive, and reliable manner remains a challenge.

Integrated Methods to Manufacture Hydrogel Microparticles with High Protein Conjugation Capacity and Binding Kinetics via Viral Nanotemplate Display.

Genetically modified tobacco mosaic virus (TMV) can serve as a potent nanotemplate for high capacity protein conjugation through covalent coupling to its coat proteins with precise nanoscale spacing. TMV's own genomic RNA can also be exploited for orientationally controlled assembly onto various platforms with sequence and spatial selectivity via nucleic acid hybridization. Here we describe detailed methods for fabrication of hydrogel microparticles with capture DNA sequences, chemical activation and programming of TMV templates, TMV assembly with the microparticles and protein conjugation via bio-orthogonal click reactions.

Integrated Methods to Manufacture Hydrogel Microparticles Containing Viral-Metal Nanocomplexes with High Catalytic Activity.

Controlled synthesis of small and catalytically active noble metal nanoparticles under mild aqueous conditions is an unmet challenge. Genetically modified tobacco mosaic virus (TMV) can serve as a preferential precursor adsorption and growth sites for the controlled synthesis of palladium (Pd) nanoparticles with high catalytic activity. Here we describe detailed methods for the synthesis of Pd-TMV nanocomplexes as well as their integration into polymeric hydrogel microparticle platforms with controlled dimensions via a simple replica molding process.

High-throughput double emulsion-based microfluidic production of hydrogel microspheres with tunable chemical functionalities toward biomolecular conjugation.

Chemically functional hydrogel microspheres hold significant potential in a range of applications including biosensing, drug delivery, and tissue engineering due to their high degree of flexibility in imparting a range of functions. In this work, we present a simple, efficient, and high-throughput capillary microfluidic approach for controlled fabrication of monodisperse and chemically functional hydrogel microspheres via formation of double emulsion drops with an ultra-thin oil shell as a sacrificial template. This method utilizes spontaneous dewetting of the oil phase upon polymerization and transfer into aqueous solution, resulting in poly(ethylene glycol) (PEG)-based microspheres containing primary amines (chitosan, CS) or carboxylates (acrylic acid, AA) for chemical functionality.

Improved Protein Conjugation with Uniform, Macroporous Poly(acrylamide-co-acrylic acid) Hydrogel Microspheres via EDC/NHS Chemistry.

We demonstrate a robust and tunable micromolding method to fabricate chemically functional poly(acrylamide-co-acrylic acid) (p(AAm-co-AA)) hydrogel microspheres with uniform dimensions and controlled porous network structures for rapid biomacromolecular conjugation. Specifically, p(AAm-co-AA) microspheres with abundant carboxylate functional groups are fabricated via surface-tension-induced droplet formation in patterned poly(dimethylsiloxane) molds and photoinduced radical polymerization. To demonstrate the chemical functionality, we enlisted rapid EDC/NHS (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS)) chemistry for fluorescent labeling of the microspheres with small-molecule dye fluorescein glycine amide.

Integrated fabrication-conjugation methods for polymeric and hybrid microparticles for programmable drug delivery and biosensing applications.

Functionalized polymeric microparticles possess significant potential for controlled drug delivery and biosensing applications, yet current fabrication techniques face challenges in simple and scalable fabrication and biofunctionalization. For programmable manufacture of biofunctional microparticles in a simple manner, we have developed robust micromolding methods combined with biopolymeric conjugation handles and bioorthogonal click reactions. In this focused minireview, we present detailed methods for our integrated approaches for fabrication of microparticles with controlled 2D and 3D shapes and dimensions toward controlled release, and for biomacromolecular conjugation via strain promoted alkyne-azide cycloaddition (SPAAC) and tetrazine-trans-cyclooctene (Tz-TCO) ligation reactions utilizing a potent aminopolysaccharide chitosan as an efficient conjugation handle.

Porosity-Tuned Chitosan-Polyacrylamide Hydrogel Microspheres for Improved Protein Conjugation.

We report a robust method to manufacture polyacrylamide-based functional hydrogel microspheres with readily tunable macroporous structures by utilizing a simple micromolding-based technique. Specifically, surface tension-induced droplet formation of aqueous solutions of chitosan and acrylamide in 2D-shaped micromolds followed by photoinduced polymerization leads to monodisperse microspheres. Pore sizes of the microspheres can be readily tuned by simple addition of inert long-chain poly(ethylene glycol) porogen at low content in the prepolymer solution.

Shape-Encoded Chitosan-Polyacrylamide Hybrid Hydrogel Microparticles with Controlled Macroporous Structures via Replica Molding for Programmable Biomacromolecular Conjugation.

Polymeric hydrogel microparticle-based suspension arrays with shape-based encoding offer powerful alternatives to planar and bead-based arrays toward high throughput biosensing and medical diagnostics. We report a simple and robust micromolding technique for polyacrylamide- (PAAm-) based biopolymeric-synthetic hybrid microparticles with controlled 2D shapes containing a potent aminopolysaccharide chitosan as an efficient conjugation handle uniformly incorporated in PAAm matrix. A postfabrication conjugation approach utilizing amine-reactive chemistries on the chitosan shows stable incorporation and retained chemical reactivity of chitosan, readily tunable macroporous structures via simple addition of low content long-chain PEG porogens for improved conjugation capacity and kinetics, and one-pot biomacromolecular assembly via bioorthogonal click reactions with minimal nonspecific binding.

Controlled Fabrication of Microparticles with Complex 3D Geometries by Tunable Interfacial Deformation of Confined Polymeric Fluids in 2D Micromolds.

Polymeric microparticles with complex shapes have attracted substantial attention in many application areas because particle shape is a critical parameter to impart programmable functionalities. The formation of specific three-dimensional (3D) microstructures in a simple, scalable, and controllable manner is difficult. Here, we report the controlled fabrication of microparticles with complex 3D shapes based on the simple tuning of mold swelling and capillarity.

Controlled fabrication of multicompartmental polymeric microparticles by sequential micromolding via surface-tension-induced droplet formation.

Polymeric multicompartmental microparticles have significant potential in many applications due to the capability to hold various functions in discrete domains within a single particle. Despite recent progress in microfluidic techniques, simple and scalable fabrication methods for multicompartmental particles remain challenging. This study reports a simple sequential micromolding method to produce monodisperse multicompartmental particles with precisely controllable size, shape, and compartmentalization.

An integrated approach for enhanced protein conjugation and capture with viral nanotemplates and hydrogel microparticle platforms via rapid bioorthogonal reactions.

We demonstrate significantly enhanced protein conjugation and target protein capture capacity by exploiting tobacco mosaic virus (TMV) templates assembled with hydrogel microparticles. Protein conjugation results with a red fluorescent protein R-Phycoerythrin (R-PE) show significantly enhanced protein conjugation capacity of TMV-assembled particles (TMV-particles) compared to planar substrates or hydrogel microparticles. In-depth examination of protein conjugation kinetics via tetrazine (Tz)-trans-cyclooctene (TCO) cycloaddition and strain-promoted alkyne-azide cycloaddition (SPAAC) reaction demonstrates that TMV-particles provide a less hindered environment for protein conjugation.

Facile strategy for protein conjugation with chitosan-poly(ethylene glycol) hybrid microparticle platforms via strain-promoted alkyne-azide cycloaddition (SPAAC) reaction.

We demonstrate a facile fabrication-conjugation scheme for protein-conjugated biosensing platforms. Specifically, we utilize a chitosan-poly(ethylene glycol) hybrid system to fabricate highly uniform and chemically reactive microparticle platforms via simple replica molding. Strain-promoted alkyne-azide cycloaddition (SPAAC) reaction between azide-modified proteins and microparticles activated with strain-promoted cyclooctynes allows tunable protein conjugation under mild reaction conditions.

A facile synthesis-fabrication strategy for integration of catalytically active viral-palladium nanostructures into polymeric hydrogel microparticles via replica molding.

The synthesis of small, uniform, well-dispersed and active Pd nanocatalysts under mild conditions in a predictable and controlled manner is an unmet challenge. Viral nanomaterials are attractive biotemplates for the controlled synthesis of nanoparticles due to their well-defined and monodisperse structure along with abundant surface functionalities. Here, we demonstrate spontaneous formation of small (1-2 nm), uniform and highly crystalline palladium (Pd) nanoparticles along genetically modified tobacco mosaic virus (TMV1cys) biotemplates without external reducing agents.

Fabrication of chitosan-poly(ethylene glycol) hybrid hydrogel microparticles via replica molding and its application toward facile conjugation of biomolecules.

We demonstrate a facile scheme to fabricate nonspherical chitosan-poly(ethylene glycol) (PEG) microparticle platforms for conjugation of biomolecules with high surface density. Specifically, we show that PEG microparticles containing short chitosan oligomers are readily fabricated via replica molding (RM). Fluorescence and FTIR microscopy results illustrate that these chitosan moieties are incorporated with PEG networks in a stable manner while retaining chemical reactivity toward amine-reactive chemistries.

Profiling surface glycans on live cells and tissues using quantum dot-lectin nanoconjugates.

The surface of mammalian cells is densely coated with complex glycans, which are directly involved in cell-cell or cell-protein interactions that trigger various biological responses. Here, we present a novel glycomics approach that uses quantum dot (Qdot)-lectin nanoconjugates to interrogate the surface glycans of tissues and patterned cells. Our approach allows highly sensitive in situ monitoring of specific lectin-glycan interactions and quantitative information on surface glycans for each examined cell line and tissue.

Biologically inspired strategy for programmed assembly of viral building blocks with controlled dimensions.

Facile fabrication of building blocks with precisely controlled dimensions is imperative in the development of functional devices and materials. We demonstrate the assembly of nanoscale viral building blocks of controlled lengths using a biologically motivated strategy. To achieve this we exploit the simple self-assembly mechanism of Tobacco mosaic virus (TMV), whose length is solely governed by the length of its genomic mRNA.

In situ small-angle X-ray scattering analysis of palladium nanoparticle growth on tobacco mosaic virus nanotemplates.

We present an examination of palladium (Pd) nanoparticle growth on genetically modified tobacco mosaic virus (TMV1cys) nanotemplates via in situ small-angle X-ray scattering (SAXS). Specifically, we examine the role of the TMV1cys templates in Pd nanoparticle formation through the electroless reduction of Pd precursor by a chemical reducing agent as compared to identical conditions in the absence of the TMV1cys templates. We show that in the presence of TMV1cys, the viral nanotemplates provide preferential growth sites for Pd nanoparticle formation, as no measurable Pd particle growth was observed in the bulk solution.

Microfluidic fabrication of complex-shaped microfibers by liquid template-aided multiphase microflow.

This study presents a simple microfluidic approach to the rapid fabrication of complex-shaped microfibers (e.g., single hollow, double hollow, and microbelt), with highly uniform structures, based on a combination of the spontaneous formation of polymeric jet streams and in situ photopolymerization.

LuxS coexpression enhances yields of recombinant proteins in Escherichia coli in part through posttranscriptional control of GroEL.

Cell-to-cell communication, or quorum sensing (QS), enables cell density-dependent regulation of bacterial gene expression which can be exploited for the autonomous-signal-guided expression of recombinant proteins (C. Y. Tsao, S.

Microfluidic fabrication of hydrogel microparticles containing functionalized viral nanotemplates.

We demonstrate rapid microfluidic fabrication of hybrid microparticles composed of functionalized viral nanotemplates directly embedded in polymeric hydrogels. Specifically, genetically modified tobacco mosaic virus (TMV) templates were covalently labeled with fluorescent markers or metalized with palladium (Pd) nanoparticles (Pd-TMV) and then suspended in a poly(ethylene glycol)-based solution. Upon formation in a flow-focusing device, droplets were photopolymerized with UV light to form microparticles.