High-Resolution Surface Replication of Living Organisms using Air-Through-Precursor Suction-Augmented Replica Molding.

Replica molding is widely used to reproduce the surface microstructures that provide living organisms with distinct and useful functions. However, the existing methods are limited by the low resolution resulting from the air trapped in the structures during precursor solution loading. This study investigated replica molding with an air-through-precursor suction (APS) process, which used a degassed polydimethylsiloxane substrate to remove the trapped air through the precursor solution. The liquid loading times are characterized using a model template, and air suction that is up to 36 times faster can be achieved using the APS process relative to a conventional method. Using APS replica molding, biocompatible replicates from human fingerprints and gecko skin are fabricated using only a 3 min precursor solution loading step. Owing to the enhanced and reproducible resolution from APS replica molding, for the first time, the structural changes in the foot of a living gecko at the microscale can be observed when standing on a horizontal or vertical surface.

Phosphorylcholine-based encoded hydrogel microparticles with enhanced fouling resistance for multiplex immunoassays.

Due to the growing interest in multiplex protein detection, encoded hydrogel microparticles have received attention as a possible path to high performance multiplex immunoassays through a combination of high multiplexing capability and enhanced binding kinetics. However, their practical operation in real complex samples is still limited because polyethylene glycol, which is the main component of hydrogel particles, suffers from oxidative damage and relatively high fouling properties in biochemical solutions. Here, we introduce poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-based encoded hydrogel microparticles to perform fouling-resistant multiplex immunoassays, where the anti-fouling characteristics are attributed to the zwitterionic PMPC. By applying a newly developed molding lithography technique, viscous PMPCs with low reactivity were successfully incorporated into the hydrogel network while maintaining uniformity and rigidity for use in multiplex immunoassays. Non-specific protein adsorption on the PMPC particles was reduced by about 37.5% compared to that of conventional PEG particles, which leads to better assay sensitivity. We also validate the multiplex capability of the PMPC particles by performing multiplex detection of two target proteins. Furthermore, we verify that the PMPC particles have a 70% enhancement in anti-fouling characteristics compared to PEG particles in human platelet-rich plasma, potentiating a practical immunoassay platform for clinical diagnosis.

Microfluidic Synthesis of pH-Sensitive Multicompartmental Microparticles for Multimodulated Drug Release.

Stimuli-responsive carriers releasing multiple drugs have been researched for synergistic combinatorial cancer treatment with reduced side-effects. However, previously used drug carriers have limitations in encapsulating multiple drug components in a single carrier and releasing each drug independently. In this work, pH-sensitive, multimodulated, anisotropic drug carrier particles are synthesized using an acid-cleavable polymer and stop-flow lithography. The particles exhibit a faster drug release rate at the acidic pH of tumors than at physiological pH, demonstrating their potential for tumor-selective drug release. The drug release rate of the particles can be adjusted by controlling the monomer composition. To accomplish multimodulated drug release, multicompartmental particles are synthesized. The drug release profile of each compartment is programmed by tailoring the monomer composition. These pH-sensitive, multicompartmental particles are promising drug carriers enabling tumor-selective and multimodulated release of multiple drugs for synergistic combination cancer therapy.

A digital twin model for evidence-based clinical decision support in multiple myeloma treatment.

The treatment landscape for multiple myeloma (MM) has experienced substantial progress over the last decade. Despite the efficacy of new substances, patient responses tend to still be highly unpredictable. With increasing cognitive burden that is introduced through a complex and evolving treatment landscape, data-driven assistance tools are becoming more and more popular. Model-based approaches, such as digital twins (DT), enable simulation of probable responses to a set of input parameters based on retrospective observations. In the context of treatment decision-support, those mechanisms serve the goal to predict therapeutic outcomes to distinguish a favorable option from a potential failure. In the present work, we propose a similarity-based multiple myeloma digital twin (MMDT) that emphasizes explainability and interpretability in treatment outcome evaluation. We've conducted a requirement specification process using scientific literature from the medical and methodological domains to derive an architectural blueprint for the design and implementation of the MMDT. In a subsequent stage, we've implemented a four-layer concept where for each layer, we describe the utilized implementation procedure and interfaces to the surrounding DT environment. We further specify our solutions regarding the adoption of multi-line treatment strategies, the integration of external evidence and knowledge, as well as mechanisms to enable transparency in the data processing logic. Furthermore, we define an initial evaluation scenario in the context of patient characterization and treatment outcome simulation as an exemplary use case for our MMDT. Our derived MMDT instance is defined by 475 unique entities connected through 438 edges to form a MM knowledge graph. Using the MMRF CoMMpass real-world evidence database and a sample MM case, we processed a complete outcome assessment. The output shows a valid selection of potential treatment strategies for the integrated medical case and highlights the potential of the MMDT to be used for such applications. DT models face significant challenges in development, including availability of clinical data to algorithmically derive clinical decision support, as well as trustworthiness of the evaluated treatment options. We propose a collaborative approach that mitigates the regulatory and ethical concerns that are broadly discussed when automated decision-making tools are to be included into clinical routine.

Discontinuous Dewetting in a Degassed Mold for Fabrication of Homogeneous Polymeric Microparticles.

Discontinuous dewetting (DD) is an attractive technique that enables the production of large liquid arrays in microwells and is applicable to the synthesis of anisotropic microparticles with complex morphologies. However, such loading of liquids into microwells presents a significant challenge, as the liquids used in this technique should exhibit low mold surface wettability. This study introduces DD in a degassed mold (DM), a simple yet powerful technique that achieves uniform loading of microparticle precursors into large microwell arrays within 1 min. Using this technique, hydrogel microparticles are produced by different polymerization mechanisms with various shapes and sizes, ranging from a few micrometers to hundreds of micrometers. Hydrophobic oil microparticles are produced by the simple plasma treatment of the DM, and agarose microparticles encapsulating bovine serum albumin (in a well-dispersed state) are produced by submerging the DM in fluorinated oil. To demonstrate additional functionality of microparticles using this technique, high concentrations of magnetic nanoparticles are loaded into microparticles for particle-based immunoassays performed in a microwell plate, and the immunoassay performance is comparable to that of ELISA.

Degassed micromolding lithography for rapid fabrication of anisotropic hydrogel microparticles with high-resolution and high uniformity.

Replica molding techniques, which are used to synthesize microparticles inside anisotropic micromolds, have been developed to enable the mass production of hydrogel particles. However, these techniques are limited in their ability to synthesize only a narrow range of particle compositions and shapes because of the difficulty in loading precursors into the micromolds as well as the low particle homogeneity due to the uneven evaporation of the precursors. Herein, we describe a simple yet powerful technique, called degassed micromolding lithography, which can load precursors within 1 min regardless of the wettability. This technique is based on the gas-solubility of a degassed micromold that acts as a suction pump to completely fill the mold by drawing precursor liquids in. The semi-closed system within the micromold prevents the uneven evaporation of the precursor, which is essential for the production of homogeneous particles. Furthermore, controlled uniformity of the hydrogel microparticles (C.V. < 2%) can be achieved by engineering the design of the micromold array.

Precipitation-based colorimetric multiplex immunoassay in hydrogel particles.

Despite a growing demand for more accessible diagnostic technologies, current methods struggle to simultaneously detect multiple analytes with acceptable sensitivity and portability. Colorimetric assays have been widely used due to their simplicity of signal readout, but the lack of multiplexibility has been a perpetual constraint. Meanwhile, particle-based assays offer multiplex detection by assigning an identity code to each analyte, but they often require lab-based equipment unsuitable for portable diagnostics. Here, by merging the two approaches, this paper reports a colorimetric multiplex immunoassay based on hydrogel microparticles that achieves the best of both worlds. The low-cost portable multiplex assay demonstrates sensitivities as high as and dynamic ranges greater than the lab-based enzyme-linked immunosorbent assay (ELISA). These critical advances are made possible by local precipitation and amplification of insoluble colour dyes inside the hydrogel networks. For the first time, enzymatic accumulation of colour dyes in hydrogel particles is reported and the kinetics of colour development is characterized in this work. By taking advantage of the colour signals in the visible spectrum, the hydrogel microparticles were imaged and analysed using low-cost portable devices. The colorimetric multiplex immunoassay was used to successfully detect three target biomarkers of preeclampsia and validated clinically using healthy and patient-derived plasma samples.

Affinity-Enhanced CTC-Capturing Hydrogel Microparticles Fabricated by Degassed Mold Lithography.

Technologies for the detection and isolation of circulating tumor cells (CTCs) are essential in liquid biopsy, a minimally invasive technique for early diagnosis and medical intervention in cancer patients. A promising method for CTC capture, using an affinity-based approach, is the use of functionalized hydrogel microparticles (MP), which have the advantages of water-like reactivity, biologically compatible materials, and synergy with various analysis platforms. In this paper, we demonstrate the feasibility of CTC capture by hydrogel particles synthesized using a novel method called degassed mold lithography (DML). This technique increases the porosity and functionality of the MPs for effective conjugation with antibodies. Qualitative fluorescence analysis demonstrates that DML produces superior uniformity, integrity, and functionality of the MPs, as compared to conventional stop flow lithography (SFL). Analysis of the fluorescence intensity from porosity-controlled MPs by each reaction step of antibody conjugation elucidates that more antibodies are loaded when the particles are more porous. The feasibility of selective cell capture is demonstrated using breast cancer cell lines. In conclusion, using DML for the synthesis of porous MPs offers a powerful method for improving the cell affinity of the antibody-conjugated MPs.

Photopolymerization-Based Synthesis of Uniform Magnetic Hydrogels and Colorimetric Glucose Detection.

Magnetic hydrogels have been commonly used in biomedical applications. As magnetite nanoparticles (MNPs) exhibit peroxidase enzyme-like activity, magnetic hydrogels have been actively used as signal transducers for biomedical assays. Droplet microfluidics, which uses photoinitiated polymerization, is a preferred method for the synthesis of magnetic hydrogels. However, light absorption by MNPs makes it difficult to obtain fully polymerized and homogeneous magnetic hydrogels through photoinitiated polymerization. Several methods have been reported to address this issue, but few studies have focused on investigating the light absorption properties of photoinitiators. In this study, we developed a simple method for the synthesis of poly(ethylene glycol) (PEG)-based uniform magnetic hydrogels that exploits the high ultraviolet absorption of a photoinitiator. Additionally, we investigated this effect on shape deformation and structural uniformity of the synthesized magnetic hydrogels. Two different photoinitiators, Darocur 1173 and lithium phenyl (2,4,6-trimethylbenzoyl) phosphinate (LAP), with significantly different UV absorption properties were evaluated based on the synthesis of magnetic hydrogels. The magnetic characteristics of the PEG-stabilized MNPs in hydrogels were investigated with a vibrating sample magnetometer. Finally, the colorimetric detection of hydrogen peroxide and glucose was conducted based on the enzyme-like property of MNPs and repeated several times to observe the catalytic activity of the magnetic hydrogels.

Multiplexed immunoassay using post-synthesis functionalized hydrogel microparticles.

In response to a growing demand for simultaneous detection of multiple proteins in a single sample, multiplex immunoassay platforms have emerged at the forefront of proteomic analysis. In particular, detections using graphically encoded hydrogel microparticles synthesized via flow lithography have received attention for integrating a hydrogel, a substrate that can provide enhanced kinetics and high loading capacity, into the bead-based multiplex platform. Currently, the method of microparticle functionalization involves copolymerization of antibodies with the gel during particle synthesis. However, its practical operation is too precarious to be adopted because antibodies are susceptible to aggregation due to incompatibility with hydrophobic photoinitiators used in the photo-induced gel polymerization. In this work, we present a multiplex immunoassay platform that uses encoded hydrogel microparticles that are functionalized after particle synthesis by conjugating antibodies with remnant active groups readily available in the hydrogels. The method not only precludes antibody aggregation but also augments the loading density of the antibodies, which translates into enhanced detection performance. In addition to multiplexing, our platform demonstrates high sensitivity, a broad assay range, and a fast detection rate that outperform the enzyme linked immunosorbent assay (ELISA).

Fabrication of dual stimuli-responsive multicompartmental drug carriers for tumor-selective drug release.

There has been increasing attention to the development of multi-stimuli-responsive drug carriers for precisely controlled drug release at target disease areas. In this study, pH- and redox-responsive hybrid drug carriers were fabricated by using both ketal-based acid-cleavable precursors and disulfide-based reducible precursors via stop-flow lithography. pH- and redox-sensitive drug release of the dual stimuli-responsive hybrid particles was confirmed, demonstrating their feasibility for selective and efficient drug release into tumor tissues in acidic and highly reductive environments. It was also found that the drug release rate of the particles was fine-tuned by modulating monomer compositions in the precursor. Importantly, the dual stimuli-responsive hybrid particles exhibited synergistic, controlled drug release in complex stimuli (both pH and redox stimuli) environments. To achieve tumor-selective combination chemotherapy, multicompartmental drug carriers consist of an acid-degradable compartment and a reducible compartment, which can separately encapsulate individual model drugs in each of the compartments. The multicompartmental particles exhibited independent drug release upon exposure to the corresponding stimulus. The dual stimuli-responsive, multicompartmental particles are effective drug carriers for tumor-selective release of a drug cocktail, leading to synergistic combination chemotherapy.

Microfluidic fabrication of biocompatible poly(N-vinylcaprolactam)-based microcarriers for modulated thermo-responsive drug release.

Various thermo-responsive polymers have been developed for controlled drug delivery upon the local application of external heat. The development of thermo-responsive polymers with high biocompatibility and tunable thermo-sensitivity is crucial for safe and efficient therapeutic application. In this study, thermo-responsive drug carriers featuring tunable thermo-sensitivities were synthesized using biocompatible poly(N-vinyl caprolactam) (PVCL) and stop-flow lithography. The PVCL-based particles showed selective drug release depending on temperature, illustrating their feasibility for on-demand controlled drug delivery. The volume phase transition temperature (VPTT) of the PVCL-based particles can be adjusted to vary from room temperature to body temperature by controlling their monomer compositions. In addition, modulated drug release was achieved by constructing multicompartments of different thermo-sensitivities within the PVCL particles. To accomplish thermo-responsive anticancer therapy, doxorubicin (DOX) was encapsulated into the PVCL particles as an anticancer drug. The DOX-loaded PVCL particles exhibited both thermo-responsive drug release and anticancer activity. This study demonstrates that thermo-responsive PVCL particles are highly promising carriers for safe and targeted anticancer therapy.