Bifunctional Janus Microparticles with Spatially Segregated Proteins

The complement system is an integral component of the humoral immune system, and describes a cascade of interacting proteins responsible for the opsonization and lysis of foreign pathogens, in addition to the recruitment of immune cells. However, complement activation is also implicated in the progression and complication of immune dysfunctions such as sepsis. Microparticle (MP) biomaterials capable of tuning the local magnitude of serum complement activation could improve complement-mediated cytotoxicity to serum-resistant bacteria or calm an overactive immune response during sepsis. We demonstrate that model Fc-functionalized microparticles can be designed to either enhance or diminish the local cytotoxic effect of complement activation in human serum. The particles were formed with either the antibody Fc domains oriented outward from the particle surface or randomly adsorbed in a non-oriented fashion. In the oriented Fc form, complement products were directly sequestered to the particle surface, including C5a, a potent anaphylatoxin that, when elevated, is associated with poor sepsis prognosis. The oriented particle also lowered the cytotoxicity of serum and thus decreased the antibiotic effect when compared to serum alone. Conversely, the non-oriented microparticles were found to sequester similar levels of C5a, but much lower levels of iC3b and TCC on the microparticle surface, thereby increasing the amount of the soluble terminal complement complex. In addition, the non-oriented microparticles extend the distance over which TCC forms and enhance serum cytotoxicity to bacteria. Together, these two types of complement-modulating particles provide the first biomaterial that can functionally modify the range of complement activation at sites distant from the particle surface. Thus, biomaterials that exploit Fc presentation provide new possibilities to functionally modulate complement activation to achieve a desired clinical result.

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“…In addition, targeting the complement activation to specific bacteria types may improve future selectivity in the antibiotic effect. 72 …”

Section: Resultsmentioning

confidence: 99%

Fc microparticles can modulate the physical extent and magnitude of complement activity

et al. 2017

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“…Functionalization with FITC-BSA is a relatively simple functionalization process, and over several repetitions, the total time saved by researchers can be enormous. Future robots can also be designed for more complicated functionalization processes, including attaching multiple proteins to Janus particles, 3,8 modifying the system for solid phase synthesis, or functionalizing cells. In the case of clinical environments, using the robot to functionalize cellular samples with antibody or chemical labels can also prove highly valuable.…”

Section: Discussionmentioning

confidence: 99%

A Liquid-Handling Robot for Automated Attachment of Biomolecules to Microbeads

Enten

Yang

et al. 2016

SLAS Technology

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Diagnostics, drug delivery, and other biomedical industries rely on cross-linking ligands to microbead surfaces. Microbead functionalization requires multiple steps of liquid exchange, incubation, and mixing, which are laborious and time intensive. Although automated systems exist, they are expensive and cumbersome, limiting their routine use in biomedical laboratories. We present a small, bench-top robotic system that automates microparticle functionalization and streamlines sample preparation. The robot uses a programmable microcontroller to regulate liquid exchange, incubation, and mixing functions. Filters with a pore diameter smaller than the minimum bead diameter are used to prevent bead loss during liquid exchange. The robot uses three liquid reagents and processes up to 107 microbeads per batch. The effectiveness of microbead functionalization was compared with a manual covalent coupling process and evaluated via flow cytometry and fluorescent imaging. The mean percentages of successfully functionalized beads were 91% and 92% for the robot and manual methods, respectively, with less than 5% bead loss. Although the two methods share similar qualities, the automated approach required approximately 10 min of active labor, compared with 3 h for the manual approach. These results suggest that a low-cost, automated microbead functionalization system can streamline sample preparation with minimal operator intervention.

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“…Janus particles generated by this method typically display different surface chemistries on their two hemispheres, and therefore molecules can be selectively conjugated onto one side. 14, 34, 59 If chemically homogeneous Janus particles are desired, the metal side can be further coated with the same materials that the particles are composed of. This method, however, is limited to particles larger than a few hundred of nanometers, because smaller particles tend to be “bridged” by the metal coating.…”

Section: A Brief Overview Of Strategies For Fabricating Janus Partmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Janus particles for biological imaging and sensing

Sanchez

Gao

et al. 2016

Analyst

158

146

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Janus particles, named after the two-faced Roman god Janus, have different surface makeups, structures or compartments on two sides. This review highlights recent advances in employing Janus particles as novel analytical tools for live cell imaging and biosensing. Unlike conventional particles used in analytical science, two-faced Janus particles provide asymmetry and directionality, and can combine different or even incompatible properties within a single particle. The broken symmetry enables imaging and quantification of rotational dynamics, revealing information beyond what traditional measurements offer. The spatial segregation of molecules on the surface of a single particle also allows analytical functions that would otherwise interfere with each other to be decoupled, opening up opportunities for novel multimodal analytical methods. We summarize here the development of Janus particles, a few general methods for their fabrication and, more importantly, the emerging and novel applications of Janus particles as multi-functional imaging probes and sensors.

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Bifunctional Janus Microparticles with Spatially Segregated Proteins

Cited by 32 publications

References 23 publications

Fc microparticles can modulate the physical extent and magnitude of complement activity

Fc microparticles can modulate the physical extent and magnitude of complement activity

A Liquid-Handling Robot for Automated Attachment of Biomolecules to Microbeads

Janus particles for biological imaging and sensing

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