3D Printed Customizable Microsampling Devices for Neuroscience Applications.

Multifunctional devices that incorporate chemical or physical measurements combined with ways to manipulate brain tissue via drug delivery, electrical stimulation, or light for optogenetics are desired by neuroscientists. The next generation in vivo brain devices will likely utilize the extensive flexibility and rapid processing of 3D printing. This Perspective demonstrates how close we are to this reality for advanced neuroscience measurements.

Attachment and optimization of Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa biofilms to a 3D printed lattice.

A lattice was designed and fabricated using three-dimensional (3D) printing that allows for the facile transfer of biofilms formed from either Staphylococcus aureus, Staphylococcus epidermidis, or Pseudomonas aeruginosa into a fresh cell culture flask. To enhance biofilm production onto the filaments, three protein-based treatments were compared: fetal bovine serum (FBS), bovine serum albumin (BSA), and fibrinogen (Fb). Protein treatments included either supplementing the growth broths or pre-coating the lattice prior to immersion into the broth.

Probing spatial inhomogeneity of cholinergic changes in cortical state in rat.

Acetylcholine (ACh) plays an essential role in cortical information processing. Cholinergic changes in cortical state can fundamentally change how the neurons encode sensory input and motor output. Traditionally, ACh distribution in cortex and associated changes in cortical state have been assumed to be spatially diffuse.

Microdialysis Sampling of Quorum Sensing Homoserine Lactones during Biofilm Formation.

Bacteria communicate chemically through a system called quorum sensing. In this work, microdialysis sampling procedures were optimized to collect quorum sensing molecules produced during in situ biofilm formation directly on the polymeric semipermeable membrane of the microdialysis probe. V.

In Situ Inner Lumen Attachment of Heparin to Poly(ether sulfone) Hollow Fiber Membranes Used for Microdialysis Sampling.

An in situ chemical surface modification method to attach heparin to the inner lumen of a single hollow fiber poly(ether sulfone) (PES) membrane incorporated into a commercial microdialysis sampling device is described. The immobilization process uses gentle, room-temperature conditions with the enzyme laccase (E.C.

Iloprost Affects Macrophage Activation and CCL2 Concentrations in a Microdialysis Model in Rats.

Purpose: The hypothesis that locally-released iloprost, a synthetic prostacyclin analog, affects macrophage phenotype at a microdialysis implant in the subcutaneous space of rats was tested. Macrophage activation towards alternatively-activated phenotypes using pharmaceutical release is of interest to improve integration of implants and direct the foreign body reaction toward a successful outcome.

Methods: Macrophage cell culture was used to test iloprost macrophage activation in vitro.

Thermoresponsive nanoparticle agglomeration/aggregation in salt solutions: Dependence on graft density.

Gold nanoparticles with a graft density of 0.09, 0.30 and 0.

Effects of delayed delivery of dexamethasone-21-phosphate via subcutaneous microdialysis implants on macrophage activation in rats.

Macrophage activation is of interest in the biomaterials field since macrophages with an M(Dex) characteristic phenotype, i.e., CD68(+)CD163(+), are believed to result in improved integration of the biomaterial as well as improved tissue remodeling and increased biomaterial longevity.

A review of flux considerations for in vivo neurochemical measurements.

The mass transport or flux of neurochemicals in the brain and how this flux affects chemical measurements and their interpretation is reviewed. For all endogenous neurochemicals found in the brain, the flux of each of these neurochemicals exists between sources that produce them and the sites that consume them all within μm distances. Principles of convective-diffusion are reviewed with a significant emphasis on the tortuous paths and discrete point sources and sinks.

Bioanalytical chemistry of cytokines--a review.

Cytokines are bioactive proteins produced by many different cells of the immune system. Due to their role in different inflammatory disease states and maintaining homeostasis, there is enormous clinical interest in the quantitation of cytokines. The typical standard methods for quantitation of cytokines are immunoassay-based techniques including enzyme-linked immusorbent assays (ELISA) and bead-based immunoassays read by either standard or modified flow cytometers.

Localized delivery of dexamethasone-21-phosphate via microdialysis implants in rat induces M(GC) macrophage polarization and alters CCL2 concentrations.

Microdialysis sampling probes were implanted into the subcutaneous space on the dorsal side of male Sprague Dawley rats to locally deliver dexamethasone-21-phosphate (Dex) with the aim of altering in vivo macrophage polarization. Macrophage polarization is of significant interest in the field of biomaterials since wound-healing macrophages are a possible means to extend implant life as well as improve tissue remodeling to an implant. Quantitative analysis of CCL2 in collected dialysates, gene expression and immunohistochemistry performed on the tissue surrounding the microdialysis implant were used to evaluate if Dex polarized macrophages.

In vivo microdialysis sampling of adipokines CCL2, IL-6, and leptin in the mammary fat pad of adult female rats.

Adipocytes from white adipose tissue secrete cytokines and other bioactive proteins which are collectively termed adipokines. Adiposity has been linked with increased breast cancer risk as adipokines secreted by adipocytes significantly affect epithelial cells from which breast cancer arises. Measurement of extracellular adipokine concentrations that would be involved in signaling through mammary tissue is therefore of importance.

Microdialysis sampling techniques applied to studies of the foreign body reaction.

Implanted materials including drug delivery devices and chemical sensors undergo what is termed the foreign body reaction (FBR). Depending on the device and its intended application, the FBR can have differing consequences. An extensive scientific research effort has been devoted to elucidating the cellular and molecular mechanisms that drive the FBR.

Comparison of microdialysis sampling perfusion fluid components on the foreign body reaction in rat subcutaneous tissue.

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration.

In vivo microdialysis sampling of cytokines from rat hippocampus: comparison of cannula implantation procedures.

Cytokines are signaling proteins that have been of significant importance in the field of immunology, since these proteins affect different cells in the immune system. In addition to their immune system significance, these proteins have recently been referred to as a third chemical communication network within the CNS. The role that cytokines play in orchestrating the immune response within tissues after a mechanical injury leads to potential complications if the source of cytokines (i.

Modulation of the foreign body reaction for implants in the subcutaneous space: microdialysis probes as localized drug delivery/sampling devices.

Modulation of the foreign body reaction is considered to be an important step toward creation of implanted sensors with reliable long-term performance. In this work, microdialysis probes were implanted into the subcutaneous space of Sprague-Dawley rats. The probe performance was evaluated by comparing collected endogenous glucose concentrations with internal standard calibration (2-deoxyglucose, antipyrine, and vitamin B12).

Antibody-enhanced microdialysis collection of CCL2 from rat brain.

Chemokine(C-C motif) Ligand 2 (CCL2 or MCP-1) is a signaling protein that is released under various conditions. In this study we demonstrate the first microdialysis collection of CCL2 from rat brain tissue using antibody-enhanced microdialysis. A monoclonal antibody to CCL2 was included in the dialysis perfusion fluid as an affinity agent to enhance the recovery of CCL2 both in vitro and in vivo.

In vitro and in vivo affinity microdialysis sampling of cytokines using heparin-immobilized microspheres.

Heparin-immobilized microspheres were included in microdialysis sampling perfusion fluids under both in vitro and in vivo conditions to improve the recovery of different cytokines, acidic fibroblast growth factor, vascular endothelial growth factor, monocyte chemoattractant protein-1 (or CCL2), and regulation upon activation normal T cell express sequence (or CCL5). Different strategies to dissociate captured CCL2 and CCL5 from the immobilized heparin were attempted, and both cytokines could be quantitatively eluted from the beads using a phosphate buffer (pH 7.4) containing 25% (v/v) acetonitrile which did not interfere with the subsequent detection of cytokine using an ELISA assay.

Heparin-immobilized microspheres for the capture of cytokines.

The preparation and characterization of heparin-immobilized microspheres which were used to bind acidic fibroblast growth factor (aFGF), vascular endothelial growth factor (VEGF), monocyte chemoattractant protein 1 (MCP-1/CCL2), and regulation upon activation normal T cell express sequence (RANTES/CCL5) is described. These beads were used as trapping agents in microdialysis sampling experiments in a separate study. Both free heparin and a synthesized heparin-albumin conjugate were immobilized onto microspheres and compared for their effectiveness.

Long-term subcutaneous microdialysis sampling and qRT-PCR of MCP-1, IL-6 and IL-10 in freely-moving rats.

Cytokines are important mediators of the wound healing response. However, sampling of cytokines from the interstitial fluid at a healing wound site in experimental animals is a challenge. Microdialysis sampling is an in vivo collection option for this purpose as it permits continuous sampling, while remaining contiguous with the wound microenvironment.

Long-term calibration considerations during subcutaneous microdialysis sampling in mobile rats.

The level at which implanted sensors and sampling devices maintain their calibration is an important research area. In this work, microdialysis probes with identical geometry and different membranes, polycarbonate/polyether (PC) or polyethersulfone (PES), were used with internal standards (Vitamin B(12) (MW 1355), antipyrine (MW 188) and 2-deoxyglucose (2-DG, MW 164)) and endogenous glucose to investigate changes in their long-term calibration after implantation into the subcutaneous space of Sprague-Dawley rats. Histological analysis confirmed an inflammatory response to the microdialysis probes and the presence of a collagen capsule.

How minimally invasive is microdialysis sampling? A cautionary note for cytokine collection in human skin and other clinical studies.

It is common to refer to microdialysis as a minimally invasive procedure, likening it to insertion of an artificial capillary. While a comparison of this type allows the process to be easily visualized by those outside the field, it tends to provide a false impression of the localized perturbation of the tissue space that is caused by catheter insertion. With the increased acceptance of microdialysis sampling as a viable in vivo sampling method, many researchers have begun to use the technique to explore inflammatory and immune-mediated diseases in the skin and other organs.

Detection of in vivo matrix metalloproteinase activity using microdialysis sampling and liquid chromatography/mass spectrometry.

Matrix metalloproteinases (MMPs) are a family of endoproteases that break down extracellular matrix and whose upregulation contributes to several diseases. A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed to quantify MMP-1 and MMP-9 substrates and their N-terminal peptide products in samples obtained from implanted microdialysis sampling probes. In vitro studies with purified human MMP-1 and MMP-9 were used to optimize the assay and determine the effectiveness of the local delivery of a broad-spectrum MMP inhibitor, GM 6001.

Affinity-based microdialysis sampling using heparin for in vitro collection of human cytokines.

Microdialysis sampling is a widely used method to sample from complex biological matrices. Cytokines are important signaling proteins that are typically recovered with low relative recovery values during microdialysis sampling. Heparin was included in the microdialysis perfusion fluid as an affinity agent to increase in vitro recovery of different cytokines through polyethersulfone (PES) microdialysis membranes with 100 kDa molecular weight cutoff.