Assessment of Silver Levels in a Closed-Incision Negative Pressure Therapy Dressing: and Study.

In recent years, reticulated open-cell foam-based closed-incision negative pressure therapy (ROCF-ciNPT) has shown effectiveness in management of various postoperative incisions. These dressings consist of a skin interface layer that absorbs fluid from the skin surface and reduces the potential for microbial colonization within the dressing by means of ionic silver. This study examines the ability of silver to reduce the bioburden within the dressing as well as the localized effect due to potential silver mobility.

Light-inducible activation of cell cycle progression in Xenopus egg extracts under microfluidic confinement.

Cell-free Xenopus egg extract is a widely used and biochemically tractable model system that allows recapitulation and elucidation of fundamental cellular processes. Recently, the introduction of microfluidic extract manipulation has enabled compartmentalization of bulk extract and a newfound ability to study organelles on length scales that recapitulate key features of cellular morphology. While the microfluidic confinement of extracts has produced a compelling platform for the in vitro study of cell processes at physiologically-relevant length scales, it also imposes experimental limitations by restricting dynamic control over extract properties.

Immunofunctional photodegradable poly(ethylene glycol) hydrogel surfaces for the capture and release of rare cells.

Circulating tumor cells (CTCs) play a central role in cancer metastasis and represent a rich source of data for cancer prognostics and therapeutic guidance. Reliable CTC recovery from whole blood therefore promises a less invasive and more sensitive approach to cancer diagnosis and progression tracking. CTCs, however, are exceedingly rare in whole blood, making their quantitative recovery challenging.

Fabrication of Functional Biomaterial Microstructures by in Situ Photopolymerization and Photodegradation.

The in situ fabrication of poly(ethylene glycol) diacrylate (PEGDA) hydrogel microstructures within poly(dimethylsiloxane) (PDMS)-based microfluidic networks is a versatile technique that has enabled unique applications in biosensing, medical diagnostics, and the fundamental life sciences. Hydrogel structures have previously been patterned by the lithographic photopolymerization of PEGDA hydrogel forming solutions, a process that is confounded by oxygen-permeable PDMS. Here, we introduce an alternate PEG patterning technique that relies upon the optical sculpting of features by patterned light-induced erosion of photodegradable PEGDA deemed negative projection lithography.

Fast, irreversible modification of cysteines through strain releasing conjugate additions of cyclopropenyl ketones.

A method of cysteine alkylation using cyclopropenyl ketones is described. Due to the significant release of cyclopropene strain energy, reactions of thiols with cyclopropenyl ketones are both fast and irreversible and give rise to stable conjugate addition adducts. The resulting cyclopropenyl ketones have a low molecular weight and allow for simple attachment of amides via N-hydroxysuccinimide (NHS)-esters.

Controlling the Release of Small, Bioactive Proteins via Dual Mechanisms with Therapeutic Potential.

Injectable delivery systems that respond to biologically relevant stimuli present an attractive strategy for tailorable drug release. Here, the design and synthesis of unique polymers are reported for the creation of hydrogels that are formed in situ and degrade in response to clinically relevant endogenous and exogenous stimuli, specifically reducing microenvironments and externally applied light. Hydrogels are formed with polyethylene glycol and heparin-based polymers using a Michael-type addition reaction.

Tuning and Predicting Mesh Size and Protein Release from Step Growth Hydrogels.

Hydrogel-based depots are of growing interest for release of biopharmaceuticals; however, a priori selection of hydrogel compositions that will retain proteins of interest and provide desired release profiles remains elusive. Toward addressing this, in this work, we have established a new tool for the facile assessment of protein release from hydrogels and applied it to evaluate the effectiveness of mesh size estimations on predicting protein retention or release. Poly(ethylene glycol) (PEG)-based hydrogel depots were formed by photoinitiated step growth polymerization of four-arm PEG functionalized with norbornene (PEG-norbornene, 4% w/w to 20% w/w, M ∼ 5 to 20 kDa) and different dithiol cross-linkers (PEG M ∼ 1.

Biomaterials for 4D stem cell culture.

Stem cells reside in complex three-dimensional (3D) environments within the body that change with time, promoting various cellular functions and processes such as migration and differentiation. These complex changes in the surrounding environment dictate cell fate yet, until recently, have been challenging to mimic within cell culture systems. Hydrogel-based biomaterials are well suited to mimic aspects of these environments, owing to their high water content, soft tissue-like elasticity, and often-tunable biochemical content.

Aortic adventitial fibroblast sensitivity to mitogen activated protein kinase inhibitors depends on substrate stiffness.

Adventitial fibroblasts (AFs) are key determinants of arterial function and critical mediators of arterial disease progression. The effects of altered stiffness, particularly those observed across individuals during normal vascular function, and the mechanisms by which AFs respond to altered stiffness, are not well understood. To study the effects of matrix stiffness on AF phenotype, cytokine production, and the regulatory pathways utilized to interpret basic cell-matrix interactions, human aortic AFs were grown in 5%, 7.

Thiol-ene click hydrogels for therapeutic delivery.

Hydrogels are of growing interest for the delivery of therapeutics to specific sites in the body. For use as a delivery vehicle, hydrophilic precursors are usually laden with bioactive moieties and then directly injected to the site of interest for gel formation and controlled release dictated by precursor design. Hydrogels formed by thiol-ene click reactions are attractive for local controlled release of therapeutics owing to their rapid reaction rate and efficiency under mild aqueous conditions, enabling formation of gels with tunable properties often responsive to environmental cues.

Design of Thiol- and Light-sensitive Degradable Hydrogels using Michael-type Addition Reactions.

Injectable depots that respond to exogenous and endogenous stimuli present an attractive strategy for tunable, patient-specific drug delivery. Here, the design of injectable and multimodal degradable hydrogels that respond to externally applied light and physiological stimuli, specifically aqueous and reducing microenvironments, is reported. Rapid hydrogel formation was achieved using a thiol-maleimide click reaction between multifunctional poly(ethylene glycol) macromers.

Decreasing matrix modulus of PEG hydrogels induces a vascular phenotype in human cord blood stem cells.

Adult and congenital cardiovascular diseases are significant health problems that are often managed using surgery. Bypass grafting is a principal therapy, but grafts fail at high rates due to hyperplasia, fibrosis, and atherosclerosis. Biocompatible, cellularized materials that attenuate these complications and encourage healthy microvascularization could reduce graft failure, but an improved understanding of biomaterial effects on human stem cells is needed to reach clinical utility.

Designing degradable hydrogels for orthogonal control of cell microenvironments.

Degradable and cell-compatible hydrogels can be designed to mimic the physical and biochemical characteristics of native extracellular matrices and provide tunability of degradation rates and related properties under physiological conditions. Hence, such hydrogels are finding widespread application in many bioengineering fields, including controlled bioactive molecule delivery, cell encapsulation for controlled three-dimensional culture, and tissue engineering. Cellular processes, such as adhesion, proliferation, spreading, migration, and differentiation, can be controlled within degradable, cell-compatible hydrogels with temporal tuning of biochemical or biophysical cues, such as growth factor presentation or hydrogel stiffness.

Polyelectrolyte multilayer nanoshells with hydrophobic nanodomains for delivery of Paclitaxel.

Efficient and effective delivery of poorly water-soluble drug molecules, which constitute a large part of commercially available drugs, is a major challenge in the field of drug delivery. Several drugs including paclitaxel (PTX) which are used for cancer treatment are hydrophobic, exhibit poor aqueous solubility and need to be delivered using an appropriate carrier. In the present work, we engineered PTX-loaded polyelectrolyte films and microcapsules by pre-complexing PTX with chemically modified derivative of hyaluronic acid (alkylamino hydrazide) containing hydrophobic nanocavities, and subsequent assembly with either poly(l-lysine) (PLL) or quaternized chitosan (QCHI) as polycations.