Multifunctional 3D-Printed Wound Dressings.

Personalized wound dressings provide enhanced healing for different wound types; however multicomponent wound dressings with discretely controllable delivery of different biologically active agents are yet to be developed. Here we report 3D-printed multicomponent biocomposite hydrogel wound dressings that have been selectively loaded with small molecules, metal nanoparticles, and proteins for independently controlled release at the wound site. Hydrogel wound dressings carrying antibacterial silver nanoparticles and vascular endothelial growth factor with predetermined release profiles were utilized to study the physiological response of the wound in a mouse model. Compared to controls, the application of dressings resulted in improvement in granulation tissue formation and differential levels of vascular density, dependent on the release profile of the growth factor. Our study demonstrates the versatility of the 3D-printed hydrogel dressings that can yield varied physiological responses in vivo and can further be adapted for personalized treatment of various wound types.

Fluorescent Droplet Cytometry for On-Cell Phenotype Tracking.

Profiling the heterogeneous phenotypes of live cancer cells is a key capability that requires single-cell analysis. However, acquiring information at the single-cell level for live cancer cells is challenging when small collections of cells are being targeted. Here, we report single-cell analysis for low abundance cells enabled by fluorescent droplet cytometry (FDC), an approach that uses a biomarker-specific enzymatic fluorescent assay carried out using a droplet microfluidic platform. FDC utilizes DNA-functionalized antibodies in droplets to achieve specific on-cell target detection and enables characterization and profiling of live cancer cells with single-cell resolution based on their surface phenotype. Using this approach, we achieve live-cell phenotypic profiling of multiple surface markers acquired with small (<40 cells) collections of cells.

Curvature-Mediated Surface Accessibility Enables Ultrasensitive Electrochemical Human Methyltransferase Analysis.

The development of new tools for tracking the activity of human DNA methyltransferases is an important goal given the role of this enzyme as a cancer biomarker and epigenetic modulator. However, analysis of the human DNA (cytosine-5)-methyltransferase 1 (Dnmt1) activity is challenging, especially in crude samples, because of the low activity and large size of the enzyme. Here, we report a new approach to Dnmt analysis that combines nanostructured electrodes with a digest-and-amplify strategy that directly monitors Dnmt1 activity with high sensitivity. Nanostructured electrodes are required for the function of the assay to promote the accessibility of the electrode for human Dnmt1. Moreover, DNA-templated deposition of silver nanoparticles (for signal amplification) is combined with DNA Exonuclease I digestion to yield optimal target-to-control signals. We achieve high sensitivity for the detection of human Dnmt1, and particularly Dnmt1 from crude cell lysates. Specifically, the detection limit of our electrochemical assay is 20 pM, which is 2 orders of magnitude lower than previously reported methods. In crude lysates, we detected Dnmt1 from as few as five colorectal cancer cells (HCT116). With biopsy samples, we were able to distinguish colorectal tumor tissue from healthy adjacent tissue using only 10 µg of sample. The strategy enables analysis of an important marker underlying the epigenetic basis of cancerous transformation.