The high incidence of degenerative tears and prevalence of retears (20-95%) after surgical repair makes rotator cuff injuries a significant health problem. This high retear rate is attributed to the failure of the repaired tissue to regenerate the native tendon-to-bone insertion (enthesis). Biological augmentation of surgical repair such as autografts, allografts, and xenografts are confounded by donor site morbidity, immunogenicity, and disease transmission, respectively. In contrast, these risks may be alleviated via growth factor therapy, which can actively influence the healing environment to promote functional repair. Several challenges have to be overcome before growth factor delivery can translate into clinical practice such as the selection of optimal growth factor(s) or combination, identification of the most efficient stage and duration of delivery, and the design considerations for the delivery device. Emerging insight into the injury-repair microenvironment and our understanding of growth factor mechanisms in healing are informing the design of advanced delivery scaffolds to effectively treat rotator cuff tears. Here, we review potential growth factor candidates, design parameters and material selection for growth factor delivery, innovative and dynamic delivery scaffolds, and novel therapeutic targets from tendon and developmental biology for the structural and functional healing of rotator cuff repair.

Electrolytic spray deposition was used to pattern surfaces with 2D metallic nanostructures. Spots that contain silver nanoparticles (AgNP) were created by landing solvated silver ions at desired locations using electrically floated masks to focus the metal ions to an area as little as 20 μm in diameter. The AgNPs formed are unprotected and their aggregates can be used for surface-enhanced Raman spectroscopy (SERS). The morphology and SERS activity of the NP structures were controlled by the surface coverage of landed silver ions. The NP structures created could be used as substrates onto which SERS samples were deposited or prepared directly on top of predeposited samples of interest. The evenly distributed hot spots in the micron-sized aggregates had an average SERS enhancement factor of 10(8) . The surfaces showed SERS activity when using lasers of different wavelengths (532, 633, and 785 nm) and were stable in air.

Whereas synthetic biodegradable polymers have been successfully applied for the delivery of biologics in other tissues, the anatomical complexity, poor blood supply, and reduced clearance of degradation byproducts in the rotator cuff create unique design challenges for implantable biomaterials. Here, we investigated lower molecular weight poly‐lactic acid co—epsilon‐caprolactone (PLA‐CL) formulations with varying molecular weight and film casting concentrations as potential matrices for the therapeutic delivery of biologics in the rotator cuff. Matrices were fabricated with target footprint dimensions to facilitate controlled and protected release of model biologic (Bovine Serum Albumin), and anatomically‐unhindered implantation under the acromion in a rodent model of acute rotator cuff repair. The matrix obtained from the highest polymeric‐film casting concentration showed a controlled release of model biologics payload. The tested matrices rapidly degraded during the initial 4 weeks due to preferential hydrolysis of the lactide‐rich regions within the polymer, and subsequently maintained a stable molecular weight due to the emergence of highly‐crystalline caprolactone‐rich regions. pH evaluation in the interior of the matrix showed minimal change signifying lesser accumulation of acidic degradation byproducts than seen in other bulk‐degrading polymers, and maintenance of conformational stability of the model biologic payload. The context‐dependent biocompatibility evaluation in a rodent model of acute rotator cuff repair showed matrix remodeling without eliciting excessive inflammatory reaction and is anticipated to completely degrade within 6 months. The engineered PLA‐CL matrices offer unique advantages in controlled and protected biologic delivery, non‐toxic biodegradation, and biocompatibility overcoming several limitations of commonly‐used biodegradable polyesters.

We describe a simple and inexpensive cellulose-derived and layer-by-layer stacked carbon fiber network electrode for capacitive deionization (CDI) of brackish water. The microstructure and chemical composition were characterized using spectroscopic and microscopic techniques; electrochemical/electrical performance was evaluated by cyclic voltammetry and 4-probe electrical conductivity and surface area by Brunauer-Emmett-Teller analysis, respectively. The desalination performance was investigated using a laboratory batch model CDI unit, under fixed applied voltage and varying salt concentrations. Electro-adsorption of NaCl on the graphite reinforced-cellulose (GrC) electrode reached equilibrium quickly (within 90 min) and the adsorbed salts were released swiftly (in 40 min) back into the solution, during reversal of applied potential. X-ray photoelectron spectroscopic studies clearly illustrate that sodium and chloride ions were physisorbed on the negative and positive electrodes, respectively during electro-adsorption. This GrC electrode showed an electro-adsorption capacity of 13.1 mg/g of the electrode at a cell potential of 1.2 V, with excellent recyclability and complete regeneration. The electrode has a high tendency for removal of specific anions, such as fluoride, nitrate, chloride, and sulfate from water in the following order: Cl->NO3->F->SO4(2-). GrC electrodes also showed resistance to biofouling with negligible biofilm formation even after 5 days of incubation in Pseudomonas putida bacterial culture. Our unique cost-effective methodology of layer-by-layer stacking of carbon nanofibers and concurrent reinforcement using graphite provides uniform conductivity throughout the electrode with fast electro-adsorption, rapid desorption, and extended reuse, making the electrode affordable for capacitive desalination of brackish water.

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Electrolytic spray deposition was used to pattern surfaces with 2D metallic nanostructures. Spots that contain silver nanoparticles (AgNP) were created by landing solvated silver ions at desired locations using electrically floated masks to focus the metal ions to an area as little as 20 mm in diameter. The AgNPs formed are unprotected and their aggregates can be used for surface-enhanced Raman spectroscopy (SERS). The morphology and SERS activity of the NP structures were controlled by the surface coverage of landed silver ions. The NP structures created could be used as substrates onto which SERS samples were deposited or prepared directly on top of predeposited samples of interest. The evenly distributed hot spots in the micron-sized aggregates had an average SERS enhancement factor of 10 8 . The surfaces showed SERS activity when using lasers of different wavelengths (532, 633, and 785 nm) and were stable in air.Metallic nanoparticles have attractive properties in catalysis, photonics, and chemical sensing. [1] Raman spectroscopy is a powerful nondestructive technique, [2] the sensitivity of which can be significantly improved through surfaceenhanced or tip-enhanced methods. [3] The enhancement arises from the proximity of the analytes to intense localized fields created by nanoscale objects. [4] The capability to modify, coat, and pattern surfaces with nanostructures is important for SERS and also for a wider range of nanomaterials applications. [5] Conventionally, modified surfaces are constructed by delivering intact nanoparticles to target locations through dropcasting or spin coating. [6] However, the difficulty in positioning discrete particles with control over orientation, position, and degree of aggregation means that drop casting of nanoparticles has not been widely used in the highthroughput preparation of SERS substrates. Immobilized and shell-isolated nanosystems [5b, 6c, 7] address these issues, but the necessary vacuum preparation procedures significantly increase the complexity of such approaches.Ion/surface collisions including ion soft-landing have been used to fabricate surface structures under vacuum. [8] Recently an electrolytic spray ionization method [9] has been developed that is capable of generating noble metal ions directly from their solids under ambient conditions as precursors for nanoparticle synthesis. Herein, we report the in situ fabrication of SERS-active spots and micro-scale patterns by landing ionized silver at desired locations where spontaneous cathodic reduction takes place, allowing the creation of nanostructure assemblies.Silver is a widely used SERS material [10] and the plasmon resonance of silver nanostructures is tunable through the visible to mid-infrared regions of the electromagnetic spectrum. [11] Electrolytic spray deposition readily creates spots of approximately 3 mm in diameter composed of silver particles (AgNP) at desired locations, both on top of previously deposited analyte as well as prior to analyte deposition (Figure 1). Both the NP-on-top and ...

Nanosurface engineering of metallic substrates for improved cellular response is a persistent theme in biomaterials research. The need to improve the long term prognosis of commercially available stents has led us to adopt a 'polymer-free' approach which is cost effective and industrially scalable. In this study, 316L stainless steel substrates were surface modified by hydrothermal treatment in alkaline pH, with and without the addition of a chromium precursor, to generate a well adherent uniform nanotopography. The modified surfaces showed improved hemocompatibility and augmented endothelialization, while hindering the proliferation of smooth muscle cells. Moreover, they also exhibited superior material properties like corrosion resistance, surface integrity and reduced metal ion leaching. The combination of improved corrosion resistance and selective vascular cell viability provided by nanomodification can be successfully utilized to offer a cell-friendly solution to the inherent limitations pertinent to bare metallic stents.

Tears in the rotator cuff are challenging to repair because of the complex, hypocellular, hypovascular, and movement‐active nature of the tendon and its enthesis. Insulin‐like Growth Factor‐1 (IGF‐1) is a promising therapeutic for this repair. However, its unstable nature, short half‐life, and ability to disrupt homeostasis has limited its clinical translation. Pegylation has been shown to improve the stability and sustain IGF‐1 levels in the systemic circulation without disrupting homeostasis. To provide localized delivery of IGF‐1 in the repaired tendons, we encapsulated pegylated IGF‐1 mimic and its controls (unpegylated IGF‐1 mimic and recombinant human IGF‐1) in polycaprolactone‐based matrices and evaluated them in a pre‐clinical rodent model of rotator cuff repair. Pegylated‐IGF‐1 mimic delivery reestablished the characteristic tendon‐to‐bone enthesis structure and improved tendon tensile properties within 8 weeks of repair compared to controls, signifying the importance of pegylation in this complex tissue regeneration. These results demonstrate a simple and scalable biologic delivery technology alternative to tissue‐derived grafts for soft tissue repair.