Imaging of adeno-associated viral capsids for purposes of gene editing using CEST NMR/MRI.

PURPOSE: Gene therapy using adeno-associated virus (AAV) vector-mediated gene delivery has undergone substantial growth in recent years with promising results in both preclinical and clinical studies, as well as emerging regulatory approval. However, the inability to quantify the efficacy of gene therapy from cellular delivery of gene-editing technology to specific functional outcomes is an obstacle for efficient development of gene therapy treatments. Building on prior works that used the CEST reporter gene lysine rich protein, we hypothesized that AAV viral capsids may generate endogenous CEST contrast from an abundance of surface lysine residues. METHODS: NMR experiments were performed on isolated solutions of AAV serotypes 1-9 on a Bruker 800-MHz vertical scanner. In vitro experiments were performed for testing of CEST-NMR contrast of AAV2 capsids under varying pH, density, biological transduction stage, and across multiple serotypes and mixed biological media. Reverse transcriptase-polymerase chain reaction was used to quantify virus concentration. Subsequent experiments at 7 T optimized CEST saturation schemes for AAV contrast detection and detected AAV2 particles encapsulated in a biocompatible hydrogel administered in the hind limb of mice. RESULTS: CEST-NMR experiments revealed CEST contrast up to 52% for AAV2 viral capsids between 0.6 and 0.8 ppm. CEST contrast generated by AAV2 demonstrated high levels of CEST contrast across a variety of chemical environments, concentrations, and saturation schemes. AAV2 CEST contrast displayed significant positive correlations with capsid density (R2 > 0.99, p < 0.001), pH (R2 = 0.97, p = 0.01), and viral titer per cell count (R2 = 0.92, p < 0.001). Transition to a preclinical field strength yielded up to 11.8% CEST contrast following optimization of saturation parameters. In vivo detection revealed statistically significant molecular contrast between viral and empty hydrogels using both mean values (4.67 ± 0.75% AAV2 vs. 3.47 ± 0.87% empty hydrogel, p = 0.02) and quantile analysis. CONCLUSION: AAV2 viral capsids exhibit strong capacity as an endogenous CEST contrast agent and can potentially be used for monitoring and evaluation of AAV vector-mediated gene therapy protocols.

Sustained Exosome-Guided Macrophage Polarization Using Hydrolytically Degradable PEG Hydrogels for Cutaneous Wound Healing: Identification of Key Proteins and MiRNAs, and Sustained Release Formulation.

Macrophages (Mφs) are characterized by remarkable plasticity, an essential component of chronic inflammation. Thus, an appropriate and timely transition from proinflammatory (M1) to anti-inflammatory (M2) Mφs during wound healing is vital to promoting resolution of acute inflammation and enhancing tissue repair. Herein, exosomes derived from M2-Mφs (M2-Exos), which contain putative key regulators driving Mφ polarization, are used as local microenvironmental cues to induce reprogramming of M1-Mφs toward M2-Mφs for effective wound management. As an injectable controlled release depot for exosomes, hydrolytically degradable poly(ethylene glycol) (PEG) hydrogels (Exogels) are designed and employed for encapsulating M2-Exos to maximize their therapeutic effects in cutaneous wound healing. The degradation time of the hydrogels is adjustable from 6 days or up to 27 days by controlling the crosslinking density and tightness. The localization of M2-Exos leads to a successful local transition from M1-Mφs to M2-Mφs within the lesion for more than 6 days, followed by enhanced therapeutic effects including rapid wound closure and increased healing quality in an animal model for cutaneous wound healing. Collectively, the hydrolytically degradable PEG hydrogel-based exosome delivery system may serve as a potential tool in regulating local polarization state of Mφs, which is crucial for tissue homeostasis and wound repair.

Surface Force Measurements of Mussel-Inspired Pressure-Sensitive Adhesives.

Translating fundamental studies of marine mussel adhesion into practical mussel-inspired wet adhesives remains an important technological challenge. To adhere, mussels secrete adhesive proteins rich in the catecholic amino acid 3,4-dihydroxyphenylalanine (Dopa) and positively charged lysine. Consequently, numerous synthetic adhesives incorporating catecholic and cationic functionalities have been designed. However, despite widespread research, uncertainties remain about the optimal design of synthetic mussel-inspired adhesives. Here, we present a study of the adhesion of mussel-inspired pressure-sensitive adhesives. We explore the effects of catechol content, molecular architecture, and solvent quality on pressure-sensitive adhesive (PSA) adhesion and cohesion measured in a surface forces apparatus. Our findings demonstrate that the influence of catechol content depends on the choice of solvent and that adhesive performance is dictated by film composition rather than molecular architecture. Our results also highlight the importance of electrostatic and hydrophobic interactions for adhesion and cohesion in aqueous environments. Together, our findings contribute to an improved understanding of the interplay between materials chemistry, environmental conditions, and adhesive performance to facilitate the design of bioinspired wet adhesives.

In vivo Sealing of Fetoscopy-Induced Fetal Membrane Defects by Mussel Glue.

INTRODUCTION: The benefits of fetal surgery are impaired by the high incidence of iatrogenic preterm prelabor rupture of the fetal membranes (iPPROM), for which chorioamniotic separation has been suggested as a potential initiator. Despite the urgent need to prevent iPPROM by sealing the fetoscopic puncture site after intervention, no approach has been clinically translated. METHODS: A mussel-inspired biomimetic glue was tested in an ovine fetal membrane (FM) defect model. The gelation time of mussel glue (MG) was first optimized to make it technically compatible with fetal surgery. Then, the biomaterial was loaded in polytetrafluoroethylene-coated nitinol umbrella-shaped receptors and applied on ovine FM defects (N = 10) created with a 10 French trocar. Its sealing performance and tissue response were analyzed 10 days after implantation by amniotic fluid (AF) leakage and histological methods. RESULTS: All ewes and fetuses recovered well after the surgery, and 100% ewe survival and 91% fetal survival were observed at explantation. All implants were tight at explantation, and no AF leakage was observed in any of them. Histological analysis revealed a mild tissue response to the implanted glue. CONCLUSION: MG showed promising properties for the sealing of FM defects and thereby the prevention of preterm birth. Studies to analyze the long-term tissue response to the sealant should be performed.

Phenolic-enabled nanotechnology: versatile particle engineering for biomedicine.

Phenolics are ubiquitous in nature and have gained immense research attention because of their unique physiochemical properties and widespread industrial use. In recent decades, their accessibility, versatile reactivity, and relative biocompatibility have catalysed research in phenolic-enabled nanotechnology (PEN) particularly for biomedical applications which have been a major benefactor of this emergence, as largely demonstrated by polydopamine and polyphenols. Therefore, it is imperative to overveiw the fundamental mechanisms and synthetic strategies of PEN for state-of-the-art biomedical applications and provide a timely and comprehensive summary. In this review, we will focus on the principles and strategies involved in PEN and summarize the use of the PEN synthetic toolkit for particle engineering and the bottom-up synthesis of nanohybrid materials. Specifically, we will discuss the attractive forces between phenolics and complementary structural motifs in confined particle systems to synthesize high-quality products with controllable size, shape, composition, as well as surface chemistry and function. Additionally, phenolic's numerous applications in biosensing, bioimaging, and disease treatment will be highlighted. This review aims to provide guidelines for new scientists in the field and serve as an up-to-date compilation of what has been achieved in this area, while offering expert perspectives on PEN's use in translational research.

A Modular Strategy for Functional Pressure Sensitive Adhesives.

A modular approach to synthesizing functional pressure sensitive adhesives (PSAs) was introduced, wherein a modifiable acrylic PSA copolymer was synthesized by copolymerizing common PSA monomers with 6 mol % glycidyl methacrylate, allowing for subsequent functional group modification via the pendant epoxide functionality. This postmodification technique has the advantage of allowing the installation of a variety of functional groups relevant to adhesion, without variation of molecular weight. Because comparisons of cohesive and adhesive performance of candidate PSAs can be complicated by molecular weight differences, this strategy simplifies direct comparisons of the effects of functional groups on performance. As a proof of concept, a mussel-inspired catecholic PSA was synthesized by postreaction of the epoxide scaffold polymer with a thiol-modified catechol, allowing the effect of catechol on underlying structure-property relationships to be determined without variation in molecular weight. The mechanical performance of catecholic PSA was compared to relevant control PSAs by using industry-standard 180° peel and static shear tests, revealing an increase in peel strength achieved through catechol modification. Moreover, we observed an unexpected enhancement in PSA cohesive strength attributed to oxidation of catechol, which cannot be attributed to differences in molecular weight, a common source of changes in PSA cohesive strength.

Interfacial Assembly Inspired by Marine Mussels and Antifouling Effects of Polypeptoids: A Neutron Reflection Study.

Polypeptoid-coated surfaces and many surface-grafted hydrophilic polymer brushes have been proven efficient in antifouling-the prevention of nonspecific biomolecular adsorption and cell attachment. Protein adsorption, in particular, is known to mediate subsequent cell-surface interactions. However, the detailed antifouling mechanism of polypeptoid and other polymer brush coatings at the molecular level is not well understood. Moreover, most adsorption studies focus only on measuring a single adsorbed mass value, and few techniques are capable of characterizing the hydrated in situ layer structure of either the antifouling coating or adsorbed proteins. In this study, interfacial assembly of polypeptoid brushes with different chain lengths has been investigated in situ using neutron reflection (NR). Consistent with past simulation results, NR revealed a common two-step structure for grafted polypeptoids consisting of a dense inner region that included a mussel adhesive-inspired oligopeptide for grafting polypeptoid chains and a highly hydrated upper region with very low polymer density (molecular brush). Protein adsorption was studied with human serum albumin (HSA) and fibrinogen (FIB), two common serum proteins of different sizes but similar isoelectric points (IEPs). In contrast to controls, we observed higher resistance by grafted polypeptoid against adsorption of the larger FIB, especially for longer chain lengths. Changing the pH to close to the IEPs of the proteins, which generally promotes adsorption, also did not significantly affect the antifouling effect against FIB, which was corroborated by atomic force microscopy imaging. Moreover, NR enabled characterization of the in situ hydrated layer structures of the polypeptoids together with proteins adsorbed under selected conditions. While adsorption on bare SiO2 controls resulted in surface-induced protein denaturation, this was not observed on polypeptoids. Our current results therefore highlight the detailed in situ view that NR may provide for characterizing protein adsorption on polymer brushes as well as the excellent antifouling behavior of polypeptoids.

Molecular design principles of Lysine-DOPA wet adhesion.

The mussel byssus has long been a source of inspiration for the adhesion community. Recently, adhesive synergy between flanking lysine (Lys, K) and 3,4-Dihydroxyphenylalanine (DOPA, Y) residues in the mussel foot proteins (Mfps) has been highlighted. However, the complex topological relationship of DOPA and Lys as well as the interfacial adhesive roles of other amino acids have been understudied. Herein, we study adhesion of Lys and DOPA-containing peptides to organic and inorganic substrates using single-molecule force spectroscopy (SMFS). We show that a modest increase in peptide length, from KY to (KY)3, increases adhesion strength to TiO2. Surprisingly, further increase in peptide length offers no additional benefit. Additionally, comparison of adhesion of dipeptides containing Lys and either DOPA (KY) or phenylalanine (KF) shows that DOPA is stronger and more versatile. We furthermore demonstrate that incorporating a nonadhesive spacer between (KY) repeats can mimic the hidden length in the Mfp and act as an effective strategy to dissipate energy.

Cooperativity of Catechols and Amines in High-Performance Dry/Wet Adhesives.

The outstanding adhesive performance of mussel byssal threads has inspired materials scientists over the past few decades. Exploiting the amino-catechol synergy, polymeric pressure-sensitive adhesives (PSAs) have now been synthesized by copolymerizing traditional PSA monomers, butyl acrylate and acrylic acid, with mussel-inspired lysine- and aromatic-rich monomers. The consequences of decoupling amino and catechol moieties from each other were compared (that is, incorporated as separate monomers) against a monomer architecture in which the catechol and amine were coupled together in a fixed orientation in the monomer side chain. Adhesion assays were used to probe performance at the molecular, microscopic, and macroscopic levels by a combination of AFM-assisted force spectroscopy, peel and static shear adhesion. Coupling of catechols and amines in the same monomer side chain produced optimal cooperative effects in improving the macroscopic adhesion performance.

Enhanced Adhesion and Cohesion of Bioinspired Dry/Wet Pressure-Sensitive Adhesives.

The byssus-mediated adhesion of marine mussels is a widely mimicked system for robust adhesion in both dry and wet conditions. Mussel holdfasts are fabricated from proteins that contain a significant amount of the unique catecholic amino acid dihydroxyphenylalanine, which plays a key role in enhancing interfacial adhesion to organic and inorganic marine surfaces and contributes to cohesive strength of the holdfast. In this work, pressure-sensitive adhesives (PSAs) were synthesized by copolymerization of dopamine methacrylamide (DMA) with common PSA monomers, butyl acrylate and acrylic acid, with careful attention paid to the effects of catechol on adhesive and cohesive properties. A combination of microscopic and macroscopic adhesion assays was used to study the effect of catechol on adhesion performance of acrylic PSAs. Addition of only 5% DMA to a conventional PSA copolymer containing butyl acrylate and acrylic acid resulted in 6-fold and 2.5-fold increases in work required to separate the PSA from silica and polystyrene, respectively, and a large increase in 180° peel adhesion against stainless steel after 24 h storage in both ambient and underwater conditions. Moreover, the holding power of the catechol PSAs on both steel and high-density polyethylene under shear load continuously increased as a function of catechol concentration, up to a maximum of 10% DMA. We also observed stark increases in shear and peel adhesion for the catecholic adhesives over PSAs with noncatecholic aromatic motifs, further underlining the benefits of catechols in PSAs. Overall, catechol PSAs perform extremely well on polar and metallic surfaces. The advantage of incorporating catechols in PSA formulations, however, is less straightforward for peel adhesion in nonpolar, organic substrates and tackiness of the PSAs.

Biomaterials in fetal surgery.

Fetal surgery and fetal therapy involve surgical interventions on the fetus in utero to correct or ameliorate congenital abnormalities and give a developing fetus the best chance at a healthy life. Historical use of biomaterials in fetal surgery has been limited, and most biomaterials used in fetal surgeries today were originally developed for adult or pediatric patients. However, as the field of fetal surgery moves from open surgeries to minimally invasive procedures, many opportunities exist for innovative biomaterials engineers to create materials designed specifically for the unique challenges and opportunities of maternal-fetal surgery. Here, we review biomaterials currently used in clinical fetal surgery as well as promising biomaterials in development for eventual clinical translation. We also highlight unmet challenges in fetal surgery that could particularly benefit from novel biomaterials, including fetal membrane sealing and minimally invasive myelomeningocele defect repair. Finally, we conclude with a discussion of the underdeveloped fetal immune system and opportunities for exploitation with novel immunomodulating biomaterials.

Surface Functionalization and Patterning by Multifunctional Resorcinarenes.

Plant phenolic compounds and catecholamines have been widely used to obtain substrate-independent precursor nanocoatings and adhesives. Nevertheless, there are downsides in using such phenolic compounds for surface modification such as formation of nonuniform coatings, need for multistep modification, and restricted possibilities for postfunctionalization. In this study, inspired by a strong binding ability of natural polyphenols found in plants, we used three different macrocyclic polyphenols, known as resorcin[4]arenes, to modify the surface of different substrates by simple dip-coating into the dilute solution of these compounds. Eight hydroxyl groups on the large rim of these resorcin[4]arenes provide multiple anchoring points to the surface, whereas the lower rim decorated with different appending groups introduces the desired chemical and physical functionalities to the substrate's surface. Deposition of a uniform and transparent resorcinarene layer on the surface was confirmed by several surface characterization techniques. Incubation of the modified substrates in different environments indicated that the stability of the resorcinarene layer was dependent on the type of substrate and the pH value. The most stable resorcinarene layer was formed on amine-functionalized substrates. The surface was modified with alkenyl functional groups in one step using a resorcinarene compound possessing four alkenyl appending groups on its small rim. Thiol-ene photoclick chemistry was used to site-selectively postfunctionalize the surface with hydrophilic and hydrophobic micropatterns, which was confirmed by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Thus, we demonstrate that resorcin[4]arenes extend the scope of applications of plant polyphenol and mussel-inspired precursors to tailor-made multifunctional nanocoatings, suitable for a variety of potential applications in biotechnology, biology, and material science.

Facile synthesis and surface modification of bioinspired nanoparticles from quercetin for drug delivery.

Nanoparticle-mediated drug delivery has demonstrated great potential to treat various diseases especially cancer. However, there is an unmet need for the scalable synthesis of multifunctional nanoparticles to meet the complex challenges of drug delivery. Here we show that we can synthesize nanoparticles from the polyphenol quercetin, which can be conveniently functionalized with ligands and drug molecules by simple mixing under ambient conditions. Nanoparticles (∼30-40 nm in diameter) were formed by oxidative self-polymerization of quercetin in alkaline buffer (pH 9). The reactivity of oxidized polyphenols was exploited to immobilize amine-terminated methoxy poly(ethylene glycol) on the nanoparticles' surface for steric stability, followed by loading with doxorubicin as a model drug. Surface modification of the nanoparticles was confirmed by X-ray Photoelectron Spectroscopy. An antioxidant assay showed that the nanoparticles retained some antioxidant activity. The nanoparticles were readily internalized by KB cells via an endo-lysosomal pathway. Doxorubicin-loaded nanoparticles showed a drug loading of 35.6 ± 4.9% w/w with a loading efficiency of 88.9 ± 12.4%, sustained drug release, and potent cytotoxicity in vitro. Our findings demonstrate a promising new application for naturally occurring polyphenols as a renewable source of drug delivery nanocarriers that can be synthesized at low cost with minimal equipment.

Injectable dynamic covalent hydrogels of boronic acid polymers cross-linked by bioactive plant-derived polyphenols.

We report here the development of hydrogels formed at physiological conditions using PEG (polyethylene glycol) based polymers modified with boronic acids (BAs) as backbones and the plant derived polyphenols ellagic acid (EA), epigallocatechin gallate (EGCG), tannic acid (TA), nordihydroguaiaretic acid (NDGA), rutin trihydrate (RT), rosmarinic acid (RA) and carminic acid (CA) as linkers. Rheological frequency sweep and single molecule force spectroscopy (SMFS) experiments show that hydrogels linked with EGCG and TA are mechanically stiff, arising from the dynamic covalent bond formed by the polyphenol linker and boronic acid functionalized polymer. Stability tests of the hydrogels in physiological conditions revealed that gels linked with EA, EGCG, and TA are stable. We furthermore showed that EA- and EGCG-linked hydrogels can be formed via in situ gelation in pH 7.4 buffer, and provide long-term steady state release of bioactive EA. In vitro experiments showed that EA-linked hydrogel significantly reduced the viability of CAL-27 human oral cancer cells via gradual release of EA.

Polydopamine Surface Chemistry: A Decade of Discovery.

Polydopamine is one of the simplest and most versatile approaches to functionalizing material surfaces, having been inspired by the adhesive nature of catechols and amines in mussel adhesive proteins. Since its first report in 2007, a decade of studies on polydopamine molecular structure, deposition conditions, and physicochemical properties have ensued. During this time, potential uses of polydopamine coatings have expanded in many unforeseen directions, seemingly only limited by the creativity of researchers seeking simple solutions to manipulating surface chemistry. In this review, we describe the current state of the art in polydopamine coating methods, describe efforts underway to uncover and tailor the complex structure and chemical properties of polydopamine, and identify emerging trends and needs in polydopamine research, including the use of dopamine analogs, nitrogen-free polyphenolic precursors, and improvement of coating mechanical properties.

Exploratory Testing of Diatom Silica to Map the Role of Material Attributes on Cell Fate.

Porous silica is an attractive biomaterial in many applications, including drug-delivery systems, bone-graft fillers and medical devices. The issue with porous silica biomaterials is the rate at which they resorb and the significant role played by interfacial chemistry on the host response in vivo. This paper explores the potential of diatom-biosilica as a model tool to assist in the task of mapping and quantifying the role of surface topography and chemical cues on cell fate. Diatoms are unicellular microalgae whose cell walls are composed of, amorphous nanopatterned biosilica that cannot be replicated synthetically. Their unique nanotopography has the potential to improve understanding of interface reactions between materials and cells. This study used Cyclotella meneghiniana as a test subject to assess cytotoxicity and pro-inflammatory reactions to diatom-biosilica. The results suggest that diatom-biosilica is non-cytotoxic to J774.2 macrophage cells, and supports cell proliferation and growth. The addition of amine and thiol linkers have shown a significant effect on cytotoxicity, growth and cytokine response, thus warranting further investigation into the interfacial effects of small chemical modifications to substrate surfaces. The overall findings suggest diatom-biosilica offers a unique platform for in-depth investigation of the role played by nanotopography and chemistry in biomedical applications.

Size Control and Fluorescence Labeling of Polydopamine Melanin-Mimetic Nanoparticles for Intracellular Imaging.

As synthetic analogs of the natural pigment melanin, polydopamine nanoparticles (NPs) are under active investigation as non-toxic anticancer photothermal agents and as free radical scavenging therapeutics. By analogy to the widely adopted polydopamine coatings, polydopamine NPs offer the potential for facile aqueous synthesis and incorporation of (bio)functional groups under mild temperature and pH conditions. However, clear procedures for the convenient and reproducible control of critical NP properties such as particle diameter, surface charge, and loading with functional molecules have yet to be established. In this work, we have synthesized polydopamine-based melanin-mimetic nanoparticles (MMNPs) with finely controlled diameters spanning ≈25 to 120 nm and report on the pH-dependence of zeta potential, methodologies for PEGylation, and the incorporation of fluorescent organic molecules. A comprehensive suite of complementary techniques, including dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), X-ray photoelectron spectroscopy (XPS), zeta-potential, ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy, and confocal microscopy, was used to characterize the MMNPs and their properties. Our PEGylated MMNPs are highly stable in both phosphate-buffered saline (PBS) and in cell culture media and exhibit no cytotoxicity up to at least 100 µg mL-1 concentrations. We also show that a post-functionalization methodology for fluorophore loading is especially suitable for producing MMNPs with stable fluorescence and significantly narrower emission profiles than previous reports, suggesting they will be useful for multimodal cell imaging. Our results pave the way towards biomedical imaging and possibly drug delivery applications, as well as fundamental studies of MMNP size and surface chemistry dependent cellular interactions.

Deposition Kinetics of Bioinspired Phenolic Coatings on Titanium Surfaces.

Polyphenols can form functional coatings on a variety of different materials through auto-oxidative surface polymerization in a manner similar to polydopamine coatings. However, the mechanisms behind the coating deposition are poorly understood. We report the coating deposition kinetics of the polyphenol tannic acid (TA) and the simple phenolic compound pyrogallol (PG) on titanium surfaces. The coating deposition was followed in real time over a period of 24 h using a quartz crystal microbalance with dissipation monitoring (QCM-D). TA coatings revealed a multiphasic layer formation: the deposition of an initial rigid layer was followed by the buildup of an increasingly dissipative layer, before mass adsorption stopped after approximately 5 h of coating time. The PG deposition was biphasic, starting with the adsorption of a nonrigid viscoelastic layer which was followed by layer stiffening upon further mass adsorption. Coating evaluation by ellipsometry and AFM confirmed the deposition kinetics determined by QCM-D and revealed maximum coating thicknesses of approximately 50 and 75 nm for TA and PG, respectively. Chemical characterization of the coatings and polymerized polyphenol particles indicated the involvement of both physical and chemical interactions in the auto-oxidation reactions.

MUC1-Targeted Cancer Cell Photothermal Ablation Using Bioinspired Gold Nanorods.

Recent studies have highlighted the overexpression of mucin 1 (MUC1) in various epithelial carcinomas and its role in tumorigenesis. These mucins present a novel targeting opportunity for nanoparticle-mediated photothermal cancer treatments due to their unique antenna-like extracellular extension. In this study, MUC1 antibodies and albumin were immobilized onto the surface of gold nanorods using a "primer" of polydopamine (PD), a molecular mimic of catechol- and amine-rich mussel adhesive proteins. PD forms an adhesive platform for the deposition of albumin and MUC1 antibodies, achieving a surface that is stable, bioinert and biofunctional. Two-photon luminescence confocal and darkfield scattering imaging revealed targeting of MUC1-BSA-PD-NRs to MUC1+ MCF-7 breast cancer and SCC-15 squamous cell carcinoma cells lines. Treated cells were exposed to a laser encompassing the near-infrared AuNR longitudinal surface plasmon and assessed for photothermal ablation. MUC1-BSA-PD-NRs substantially decreased cell viability in photoirradiated MCF-7 cell lines vs. MUC1- MDA-MB-231 breast cancer cells (p < 0.005). Agents exhibited no cytotoxicity in the absence of photothermal treatment. The facile nature of the coating method, combined with targeting and photoablation efficacy, are attractive features of these candidate cancer nanotherapeutics.

Mussel-Inspired Modification of Nanofibers for REST siRNA Delivery: Understanding the Effects of Gene-Silencing and Substrate Topography on Human Mesenchymal Stem Cell Neuronal Commitment.

In this study, we promote neuronal differentiation of human mesenchymal stem cells (MSCs) through scaffold-mediated sustained release of siRNA targeting RE-1 silencing transcription factor (REST). Poly (ϵ-caprolactone) nanofibers were surface modified with mussel inspired DOPA-melanin (DM) coating for adsorption of REST siRNA. DM modification increased siRNA-loading efficiency and reduced the initial burst release. Fiber alignment and DM modification enhanced REST knockdown efficiencies. Under non-specific differentiation condition, REST silencing and fiber topography enhanced MSC neuronal markers expressions and reduced glial cell commitment. Such scaffolds may find useful applications in enhancing MSCs neuronal differentiation under non-specific conditions such as an in vivo environment.