Folding molecular origami from ribosomal RNA.

Approximately 80 percent of the total RNA in cells is ribosomal RNA (rRNA), making it an abundant and inexpensive natural source of long, single-stranded nucleic acid, which could be used as raw material for the fabrication of molecular origami. In this study, we demonstrate efficient and robust construction of 2D and 3D origami nanostructures utilizing cellular rRNA as a scaffold and DNA oligonucleotide staples. We present calibrated protocols for the robust folding of contiguous shapes from one or two rRNA subunits that are efficient to allow folding using crude extracts of total RNA. We also show that RNA maintains stability within the folded structure. Lastly, we present a novel and comprehensive analysis and insights into the stability of RNA:DNA origami nanostructures and demonstrate their enhanced stability when coated with polylysine-polyethylene glycol in different temperatures, low Mg2+ concentrations, human serum, and in the presence of nucleases (DNase I or RNase H). Thus, laying the foundation for their potential implementation in emerging biomedical applications, where folding rRNA into stable structures outside and inside cells would be desired.

Skin microbiota dynamics following B. subtilis formulation challenge: an in vivo study in mice.

BACKGROUND: Modulating the microbiota is a leading-edge strategy for the restoration and maintenance of a healthy, balanced environment. The use of health-promoting bacteria has demonstrated some potential benefits as an alternative for skin microbiota intervention. Here, we investigate the manipulation of mice skin microbiota using B. subtilis incorporated into a supportive Pluronic F-127 hydrogel formulation. The formula plays an important role in delivering the bacteria to the desired action site. RESULTS: The B. subtilis challenge induced a shift in the composition and abundance of the skin microbiota. Containment of B. subtilis in the Pluronic F-127 hydrogel accelerated bacterial modulation compared with free B. subtilis. The abundance of both Staphylococcus and Corynebacterium spp. was altered as a result of the live bacterial intervention: the abundance of Corynebacterium increased while that of Staphylococcus decreased. Four days after last application of the B. subtilis formulation, B. subtilis counts returned to its initial level. CONCLUSIONS: B. subtilis intervention can induce a shift in the skin microbiota, influencing the abundance of commensal, beneficial, and pathogenic bacteria. Containment of B. subtilis in Pluronic hydrogel accelerates the microbial alteration, probably by facilitating bacterial attachment and supporting continuous growth. Our results reveal the ability of B. subtilis in Pluronic to modulate the skin microbiota composition, suggesting that the formulation holds therapeutic potential for skin disease treatment.

Local Toxicity of Topically Administrated Thermoresponsive Systems: In Vitro Studies with In Vivo Correlation.

Thermoresponsive materials have the ability to respond to a small change in temperature-a property that makes them useful in a wide range of applications and medical devices. Although very promising, there is only little conclusive data about the cytotoxicity and tissue toxicity of these materials. This work studied the biocompatibility of three Food and Drug Administration approved thermoresponsive polymers: poly( N-isopropyl acrylamide), poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) tri-block copolymer, and poly(lactic acid-co-glycolic acid) and poly(ethylene glycol) tri-block copolymer. Fibroblast NIH 3T3 and HaCaT keratinocyte cells were used for the cytotoxicity testing and a mouse model for the in vivo evaluation. In vivo results generally showed similar trends as the results seen in vitro, with all tested materials presenting a satisfactory biocompatibility in vivo. pNIPAM, however, showed the highest toxicity both in vitro and in vivo, which was explained by the release of harmful monomers and impurities. More data focusing on the biocompatibility of novel thermoresponsive biomaterials will facilitate the use of existing and future medical devices.

In Situ Dual Cross-Linking of Neat Biogel with Controlled Mechanical and Delivery Properties.

Injectable biomaterials play a critical role in many biomedical applications. These materials, however, often have limitations in mechanical and drug-eluting properties attributed to their high water content and the weak secondary forces holding them together. Here we describe a new injectable material based on two complementary water-free, prepolymers modified with succinimidyl carbonate (SC) or with NH2 end groups that form a stiff matrix upon mixing. Cross-linking involves an immediate reaction between PEG4-SC and PEG4-NH2 that forms carbamate bonds and a delayed reaction of PEG4-SC with hydroxyl functional groups that forms carbonate bonds. The mechanical properties, swelling, and erosion kinetics of this biomaterial can be fine-tuned by varying the ratio between the two prepolymers. Bovine serum albumin and poorly water-soluble free base doxorubicin were readily loaded into this system, resulting in a high drug loading content attributed to the absence of water in the formulation. Controlled release over a period of 1 to 30 days was observed, depending on mixture composition and drug properties. The injectable nature of the formulation, its tailored mechanical properties, the fact that it can be cross-linked by two separate mechanisms, and its ability to incorporate and release hydrophilic and hydrophobic drugs make it very attractive as a drug delivery system.

Near-infrared-actuated devices for remotely controlled drug delivery.

A reservoir that could be remotely triggered to release a drug would enable the patient or physician to achieve on-demand, reproducible, repeated, and tunable dosing. Such a device would allow precise adjustment of dosage to desired effect, with a consequent minimization of toxicity, and could obviate repeated drug administrations or device implantations, enhancing patient compliance. It should exhibit low off-state leakage to minimize basal effects, and tunable on-state release profiles that could be adjusted from pulsatile to sustained in real time. Despite the clear clinical need for a device that meets these criteria, none has been reported to date to our knowledge. To address this deficiency, we developed an implantable reservoir capped by a nanocomposite membrane whose permeability was modulated by irradiation with a near-infrared laser. Irradiated devices could exhibit sustained on-state drug release for at least 3 h, and could reproducibly deliver short pulses over at least 10 cycles, with an on/off ratio of 30. Devices containing aspart, a fast-acting insulin analog, could achieve glycemic control after s.c. implantation in diabetic rats, with reproducible dosing controlled by the intensity and timing of irradiation over a 2-wk period. These devices can be loaded with a wide range of drug types, and therefore represent a platform technology that might be used to address a wide variety of clinical indications.

Locally applied leptin induces regional aortic wall degeneration preceding aneurysm formation in apolipoprotein E-deficient mice.

OBJECTIVE: Leptin promotes atherosclerosis and vessel wall remodeling. As abdominal aortic aneurysm (AAA) formation involves tissue remodeling, we hypothesized that local leptin synthesis initiates and promotes this process. METHODS AND RESULTS: Human surgical AAA walls were analyzed for antigen and mRNA levels of leptin and leptin receptor, as well as mRNA for matrix metalloproteinases (MMP)-9 and MMP-12. Leptin and leptin receptor antigen were evident in all AAAs, and leptin, MMP-9, and MMP-12 mRNA was increased relative to age-matched nondilated controls. To simulate in vivo local leptin synthesis, ApoE(-/-) mice were subjected to a paravisceral periaortic application of low-dose leptin. Leptin-treated aortas exhibited decreased transforming growth factor-ß and increased MMP-9 mRNA levels 5 days after surgery, and leptin receptor mRNA was upregulated by day 28. Serial ultrasonography demonstrated accelerated regional aortic diameter growth after 28 days, correlating with local medial degeneration, increased MMP-9, MMP-12, and periadventitial macrophage clustering. Furthermore, the combination of local periaortic leptin and systemic angiotensin II administration augmented medial MMP-9 synthesis and aortic aneurysm size. CONCLUSIONS: Leptin is locally synthesized in human AAA wall. Paravisceral aortic leptin in ApoE(-/-) mice induces local medial degeneration and augments angiotensin II-induced AAA, thus suggesting novel mechanistic links between leptin and AAA formation.

Bioadhesive microneedle patches for tissue sealing.

Sealing of soft tissues prevents leakage of gas and liquid, closes wounds, and promotes healing and is, therefore, of great significance in the clinical and medical fields. Although various formulations have been developed for reliable sealing of soft tissue, tradeoffs between adhesive properties, degradation profile, and tissue toxicity limit their clinical use. Hydrogel-based adhesives, for example, are highly biocompatible but adhere very weakly to the tissue and degrade quickly, while oxidized cellulose patches are poorly absorbed and may cause healing complications postoperatively. Here, we present a novel strategy for tissue sealing based on bioadhesive microneedle patches that can spontaneously adhere to tissue surface through electrostatic interactions and swell within it. A series of microneedle patches made of pullulan, chitosan, Carbopol, poly (lactic-co-glycolic acid), and a Carbopol/chitosan combination were fabricated and characterized for their use in tissue sealing. The effect of microneedle composition on the fabrication process, physical and mechanical properties, in vitro cytotoxicity, and in vivo biocompatibility were examined. The needle structure enables microneedles to strongly fix onto various tissues via physical interlocking, while their adhesive properties improve staying time and sealing capabilities. The microneedle patch comprising Carbopol needles and chitosan as a second pedestal layer presented the best results in terms of sealing and adhesion, a consequence of the needle's swelling and adhesion features combined with the supportive chitosan base layer. Finally, single Carbopol/chitosan patches stopped intense liver bleeding in a rat model significantly quicker and with less blood loss compared with commercial oxidized cellulose patches. These microneedles can be considered a promising cost-effective platform for adhering and sealing tissues as they can be applied quickly and painlessly, and require less trained medical staff and equipment.

A Stiff Injectable Biodegradable Elastomer.

Injectable materials often have shortcomings in mechanical and drug-eluting properties that are attributable to their high water contents. A water-free, liquid four-armed PEG modified with dopamine end groups is described which changed from liquid to elastic solid by reaction with a small volume of Fe3+ solution. The elastic modulus and degradation times increased with increasing Fe3+ concentrations. Both the free base and the water-soluble form of lidocaine could be dissolved in the PEG4-dopamine and released in a sustained manner from the cross-linked matrix. PEG4-dopamine was retained in the subcutaneous space in vivo for up to 3 weeks with minimal inflammation. This material's tailorable mechanical properties, biocompatibility, ability to incorporate hydrophilic and hydrophobic drugs and release them slowly are desirable traits for drug delivery and other biomedical applications.

Long-lasting antifouling coating from multi-armed polymer.

We describe a new antifouling surface coating, based on aggregation of a short amphiphilic four-armed PEG-dopamine polymer into particles and on surface binding by catechol chemistry. An unbroken and smooth polymeric coating layer with an average thickness of approximately 4 µm was formed on top of titanium oxide surfaces by a single step reaction. Coatings conferred excellent resistance to protein adhesion. Cell attachment was completely prevented for at least eight weeks, although the membranes themselves did not appear to be intrinsically cytotoxic. When linear PEG or four-armed PEG of higher molecular weight were used, the resulting coatings were inferior in thickness and in preventing protein adhesion. This coating method has potential applicability for biomedical devices susceptible to fouling after implantation.

Biodistribution and function of coupled polymer-DNA origami nanostructures.

Spatial control over the distribution of therapeutics is a highly desired feature, which could limit the side effects of many drugs. Here we describe a nanoscale agent, fabricated from a coupled polymer-DNA origami hybrid that exhibits stability in serum and slow diffusion through tissues, in a manner correlating with shape and aspect ratio. Coupling to fragments of polyethylene glycol (PEG) through polyamine electrostatic interactions resulted in marked stability of the agents in-vivo, with > 90% of the agents maintaining structural integrity 5 days following subcutaneous injection. An agent functionalized with aptamers specific for human tumor necrosis factor TNF-alpha, significantly abrogated the inflammatory response in a delayed-type hypersensitivity model in humanized TNF-alpha mice. These findings highlight polymer-DNA hybrid nanostructures as a programmable and pharmacologically viable update to mainstream technologies such as monoclonal antibodies, capable of exerting an additional layer of control across the spatial dimension of drug activity.

Design and Evaluation of Dissolvable Microneedles for Treating Atopic Dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused predominantly by immune dysregulation. The global impact of AD continues to increase, making it not only a significant public health issue but also a risk factor for progression into other allergic phenotype disorders. Treatment of moderate-to-severe symptomatic AD involves general skin care, restoration of the skin barrier function, and local anti-inflammatory drug combinations, and may also require systemic therapy, which is often associated with severe adverse effects and is occasionally unsuitable for long-term use. The main objective of this study was to develop a new delivery system for AD treatment based on dissolvable microneedles containing dexamethasone incorporated in a dissolvable polyvinyl alcohol/polyvinylpyrrolidone matrix. SEM imaging of the microneedles showed well-structured arrays comprising pyramidal needles, fast drug release in vitro in Franz diffusion cells, an appropriate mechanical strength recorded with a texture analyzer, and low cytotoxicity. Significant clinical improvements, including in the dermatitis score, spleen weights, and clinical scores, were observed in an AD in vivo model using BALB/c nude mice. Taken together, our results support the hypothesis that microneedle devices loaded with dexamethasone have great potential as a treatment for AD and possibly for other skin conditions as well.

Liquid Copolymers as Biodegradable Surgical Sealant.

Surgical sealants are widely used to prevent seepage of fluids and liquids, promote hemostasis, and close incisions. Despite the remarkable progress the field of biomaterials has undergone, the clinical uses of surgical sealants are limited because of their short persistence time in vivo, toxicity, and high production costs. Here, the development of two complementary neat (solvent-free) prepolymers, PEG4 -PLGA-NHS and PEG4 -NH2 , that harden upon mixing to yield an elastic biodegradable sealant is presented. The mechanical and rheological properties and cross-linking rate can be controlled by varying the ratio between the two prepolymers. The tested sealants show a longer persistence time compared with fibrin glue, minimal cytotoxicity in vitro, and excellent biocompatibility in vivo. The neat, multiarmed approach demonstrated here improves the mechanical and biocompatibility properties and provides a promising tissue sealant solution for wound closure in future surgical procedures.

Bacillus subtilis in PVA Microparticles for Treating Open Wounds.

Open wound dressings should provide a moist environment, protect the wound from bacterial contamination, and shield it from further damage. These requirements, however, are hard to accomplish since such wounds are colonized by pathogenic bacteria, including resistant species such as methicillin-resistant Staphylococcus aureus (MRSA). A new approach for treating open wounds that is based on sticky and dissolvable polyvinyl alcohol (PVA) microparticles containing live Bacillus subtilis (B. subtilis) is described. Microparticles, fabricated by the spray-drying technique, were administered directly to an open wound while B. subtilis continuously produced and secreted antimicrobial molecules. B. subtilis in PVA microparticles demonstrated remarkable antibacterial activity against MRSA and S. aureus. In in vivo experiments, both B. subtilis and empty PVA microparticles were effective in decreasing healing time; however, B. subtilis microparticles were more effective during the first week. There was no evidence of skin irritation, infection, or other adverse effects during the 15 day postoperative observation period. This concept of combining live secreting bacteria within a supportive delivery system shows great promise as a therapeutic agent for open wounds and other infectious skin disorders.

Advanced human-relevant in vitro pulmonary platforms for respiratory therapeutics.

Over the past years, advanced in vitro pulmonary platforms have witnessed exciting developments that are pushing beyond traditional preclinical cell culture methods. Here, we discuss ongoing efforts in bridging the gap between in vivo and in vitro interfaces and identify some of the bioengineering challenges that lie ahead in delivering new generations of human-relevant in vitro pulmonary platforms. Notably, in vitro strategies using foremost lung-on-chips and biocompatible "soft" membranes have focused on platforms that emphasize phenotypical endpoints recapitulating key physiological and cellular functions. We review some of the most recent in vitro studies underlining seminal therapeutic screens and translational applications and open our discussion to promising avenues of pulmonary therapeutic exploration focusing on liposomes. Undeniably, there still remains a recognized trade-off between the physiological and biological complexity of these in vitro lung models and their ability to deliver assays with throughput capabilities. The upcoming years are thus anticipated to see further developments in broadening the applicability of such in vitro systems and accelerating therapeutic exploration for drug discovery and translational medicine in treating respiratory disorders.

Extrinsic Factors Shaping the Skin Microbiome.

Human skin, our most environmentally exposed organ, is colonized by a vast array of microorganisms constituting its microbiome. These bacterial communities are crucial for the fulfillment of human physiological functions such as immune system modulation and epidermal development and differentiation. The structure of the human skin microbiome is established during the early life stages, starting even before birth, and continues to be modulated throughout the entire life cycle, by multiple host-related and environmental factors. This review focuses on extrinsic factors, ranging from cosmetics to the environment and antibacterial agents, as forces that impact the human skin microbiome and well-being. Assessing the impact of these factors on the skin microbiome will help elucidate the forces that shape the microbial populations we coexist with. Furthermore, we will gain additional insight into their tendency to stimulate a healthy environment or to increase the propensity for skin disorder development.

Functionalized Multiarmed Polycaprolactones as Biocompatible Tissue Adhesives.

Existing tissue adhesives have a trade-off between adhesive strength and biocompatibility. Here, we report a series of biocompatible multiarmed polycaprolactones (PCL) as tissue adhesives that can be released from a hot glue gun and the length of each arm was kept at ∼2-3 kg mol-1 in all the polymers. The adhesion properties were dependent on the number of functionalized (N-hydroxysuccinimide ester (NHS), aldehyde (CHO), and isocyanate (NCO)) arms of the multiarmed polymers. The more arms, the higher the adhesion strength. For example, the adhesion strength in binding cut rat skin increased from 2.3 N cm-2 for 2PCL-NHS to 11.2 N cm-2 for 8-PCL-NHS. CHO- and NCO-modified 8PCL also had suitable adhesive properties. All the multiarmed polymers had minimal cytotoxicity in vitro and good biocompatibility in vivo, suggesting their potential as promising alternative surgical adhesives.

Anhydride prodrug of ibuprofen and acrylic polymers.

The objective of this study was to synthesize anhydride prodrugs for carboxylic-acid-bearing agents such as non-steroidal anti-inflammatory drugs, shield the carboxylic acid group from irritative effects, and obtain sustained release patterns. Ibuprofen was used as a representative drug for anhydride derivatization. Conjugates of ibuprofen with carboxylic acid moieties of different acrylic polymers were prepared by dehydration reaction using acetic anhydride. Products were characterized by infrared spectroscopy, nuclear magnetic resonance, and scanning electron microscopy followed by preparation of microspheres with different sizes from the conjugate Eudragit L-100-ibuprofen. The drug release was monitored by high-performance liquid chromatography. Ibuprofen was bound to the polymers via an anhydride bond in high reaction yields (75-95%) with drug loading of up to 30% (w/w). These anhydride derivatives hydrolyzed and release the drug at different periods ranging from 1 to 5 days, depending on the hydrophobicity and the cross-linking of the conjugates. The release of drug from the microspheres was correlated to their size and ranged from 2 to almost 8 days. This study demonstrates the promise of anhydride prodrug for extending drug action while shielding the carboxylic acid group.

Two-component cross-linkable gels for fabrication of solid oral dosage forms.

Current three-dimensional (3D) printing techniques involve the solidification of the injected materials by means of UV irradiation, evaporation of organic solvents, or harsh heating and cooling processes. These methods limit the printing of many sensitive bio-active molecules such as proteins. We describe a novel 3D printing technique based on two complementary liquid copolymers, PEG4-PCL-SC and PEG4-PCL-NH2, that are injected in a coordinated fashion and react with each other to form a pre-designed 3D pill. Printed pills swelled about 400% over 3 h, followed by moderate disintegration. Both prednisone and bovine serum albumin were incorporated into the printed pill, but while most of the prednisone was released depending on the ratio between the two complementary pre-polymers, only 40% of the bovine serum albumin was released from the pill. This unique 3D printing apparatus can be used to produce pills at home when the required medication does not handle current production techniques well and may have other possible biomedical applications. However, before this system can be considered for pharmaceutical applications, the low printing resolution, attributable to the slow gelation kinetics and the viscosity of the pre-polymers, should be addressed.

Oral malodor reduction by a palatal mucoadhesive tablet containing herbal formulation.

OBJECTIVE: The aim of the present study was to test the effect of a palatal mucoadhesive tablet containing an herbal formulation on oral malodor production and volatile sulfide compound (VSC) levels, and to evaluate its antimicrobial activity. METHODS: A total of 56 healthy young volunteers participated in experiments 1 and 2. The palatal adhesive tablets were prepared with different active ingredients (herbal formulation, zinc and chlorhexidine), or without an active ingredient as control (placebo). Measurement included odor judge scores (two judges) and VSC readings by a sulfide monitor (Halimeter). In experiment 3, the antimicrobial activity of the herbal formulation ingredients (i.e. sage, Echinacea, Lavender and Mastic gum) were tested against three oral pathogens (Streptoccocus mutans, Porphyromonas gingivalis and Candida albicans) by the agar diffusion test. RESULTS: Application of the palatal adhesive tablets containing herbal formulation resulted in a significant reduction in both oral malodor scores (p<0.001) and VSC levels (p=0.013). Herbal formulation showed higher significance in VSC reduction (p=0.001), as compared to zinc and chlorhexidine (p=0.024 and 0.032, respectively). Sage, Lavender and Mastic gum showed antimicrobial activity against all three oral pathogens. CONCLUSIONS: Results of the present study suggest that the palatal adhesive tablets containing herbal formulation may serve as an effective means of treatment for patients complaining of oral malodor.

Efficacy of a mucoadhesive patch compared with an oral solution for treatment of aphthous stomatitis.

OBJECTIVE: The purpose of this study was to evaluate the efficacy and tolerability of a mucoadhesive patch compared with a pain-relieving oral solution for the treatment of aphthous stomatitis. METHODS: Patients with active aphthous stomatitis were randomly treated either once a day with a mucoadhesive patch containing citrus oil and magnesium salts (n = 26) or three times a day with an oral solution containing benzocaine and compound benzoin tincture (n = 22). All patients were instructed to apply the medication until pain had resolved, and completed a questionnaire detailing multiple clinical parameters followed by an evaluation of the treatment. RESULTS: The mucoadhesive patch was found to be more effective than the oral solution in terms of healing time (mean +/- SD: 36.0 +/- 22.8 hours vs 134.7 +/- 57.7, p < 0.001) and pain intensity after 12 and 24 hours (3.7 +/- 2.8 vs 6.3 +/- 2.6, p = 0.003, and 2.3 +/- 2.7 vs 5.7 +/- 2.5, p < 0.001, respectively). Local adverse effects 1 hour after treatment were significantly (p < 0.01) less frequent among the mucoadhesive patch patients compared with the oral solution patients. CONCLUSIONS: The mucoadhesive patch was found to be significantly more effective and better tolerated than the oral solution in the treatment of aphthous stomatitis.