Photocurable platelet rich plasma bioadhesives

Ultrafast gelling bioadhesive based on blood plasma and gelatin for wound closure and healing

Tissue adhesives offer a plethora of advantages in achieving efficient wound closure over conventional sutures and staples. Such materials are of great value, especially in cases where suturing could potentially damage tissues or compromise blood flow or in cases of hard-to-reach areas. Besides providing wound closure, the tissue adhesives must also facilitate wound healing. Previously, plasma-based tissue adhesives and similar bioinspired strategies have been utilized to aid in wound healing. Still, their application is constrained by factors such as high cost, diminished biocompatibility, prolonged gelation times, inadequate swelling, quick resorption, as well as short-term and inconsistent efficacy. To address these limitations, we report the development of a highly biocompatible and ultrafast-gelling tissue adhesive hydrogels. Freeze-dried platelet-rich plasma, heat-denatured freeze-dried platelet-poor plasma, and gelatin were utilized as the base matrix. Gelation was initiated by adding tetrakis hydroxymethyl phosphonium chloride. The fabricated gels displayed rapid gelation (3-4 s), low swelling, increased proliferation, and migration against L929 cells and had porcine skin tissue adhesion strength similar to that of plasma-based commercial glue (Tisseel®).

Biological and Adhesive Properties of an Autologous Protein-Based Fibrin Sealant for Ophthalmological Applications

Purpose

The aim of this study was to evaluate the biological and adhesive properties of a new autologous sealant based on plasma rich in growth factors (PRGF), named E-Sealant.

Methods

Conventional PRGF and a commercial fibrin sealant (Tisseel) were included as controls. The hematological and protein content of E-Sealant was determined. Its bioactivity and biocompatibility were tested for human keratocytes (HKs). To evaluate its adhesion and regenerative capacity, E-Sealant was used on an animal model of conjunctival autograft surgery and compared to Tisseel.

Results

E-Sealant presented a high growth factor content with levels similar to those of conventional PRGF. E-Sealant induced proliferative and migratory activity on HK cells equivalent to PRGF. Although autologous membranes induced the proliferation of HKs, cells cultured over Tisseel did not adhere nor proliferate. HK cells showed increased number and flattened morphology over PRGF and E-Sealant compared to scarce and round-shape cells detected in Tisseel. Conjunctival autograft glued with E-Sealant adhered successfully, whereas Tisseel application formed irregular clots. During follow-up, both adhesives showed good integration and no dehiscence. However, Tisseel-treated samples presented slightly increased hemorrhage and inflammation. In contrast to Tisseel, E-Sealant-treated autografts presented a continuous layer of non-keratinized stratified squamous epithelium. Inflammatory infiltrates were minimal in E-Sealant-treated conjunctiva, whereas the Tisseel group showed noticeable immune reactions. Unlike Tisseel-treated grafts, E-Sealant presented low immunoreactivity for smooth muscle actin (SMA), suggesting decreased fibrotic tissue formation.

Conclusions

E-Sealant presents optimal biological and adhesive properties suitable for use as an ophthalmic glue, with regenerative purposes superior to commercial fibrin sealants.

Translational Relevance

Our study analyzed the characterization and biological activity of a new autologous fibrin sealant in ocular surface cells and in an animal model in which the adhesive and regenerative properties of the fibrin sealant were evaluated.

Synthesis and Evaluation of Metal Lipoate Adhesives

The development of new bioadhesives with integrated properties remains an unmet clinical need to replace staples or sutures. Current bioadhesives do not allow electronic activation, which would allow expansion into laparoscopic and robotic surgeries. To address this deficiency, voltage-activated adhesives have been developed on both carbene- and catechol-based chemical precursors. Herein, a third platform of voltage-activated adhesive is evaluated based on lipoic acid, a non-toxic dithiolane found in aerobic metabolism and capable of ring-opening polymerization. The electro-rheological and adhesive properties of lithium, sodium, and potassium salts of lipoic acid are applied for wet tissue adhesion. At ambient conditions, potassium lipoate displays higher storage modulus than lithium or sodium salt under similar conditions. Voltage stimulation significantly improves gelation kinetics to Na- and K-lipoates, while Li-lipoate is found to not require voltage stimulation for gelation. Lap shear adhesion strength on wetted collagen substrates reveals that the synthetic metal lipoates have comparable adhesion strength to fibrin sealants without viral or ethical risks.

Bacterial cellulose adhesive patches designed for soft mucosal interfaces

The wet environment in the oral cavity is challenging for topical disease management approaches. The compromised material properties leading to weak adhesion and short retention (<8 h) in such environment result in frequent reapplication of the therapeutics. Composites of bacterial cellulose (BC) and carbene-based bioadhesives attempt to address these shortcomings. Previous designs comprised of aqueous formulations. The current design, for the first time, presents dry, shelf-stable cellulose patches for convenient ready-to-use application. The dry patches simultaneously remove tissue surface hydration while retaining carbene-based photocuring and offers on-demand adhesion. The dry patch prototypes are optimized by controlling BC/adhesive mole ratios and dehydration technique. The adhesion strength is higher than commercial denture adhesives on soft mucosal tissues. The structural integrity is maintained for a minimum of 7 days in aqueous environment. The patches act as selective nanoporous barrier against bacteria while allowing permeation of proteins. The results support the application of BC-based adhesive patches as a flexible platform for wound dressings, drug depots, or combination thereof.

Fibrillated bacterial cellulose liquid carbene bioadhesives for mimicking and bonding oral cavity surfaces

Topical treatments for oral wounds and infections exhibit weak adhesion to wet surfaces which results in short retention duration (6-8 hours), frequent dosing requirement and patient incompatibility. To address these limitations, aqueous composites made of fibrillated bacterial cellulose and photoactive bioadhesives are designed for soft epithelial surfaces. The aqueous composites crosslink upon photocuring within a minute and exhibit a transition from viscous to elastic adhesive hydrogels. The light-cured composites have shear moduli mimicking oral mucosa and other soft tissues. The tunable adhesion strength ranges from 3 to 35 kPa on hydrated tissue-mimicking surfaces (collagen film). The results support the application of bacterial cellulose hydrogel systems for potential treatment of mucosal wounds.

Hydrophobic Bioadhesive Composites for Human Motion Detection

Conductive hydrogels are rapidly rising as sensing materials for bioelectronics applications, but lack mechanical and adhesion strength due to their excess water content. We propose a diazirine-grafted polycaprolactone adhesive (CaproGlu)/carbon nanotubes (CNTs) composite that can provide wet adhesion and strong mechanical properties at the tissue-machine interface. The introduced CNTs not only reinforced the CaproGlu, but also formed electrically conducting pathways. The CaproGlu composites exhibited conductivity of 0.1 S m^-1 and a charge storage capacity of 5 μC cm^-2. The resulting composites are biocompatible and can be used as strain sensors to detect mechanical deformations.

Bacterial cellulose adhesive composites for oral cavity applications

Topical approaches to oral diseases require frequent dosing due to limited retention time. A mucoadhesive drug delivery platform with extended soft tissue adhesion capability of up to 7 days is proposed for on-site management of oral wound. Bacterial cellulose (BC) and photoactivated carbene-based bioadhesives (PDz) are combined to yield flexible film platform for interfacing soft tissues in dynamic, wet environments. Structure-activity relationships evaluate UV dose and hydration state with respect to adhesive strength on soft tissue mimics. The bioadhesive composite has an adhesion strength ranging from 7 to 17 kPa and duration exceeding 48 h in wet conditions under sustained shear forces, while other mucoadhesives based on hydrophilic macromolecules exhibit adhesion strength of 0.5-5 kPa and last only a few hours. The work highlights the first evaluation of BC composites for mucoadhesive treatments in the buccal cavity.

Minimally invasive electroceutical catheter for endoluminal defect sealing

Surgical repair of lumen defects is associated with periprocedural morbidity and mortality. Endovascular repair with tissue adhesives may reduce host tissue damage, but current bioadhesive designs do not support minimally invasive deployment. Voltage-activated tissue adhesives offer a new strategy for endoluminal repair. To facilitate the clinical translation of voltage-activated adhesives, an electroceutical patch (ePATCH) paired with a minimally invasive catheter with retractable electrodes (CATRE) is challenged against the repair of in vivo and ex vivo lumen defects. The ePATCH/CATRE platform demonstrates the sealing of lumen defects up to 2 millimeters in diameter on wet tissue substrates. Water-tight seals are flexible and resilient, withstanding over 20,000 physiological relevant stress/strain cycles. No disruption to electrical signals was observed when the ePATCH was electrically activated on the beating heart. The ePATCH/CATRE platform has diverse potential applications ranging from endovascular treatment of pseudo-aneurysms/fistulas to bioelectrodes toward electrophysiological mapping.