Bioadhesive Nanoaggregates Based on Polyaspartamide-g-C18/DOPA for Wound Healing

Oxidative Stress-Induced Silver Nano-Carriers for Chemotherapy

Recently, silver nanoparticles (AgNPs) have been extensively explored in a variety of biological applications, especially cancer treatment. AgNPs have been demonstrated to exhibit anti-tumor effects through cell apoptosis. This study intends to promote cell apoptosis further by increasing oxidative stress. AgNPs are encapsulated by biocompatible and biodegradable polyaspartamide (PA) (PA-AgNPs) that carries the anti-cancer drug Doxorubicin (Dox) to inhibit cancer cells primarily. PA-AgNPs have an average hydrodynamic diameter of 130 nm, allowing them to move flexibly within the body. PA-AgNPs show an excellent targeting capacity to cancer cells when they are conjugated to biotin. In addition, they release Dox efficiently by up to 88% in cancer environments. The DCFDA experiment demonstrates that the Dox-carried PA-AgNPs generate reactive oxidation species intensively beside 4T1 cells. The MTT experiment confirms that PA-AgNPs with Dox may strongly inhibit 4T1 cancer cells. Furthermore, the in vivo study confirms that PA-AgNPs with Dox successfully inhibit tumors, which are about four times smaller than the control group and have high biosafety that can be applied for chemotherapy.

Cohesion mechanisms for bioadhesives

Due to the nature of non-invasive wound closure, the ability to close different forms of leaks, and the potential to immobilize various devices, bioadhesives are altering clinical practices. As one of the vital factors, bioadhesives' strength is determined by adhesion and cohesion mechanisms. As well as being essential for adhesion strength, the cohesion mechanism also influences their bulk functions and the way the adhesives can be applied. Although there are many published reports on various adhesion mechanisms, cohesion mechanisms have rarely been addressed. In this review, we have summarized the most used cohesion mechanisms. Furthermore, the relationship of cohesion strategies and adhesion strategies has been discussed, including employing the same functional groups harnessed for adhesion, using combinational approaches, and exploiting different strategies for cohesion mechanism. By providing a comprehensive insight into cohesion strategies, the paper has been integrated to offer a roadmap to facilitate the commercialization of bioadhesives.

Poly(amino acid) based fibrous membranes with tuneable in vivo biodegradation

In this work two types of biodegradable polysuccinimide-based, electrospun fibrous membranes are presented. One contains disulfide bonds exhibiting a shorter (3 days) in vivo biodegradation time, while the other one has alkyl crosslinks and a longer biodegradation time (more than 7 days). According to the mechanical measurements, the tensile strength of the membranes is comparable to those of soft the connective tissues and visceral tissues. Furthermore, the suture retention test suggests, that the membranes would withstand surgical handling and in vivo fixation. The in vivo biocompatibility study demonstrates how membranes undergo in vivo hydrolysis and by the 3rd day they become poly(aspartic acid) fibrous membranes, which can be then enzymatically degraded. After one week, the disulfide crosslinked membranes almost completely degrade, while the alkyl-chain crosslinked ones mildly lose their integrity as the surrounding tissue invades them. Histopathology revealed mild acute inflammation, which diminished to a minimal level after seven days.

Controllable performance of a dopamine-modified silk fibroin-based bio-adhesive by doping metal ions

Bio-adhesives are essential for wound healing because of their convenience and safety. Although widely used as biomaterials, silk fibroin's (SF's) further application as bio-adhesive is hindered due to its weak stickiness with tissue and slow gelation speed. Here, a dopamine-modified SF-based bio-adhesive is fabricated by using genipin as the chemical cross-linking agent. Furthermore, metal ions have been used to adjust the adhesion property of the bio-adhesive. The experimental results shows that the dopamine-modified SF-based composite holds a better stickiness except slow gelation speed. The doping of Cu²⁺and Fe³⁺can accelerate the gelation of the bio-adhesive. Compared with Cu²⁺, Fe³⁺has a stronger effect on the gelation speed of the bio-adhesive, which is positive correlative to the concentration of Fe³⁺. The adhesive has injectability and degradability. In addition, the SF-based adhesive has good biocompatibility and good improvement for cell migrationin vitro. The SF-based bio-adhesive holds potential application in the field of rapid fixation of wounds.

Poly(aspartic acid) in Biomedical Applications: From Polymerization, Modification, Properties, Degradation, and Biocompatibility to Applications

Poly(aspartic acid) (PASP) is an anionic polypeptide that is a highly versatile, biocompatible, and biodegradable polymer that fulfils key requirements for use in a wide variety of biomedical applications. The derivatives of PASP can be readily tailored via the amine-reactive precursor, poly(succinimide) (PSI), which opens up a large window of opportunity for the design and development of novel biomaterials. PASP also has a strong affinity with calcium ions, resulting in complexation, which has been exploited for bone targeting and biomineralization. In addition, recent studies have further verified the biocompatibility and biodegradability of PASP-based polymers, which is attributed to their protein-like structure. In light of growing interest in PASP and its derivatives, this paper presents a comprehensive review on their synthesis, characterization, modification, biodegradation, biocompatibility, and applications in biomedical areas.

Sprayable hydrogel dressing accelerates wound healing with combined reactive oxygen species-scavenging and antibacterial abilities

Wound management poses a considerable economic burden on the global healthcare system, considering the impacts of wound infection, delayed healing and scar formation. To this end, multifunctional dressings based on hydrogels have been developed to stimulate skin healing. Herein, we describe the design, fabrication, and characterization of a sprayable hydrogel-based wound dressing loaded with cerium oxide nanoparticles (CeONs) and an antimicrobial peptide (AMP), for combined reactive oxygen species (ROS)-scavenging and antibacterial properties. We adopted a mussel-inspired strategy to chemically conjugate gelatin with dopamine motifs and prepared a hydrogel dressing with improved binding affinity to wet skin surfaces. Additionally, the release of AMP from the hydrogel demonstrated rapid release ablation and contact ablation against four representative bacterial strains, confirming the desired antimicrobial activities. Moreover, the CeONs-loaded hydrogel dressing exhibited favorable ROS-scavenging abilities. The biocompatibility of the multifunctional hydrogel dressing was further proven in vitro by culturing with HaCaT cells. Overall, the benefits of the developed hydrogel wound dressing, including sprayability, adhesiveness, antimicrobial activity, as well as ROS-scavenging and skin-remodeling ability, highlight its promissing translational potentials in wound management. STATEMENT OF SIGNIFICANCE: Various hydrogel-based wound-dressing materials have been developed to stimulate wound healing. However, from the clinical perspective, few of the current wound dressings meet all the intended multifunctional requirements of preventing infection, promoting rapid wound closure, and minimizing scar formation, while simultaneously offering the convenience of application. In the current study, we adopted a mussel-inspired strategy to functionalize the GelMA hydrogels with DOPA to fabricate GelMA-DOPA hydrogel which exhibited an enhanced binding affinity for wound surfaces, AMP HHC-36 and CeONs are further encapsulated into the GelMA-DOPA hydrogel to confer the hydrogel wound dressing with antimicrobial and ROS-scavenging abilities. The GelMA-DOPA-AMP-CeONs dressing offered the benefits of sprayability, adhesiveness, antimicrobial activity, as well as ROS-scavenging and skin-remodeling ability, which might address the therapeutic and economic burdens associated with chronic wound treatment and management.

A dopamine-functionalized aqueous-based silk protein hydrogel bioadhesive for biomedical wound closure

The functionalization of a PEGylated silk protein hydrogel with dopamine significantly improved its wet adhesive strength.

ABA-type triblock copolymer micellar system with lower critical solution temperature-type sol-gel transition

A temperature sensitive sol-gel transition induced by the self-assembly of amphiphilic copolymers and its application in industry have been the objects of increasing study. We demonstrate here a two-step, reversible addition-fragmentation chain transfer (RAFT) polymerization of an ABA-type copolymer consisting of poly(N,N-dimethylacrylamide)-b-poly(diacetone acrylamide)-b-poly(N,N-dimethylacrylamide) (PDMAA-b-PDAAM-b-PDMAA). This copolymer can be easily dispersed in water, and this dispersion is critical for its lower critical solution temperature (LCST)-type sol-gel transition, which was monitored using dynamic light scattering (DLS), transmission electron microscopy (TEM), and rheology analysis, in addition to temperature-dependent ¹H nuclear magnetic resonance (¹H NMR) and Fourier transform infrared spectroscopy (FTIR). Results revealed an abnormal sphere-to-worm micellar transition of this ABA copolymer at the LCST point, which could be affected by the length of the PDAAM block (B-block), the length as well as the distribution of the PDMAA block (A-block), and the concentration of the copolymer dispersion. Thus, copolymer dispersion could be feasibly used for drug loading at a low temperature, which could then be transformed into a gel at an elevated temperature. The loading and controllable release of the model drug of paracetamol into and out of a copolymer gel was further determined. The sustained release behavior was also studied using the Rigter-Peppas model.

Emerging biomedical applications of polyaspartic acid-derived biodegradable polyelectrolytes and polyelectrolyte complexes

A summary of positive biomedical attributes of biodegradable polyelectrolytes (PELs) prepared from aspartic acid is provided. The utility of these PELs in emerging applications such as biomineralization modulators, antimycobacterials, biocompatible cell encapsulants and tissue adhesives is highlighted.

Mussel-inspired hydrogel tissue adhesives for wound closure

Tissue adhesives have been introduced as a promising alternative for the traditional wound closure method of suturing.