A multifunctional polymeric coating with self-adsorbed, antifouling and in situ remineralization properties for caries management.

Dental caries is a biofilm-induced bacterial infectious oral disease, where the early attachment of proteins and pathogenic bacteria to tooth surfaces has been known as the main cause of biofilm formation. Typically, dental caries is commonly accompanied by mineral depletion of enamels, thus causing dental demineralization. Multifunctional materials are highly attractive candidates for treating dental caries. Herein, we successfully synthesized diblock copolymers poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAsp) and modified them with alendronate sodium (ALN) to serve as bioactive bifunctional coatings (PEG-PAsp-ALN) on teeth. The PEG segments are employed for inhibiting proteins and bacterial adhesion. In addition, due to the presence of both PAsp and ALN, a synergistically strong binding capacity could be achieved with the tooth surface, thus promoting rapid and thorough remineralization in situ, while maintaining excellent safety. The combination treatment can significantly suppress the biofilm formation, which is beneficial for alleviating the demineralization of enamels caused by bacteria, and further, facilitate remineralization in situ. This approach thus demonstrates the potential of the copolymer PEG-PAsp-ALN coating as a multifunctional protecting layer on the tooth surface for high-efficiency prevention and treatment of dental caries.

Two-in-one strategy: a remineralizing and anti-adhesive coating against demineralized enamel.

Tooth enamel is prone to be attacked by injurious factors, leading to a de/remineralization imbalance. To repair demineralized enamel and prevent pulp inflammation caused by biofilm accumulation, measures are needed to promote remineralization and inhibit bacterial adhesion on the tooth surface. An innovative material, poly (aspartic acid)-polyethylene glycol (PASP-PEG), was designed and synthesized to construct a mineralizing and anti-adhesive surface that could be applied to repair demineralized enamel. A cytotoxicity assay revealed the low cytotoxicity of synthesized PASP-PEG. Adsorption results demonstrated that PASP-PEG possesses a high binding affinity to the hydroxyapatite (HA)/tooth surface. In vitro experiments and scanning electron microscopy (SEM) demonstrated a strong capacity of PASP-PEG to induce in situ remineralization and direct the oriented growth of apatite nanocrystals. Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and Vickers hardness tests demonstrated that minerals induced by PASP-PEG were consistent with healthy enamel in Ca/P ratio, crystal form and surface micro-hardness. Contact angle tests and bacterial adhesion experiments demonstrated that PASP-PEG yielded a strong anti-adhesive effect. In summary, PASP-PEG could achieve dual effects for enamel repair and anti-adhesion of bacteria, thereby widening its application in enamel repair.

Rational Design of Rapidly Separating Dissolving Microneedles for Precise Drug Delivery by Balancing the Mechanical Performance and Disintegration Rate.

The precise delivery of traditional dissolving microneedles (TDMNs) is often limited by the incomplete insertion due to the skin deformation, and the topical irritation is inevitable after long application, which ultimately results in compromised therapeutic efficacy. The aim of this study is to develop a rapidly separating dissolving microneedles (RSDMNs) system to achieve precise drug delivery. Therapeutic molecules are concentrated in the needle tip, while the blank separating part allows it to counteract skin indentation and rapidly separate from the base part. For rational design of an ideal separating part, and the molecular interactions between polymer and sugar are explored to make a good balance between mechanical performance and disintegration rate. The optimal RSDMNs can rapidly disintegrate in the mimic skin within 30 s, and the generated micropores in the skin reseal quickly. The ex vivo drug permeation of RSDMNs is significantly higher than that of TDMNs due to the complete needle imbed aided by the separating part. Furthermore, RSDMNs exhibit excellent in vivo anti-inflammation effect by remarkably down regulating the expression of TNF-α, IL-1ß, and IL-6. In conclusion, the RSDMNs can reach precise drug delivery in a short time, which are more reliable for the self-administration strategy in the future.