Mussel-inspired resilient hydrogels with strong skin adhesion and high-sensitivity for wearable device.

Stretchable and self-adhesive conductive hydrogels hold significant importance across a wide spectrum of applications, including human-machine interfaces, wearable devices, and soft robotics. However, integrating multiple properties, such as high stretchability, strong interfacial adhesion, self-healing capability, and sensitivity, into a single material poses significant technical challenges. Herein, we present a multifunctional conductive hydrogel based on poly(acrylic acid) (PAA), dopamine-functionalized pectin (PT-DA), polydopamine-coated reduction graphene oxide (rGO-PDA), and Fe3+ as an ionic cross-linker. This hydrogel exhibits a combination of high stretchability (2000%), rapid self-healing (~ 94% recovery in 5 s), and robust self-adhesion to various substrates. Notably, the hydrogel demonstrates a remarkable skin adhesion strength of 85 kPa, surpassing previous skin adhesive hydrogels. Furthermore, incorporating rGO within the hydrogel network creates electric pathways, ensuring excellent conductivity (0.56 S m-1). Consequently, these conductive hydrogels exhibit strain-sensing properties with a significant increase in gauge factor (GF) of 14.6, covering an extensive detection range of ~ 1000%, fast response (198 ms) and exceptional cycle stability. These multifunctional hydrogels can be seamlessly integrated into motion detection sensors capable of distinguishing between various strong or subtle movements of the human body.

Controlled nanoparticle synthesis of Ag/Fe co-doped hydroxyapatite system for cancer cell treatment.

Diagnosis of cancer by chemotherapy treatment, severe side effects caused by high dosages of cancer drugs include non-controlled cytotoxicity to bone marrow cells and immune cells. To overcome, we have synthesized nanoparticles with controlled sized hydroxyapatite (nHAp) materials doped and co-doped with silver and iron by co-precipitation, yielding materials that can treat both the infections and malignant tumors with non-cytotoxic nature to normal cells. Spherical and rod like morphologies were observed for the samples with higher Ag+ doping concentrations with average size of 50 ±â€¯5 nm and (75 × 22) ±â€¯5 nm2, whereas higher Ag+/Fe2+ co-doping concentrations yielded samples with spherical, rod-like, and flake-like structures. For samples nHAp and Ag+-nHAp samples were diamagnetic, whereas the Fe2+-nHAp and Ag+/Fe2+ co-doped samples were superparamagnetic. The in vitro biological toxicity study revealed that the Ag+/Fe2+-nHAp nanoparticles are effective for targeting to kill cancerous cells, for example, human cervical cancer (HeLa) cells efficiently while they are non-toxic to normal cells. Applying these nanoparticles for drug delivery system, 5-fluorouracil was loaded in the nanoparticles and studied its release kinetics. In the case of Ag+/Fe2+co-doped nHAp samples, a pulsatile drug release profile was observed, which the drug was released for about a week on varying the Ag+ and Fe2+ concentrations. The 5-fluorouracil release kinetics was well fitted by the first-order model with diffusion. Thus, nHAps co-doped with Ag+/Fe2+ material have the potential to lag the time on delivering the drug at site-specific could be with an application in biomedicine such as to treat malignant tumor without any bacterial side effect.

Retraction Note: Fabrication of a microfluidic device for studying the in situ drug-loading/release behavior of graphene oxide-encapsulated hydrogel beads.

[This retracts the article DOI: 10.1186/s40824-018-0119-9.].

Fabrication of a microfluidic device for studying the in situ drug-loading/release behavior of graphene oxide-encapsulated hydrogel beads.

BACKGROUND: Controlled drug delivery system is highly important for not only prolonged the efficacy of drug but also cellular development for tissue engineering. A number of biopolymer composites and nanostructured carriers behave been used for the controlled drug delivery of therapeutics. Recently, in vitro microfluidic devices that mimic the human body have been developed for drug-delivery applications. METHODS: A microfluidic channel was fabricated via a two-step process: (i) polydimethyl siloxane (PDMS) and curing agent were poured with a 10:2 mass ratio onto an acrylic mold with two steel pipes, and (ii) calcium alginate beads were synthesized using sodium alginate and calcium chloride solutions. Different amounts (10, 25, 50 µg) of graphene oxide (GO) were then added by Hummers method, and studies on the encapsulation and release of the model drug, risedronate (Ris), were performed using control hydrogel beads (pH 6.3), GO-containing beads (10GO, 25GO and 50GO), and different pH conditions. MC3T3 osteoblastic cells were cultured in a microchannel with Ris-loaded GO-hydrogel beads, and their proliferation, viability, attachment and spreading were assessed for a week. RESULTS: The spongy and textured morphology of pristine hydrogel beads was converted to flowery and rod-shaped structures in drug-loaded hydrogel beads at reduced pH (6.3) and at a lower concentration (10 µg) of GO. These latter 10GO drug-loaded beads rapidly released their cargo owing to the calcium phosphate deposited on the surface. Notably, beads containing a higher amount of GO (50GO) exhibited an extended drug-release profile. We further found that MC3T3 cells proliferated continuously in vitro in the microfluidic channel containing the GO-hydrogel system. MTT and live/dead assays showed similar proliferative potential of MC3T3 cells. Therefore, a microfluidic device with microchannels containing hydrogel beads formulated with different amounts of GO and tested under various pH conditions could be a promising system for controlled drug release. CONCLUSIONS: The GO and drug (risedronate, Rig) were directed loaded into a hydrogel placed in a microchannel. Through interactions such as hydrogen bonding between Go and the Rig-loaded GO-hydrogel beads, the bead-loaded microfluidic device supported MC3T3 proliferation and development as osteoblast without additional osteogenic differentiation supplements.

Graphene Oxide-A Tool for the Preparation of Chemically Crosslinking Free Alginate-Chitosan-Collagen Scaffolds for Bone Tissue Engineering.

Developing a biodegradable scaffold remains a major challenge in bone tissue engineering. This study was aimed at developing novel alginate-chitosan-collagen (SA-CS-Col)-based composite scaffolds consisting of graphene oxide (GO) to enrich porous structures, elicited by the freeze-drying technique. To characterize porosity, water absorption, and compressive modulus, GO scaffolds (SA-CS-Col-GO) were prepared with and without Ca2+-mediated crosslinking (chemical crosslinking) and analyzed using Raman, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy techniques. The incorporation of GO into the SA-CS-Col matrix increased both crosslinking density as indicated by the reduction of crystalline peaks in the XRD patterns and polyelectrolyte ion complex as confirmed by FTIR. GO scaffolds showed increased mechanical properties which were further increased for chemically crosslinked scaffolds. All scaffolds exhibited interconnected pores of 10-250 µm range. By increasing the crosslinking density with Ca2+, a decrease in the porosity/swelling ratio was observed. Moreover, the SA-CS-Col-GO scaffold with or without chemical crosslinking was more stable as compared to SA-CS or SA-CS-Col scaffolds when placed in aqueous solution. To perform in vitro biochemical studies, mouse osteoblast cells were grown on various scaffolds and evaluated for cell proliferation by using MTT assay and mineralization and differentiation by alizarin red S staining. These measurements showed a significant increase for cells attached to the SA-CS-Col-GO scaffold compared to SA-CS or SA-CS-Col composites. However, chemical crosslinking of SA-CS-Col-GO showed no effect on the osteogenic ability of osteoblasts. These studies indicate the potential use of GO to prepare free SA-CS-Col scaffolds with preserved porous structure with elongated Col fibrils and that these composites, which are biocompatible and stable in a biological medium, could be used for application in engineering bone tissues.