Nanoindentation for Monitoring the Time-Variant Mechanical Strength of Drug-Loaded Collagen Hydrogel Regulated by Hydroxyapatite Nanoparticles

Abstract

Hydroxyapatite nanoparticle-complexed collagen (HAP/Col) hydrogels have been widely used in biomedical applications as a scaffold for controlled drug release (DR). The time-variant mechanical properties (Young’s modulus, E ) of HAP/Col hydrogels are highly relevant to the precise and efficient control of DR. However, the correlation between the DR and the E of hydrogels remains unclear because of the lack of a nondestructive and continuous measuring system. To reveal the correlations, herein, we investigate the time-variant behavior of E for HAP/Col hydrogels during 28 days using the atomic force microscopy (AFM) nanoindentation technique. The initial E of hydrogels was controlled from 200 to 9000 Pa by the addition of HAPs. Subsequently, we analyzed the relationship between the DR of the hydrogels and the changes in their mechanical properties (Δ E ) during hydrogel degradation. Interestingly, the higher the initial E value of HAP/Col hydrogels is, the higher is the rate of hydrogel degradation over time. However, the DR of hydrogels with higher initial E appeared to be significantly delayed by up to 40% at a maximum. The results indicate that adding an appropriate amount of HAPs into hydrogels plays a crucial role in determining the initial E and their degradation rate, which can contribute to the properties that prolong DR. Our findings may provide insights into designing hydrogels for biomedical applications such as bone regeneration and drug-delivery systems.

Natural bone-mimicking nanopore-incorporated hydroxyapatite scaffolds for enhanced bone tissue regeneration

“…However, both XRD and FTIR spectroscopy analyses indicated a phase transition from HAP to tricalcium phosphate (TCP) beyond the sintering temperature of 500 °C; a new peak appeared at 31.1° in the diffraction pattern and 1120 cm − 1 in the IR transmission spectrum (Fig. 3 c and d) [ 67 – 69 , 71 ]. As our study focused on the investigation of the effect of natural bone-mimicking nanopores in the HAP scaffold rather than the influence of the phase transition from HAP to TCP, SNPs sintered above 500 °C were not analyzed.…”

Colorimetric Nanoparticle-Embedded Hydrogels for a Biosensing Platform

“…Among them, NP-embedded hydrogel complexes have attracted considerable attention because of the advantages of hydrogels, such as biodegradability, biocompatibility and non-toxicity, which can be combined with the unique properties of NPs [ 12 , 13 , 14 , 15 , 16 ]. For example, Jung et al demonstrated that the mechanical properties of a collagen hydrogel could be modulated by adding hydroxyapatite NPs [ 17 ]. Arno et al demonstrated improved adhesion and resistance to breakage in calcium alginate hydrogels using poly( L -lactide)-based NPs [ 18 ].…”

Melanoma Detection by AFM Indentation of Histological Specimens

“…Atomic force microscopy (AFM) is a multi-functional device that can analyze a sample’s morphology, mechanical strength, and surface charge by its nano-scale cantilever [ 36 , 37 , 38 , 39 ]. In this report, we demonstrate a robust mechanical characterization of histological specimens using atomic force microscopy (AFM) indentation for discrimination among normal, benign nevus, and melanoma.…”

“…As such, our goals were to verify (i) whether the mechanical characterization of the histological specimen would be consistent with the results from conventional histopathological analysis and (ii) whether it could provide abundant information about benign versus malignant epidermal tissues, complementing the traditional histopathological examinations. Atomic force microscopy (AFM) is a multi-functional device that can analyze a sample's morphology, mechanical strength, and surface charge by its nano-scale cantilever [36][37][38][39]. In this report, we demonstrate a robust mechanical characterization of histological specimens using atomic force microscopy (AFM) indentation for discrimination among normal, benign nevus, and melanoma.…”