No abstract

Properties of the hydroxyapatite obtained by electrochemical assisted deposition (ED) are dependent on several factors including deposition temperature, electrolyte pH and concentrations, applied potential. All of these factors directly influence the morphology, stoichiometry, crystallinity, electrochemical behaviour, and particularly the coating thickness. Coating structure together with surface micro- and nano-scale topography significantly influence early stages of the implant bio-integration. The aim of this study is to analyse the effect of pH modification on the morphology, corrosion behaviour and in vitro bioactivity and in vivo biocompatibility of hydroxyapatite prepared by ED on the additively manufactured Ti64 samples. The coatings prepared in the electrolytes with pH = 6 have predominantly needle like morphology with the dimensions in the nanometric scale (~30 nm). Samples coated at pH = 6 demonstrated higher protection efficiency against the corrosive attack as compared to the ones coated at pH = 5 (~93% against 89%). The in vitro bioactivity results indicated that both coatings have a greater capacity of biomineralization, compared to the uncoated Ti64. Somehow, the coating deposited at pH = 6 exhibited good corrosion behaviour and high biomineralization ability. In vivo subcutaneous implantation of the coated samples into the white rats for up to 21 days with following histological studies showed no serious inflammatory process.

One of the greatest challenges in neuro-oncology is diagnosis and therapy (theranostics) of leptomeningeal metastasis (LM), brain metastasis (BM) and brain tumors (BT), which are associated with poor prognosis in patients. Retrospective analyses suggest that cerebrospinal fluid (CSF) is one of the promising diagnostic targets because CSF passes through central nervous system, harvests tumor-related markers from brain tissue and, then, delivers them into peripheral parts of the human body where CSF can be sampled using minimally invasive and routine clinical procedure. However, limited sensitivity of the established clinical diagnostic cytology in vitro and MRI in vivo together with minimal therapeutic options do not provide patient care at early, potentially treatable, stages of LM, BM and BT. Novel technologies are in demand. This review outlines the advantages, limitations and clinical utility of emerging liquid biopsy in vitro and photoacoustic flow cytometry (PAFC) in vivo for assessment of CSF markers including circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), microRNA (miRNA), proteins, exosomes and emboli. The integration of in vitro and in vivo methods, PAFC-guided theranostics of single CTCs and targeted drug delivery are discussed as future perspectives.

A variety of biodegradable polymer scaffolds serving the purpose of mimicking the extracellular matrix have been studied; however, no effective recipe has yet been developed for scaffold pore size and overall percent porosity, which are optimal for cell penetration in vitro and tissue growth in vivo. Thus, this study reports the effect of poly(ε-caprolactone) (PCL) fiber size and scaffold porosity on the osteogenic behavior of scaffolds in a rat model in vivo. It was revealed that scaffolds with an average fiber size of 9.2 μm, and 4.05 μm, and combination of 0.6 μm submicrofibres (upper layer) with 9.2 μm microfibres (bottom layer) in hybrid two-layer scaffolds behave significantly differently with respect to macrophage reactions and tissue regeneration in a rat model in vivo. Poor macrophage response at implantation tests into the bone tissue in vivo reveals the advantages of microfibrous PCL scaffolds with a fiber size of 4.05 μm and hybrid scaffolds with submicro-and microfibres for stimulation of reparative osteogenesis over microfibrous scaffolds with a fiber size of 9.2 μm. The combination of submicro-and microfibrous layers in hybrid scaffolds provides an opportunity to control the shape and density of bone trabeculae during regeneration processes in vivo.