There is increasing interest in the use of nanoparticles (NPs) for biomedical applications. In particular, nanobiophotonic approaches using fluorescence offers the potential of high sensitivity and selectivity in applications such as cell imaging and intracellular sensing. In this review, we focus primarily on the use of fluorescent silica NPs for these applications and, in so doing, aim to enhance and complement the key recent review articles on these topics. We summarize the main synthetic approaches, namely the Stöber and microemulsion processes, and, in this context, we deal with issues in relation to both covalent and physical incorporation of different types of dyes in the particles. The important issue of NP functionalization for conjugation to biomolecules is discussed and strategies published in the recent literature are highlighted and evaluated. We cite recent examples of the use of fluorescent silica NPs for cell imaging in the areas of cancer, stem cell and infectious disease research, and we review the current literature on the use of silica NPs for intracellular sensing of oxygen, pH and ionic species. We include a short final section which seeks to identify the main challenges and obstacles in relation to the potential widespread use of these particles for in vivo diagnostics and therapeutics.

Mobilization of stem cells in acute MI might signify the reparatory response. Aim of the Study. Prospective evaluation of correlation between CD34+CXCR4+ cell mobilization and improvement of LVEF and remodeling in patients with acute MI in 1-year followup. Methods. 50 patients with MI, 28 with stable angina (SAP), and 20 individuals with no CAD (CTRL). CD34+CXCR4+ cells, SDF-1, G-CSF, troponin I (TnI) and NT-proBNP were measured on admission and 1 year after MI. Echocardiography and ergospirometry were carried out after 1 year. Results. Number of CD34+CXCR4+ cells in acute MI was significantly higher in comparison with SAP and CTRL, but lower in patients with decreased LVEF ≤40%. In patients who had significant LVEF increase ≥5% in 1 year FU the number of cells in acute MI was significantly higher versus patients with no LVEF improvement. Number of cells was positively correlated (r = 0,41, P = 0,031) with absolute LVEF change and inversely with absolute change of ESD and EDD in 1-year FU. Mobilization of CD34+CXCR4+ cells in acute MI was negatively correlated with maximum TnI and NT-proBNP levels. Conclusion. Mobilization of CD34+CXCR4+ cells in acute MI shows significant positive correlation with improvement of LVEF after 1 year.

Frank Kjeldsen (2019) Silver nanoparticle-induced expression of proteins related to oxidative stress and neurodegeneration in an invitro human blood-brain barrier model,

An in-depth understanding of biochemical processes occurring within biological systems is key for early diagnosis of disease and identification of appropriate treatments. Nanobiophotonics offers huge potential benefits for intracellular diagnostics and therapeutics. Intracellular sensing using fluorescent nanoparticles is a potentially useful tool for real-time, in vivo monitoring of important cellular analytes. This work is focused on synthesis of optical chemical nanosensors for the quantitative analysis of pH inside living cells. The structure of the nanosensor comprises a biofriendly silica matrix with co-encapsulated Texas Red, acting as a reference dye, and pH-sensitive fluorescein isothiocyanate enabling ratiometric quantitative environmental detection. In order to obtain silica-based nanoparticles -70 nm in size, a modified sol-gel-based Stöber method was employed. The potential of these nanosensors for intracellular pH monitoring is demonstrated inside a live human embryonic kidney cell line whereby a significant change in fluorescence is observed when the cell pH is switched from acidic to basic. High loading efficiencies of nanoparticles into the cells is seen, with little effect on cell morphology even following extended nanoparticle exposure (up to 72 h). Nanoparticle incubation time and the fast response of the nanosensor (-2 s) make it a very powerful tool in monitoring the processes occurring within the cytosol.

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