Optical and spectroscopic properties of human whole blood and plasma with and without Y₂O₃ and Nd³⁺:Y₂O₃ nanoparticles

Tranexamic acid (class I drug) reduced and capped gold nanoparticles as a potential hemostatic agent with enhanced performance

External hemostatic agents play a crucial role in stabilizing an impaired process during pathological conditions. The idea is to stabilize thein vivosystem as soon as possible. This study uses a class I hemostatic drug tranexamic acid as a reducing and capping agent for synthesizing the gold nanoparticles (Tr-AuNPs). Being the synthetic analogue of lysine and a biologically inspired alkylamine molecule, the chemistry can be fine-tuned for stable material that can simultaneously target the intrinsic and extrinsic hemostatic pathway, making it promising for hemostatic applications. The Tr-AuNPs of hydrodynamic diameter ∼46 nm were synthesized and evaluated physio-chemically using various analytical techniques wherein they showed hemocompatibility and increased thrombus weight compared to the native drug. The decrease in prothrombin time (PT) and international normalized ratio supported by the dynamic thromboelastography (TEG) study indicates the prepared nano-conjugate's potential in reducing time for attaining hemostasis as compared to the native tranexamic acid drug. At a 9μg ml-1concentration, Tr-AuNPs had a procoagulant effect, shown by decreased reaction time (R) and coagulation time (K) with improvedαangle and MA. There was a significant increase in the rate of coagulationin vivoby Tr-AuNPs, i.e. (52 s) compared to the native tranexamic acid (360 s). Radiolabelling studies ascertained thein vivobiocompatibility (non-invasive distribution, residence, clearance, and stability) of the Tr-AuNPs. The short-term toxicity studies were conducted to establish a proof of concept for the biomedical application of the material. The results highlighted the use of biologically alkyl amine molecules as capping and reducing agents for the synthesis of nanoparticles, which have shown a synergistic effect on the coagulation cascade while holding the potential for also acting as potential theranostic agents.

Fluorescence emission quenching of RdB fluorophores in attendance of various blood type RBCs based on Stern-Volmer formalism

In this work, the optical properties of Rhodamine B (RdB) are investigated in the attendance of various red blood cells (RBCs). RdB fluorophores, as biological markers, is excited using SHG-CW Nd:YAG laser at 532 nm. In fact, the addition of biomolecules of interest to the reference fluorophore notably changes the fluorescence properties of the suspension. Here, laser induced fluorescence (LIF) spectrophotometry based on Stern-Volmer quenching formalism and field emission scanning electron microscope (FESEM) are employed here. According to the given fluorescence spectra, the spectral shift of emissions as well as quenching coefficients are assessed subsequently. The Stern-Volmer formalism is used to determine the quenching coefficients. In fact, RdB + RBCs suspensions contain a plenty of bioconjugates leading to the signal reduction and notable red shift in RdB fluorescence emissions. Furthermore, it is demonstrated that the positive blood type RBCs exhibit the higher quenching coefficients and the larger red shifts against those of negative blood types. This mainly arises from the nature of specific sugar antigens available on the RBC membranes as to N-acetylgalactosamine and galactose attached to the O-antigen terminal would enhance further quenching of the species. Moreover, a significant correlation appears between Stern-Volmer coefficients and the corresponding RBCs. In fact, distinct discrepancy takes place in quenching coefficients in terms various positive/negative blood types to envisage a facile method of blood typing.

Can "Indirect" Contact Laser Surgery be Used for Fluorescence-Image Guided Tumor Resections? Preliminary Results

Ensuring the complete removal of tumor tissue is the main challenge during resection operations. Recently, a technique of “indirect” contact laser surgery has been developed. In this study we assess the possibility of using such surgery for fluorescence image-guided tumor resection. Mouse colon adenocarcinoma CT-26 cells stably expressing the fluorescent protein mKate-2 was used as the tumor model. Resections of the tumor nodes were performed with either a scalpel blade, a laser scalpel with a bare tip, or a laser scalpel with a strongly absorbing coating on the fiber tip. Tumor-positive resection margins were detected using an IVIS Spectrum fluorescence imaging system. After tumor resection with the scalpel blade over half of the animals needed one additional resection to remove residual tumor cells. Animals in this group showed tumor recurrence within 7 days. Fluorescence imaging of the tumor bed, performed after resection to assess the presence of tumor cell clusters, was sufficiently effective only with a bloodless resection. The laser scalpels both with the bare tip and with the strongly absorbing coating on the tip provided such bloodless tumor resection in contact mode. Fewer animals required additional resections when the bare tipped scalpel was used and this also resulted in a reduction in tumor recurrence. After resections were carried out with the laser scalpel with the strongly absorbing coating on the tip, fluorescence was detected in the operative field and this led to undertaking additional resections, although subsequent investigation suggested that this was “false” fluorescence, resulting from the effects of the scalpel rather than the presence of residual tumor cells. The method of laser resection with a strongly absorbing coating on the tip therefore did not appear to demonstrate definite advantages over laser resection with a bare tip when removing tumors.

Focal photodynamic intracellular acidification as a cancer therapeutic

Cancer cells utilize an array of proton transporters to regulate intra- and extracellular pH to thrive in hypoxic conditions, and to increase tumor growth and metastasis. Efforts to target many of the transporters involved in cancer cell pH regulation have yielded promising results, however, many productive attempts to disrupt pH regulation appear to be non-specific to cancer cells, and more effective in some cancer cells than others. Following a review of the status of photodynamic cancer therapy, a novel light-activated process is presented which creates very focal, rapid, and significant decreases in only intracellular pH (pHi), leading to cell death. The light-activation of the H⁺ carrier, nitrobenzaldehyde, has been effective at initiating pH-induced apoptosis in non-cancerous and numerous cancerous cell lines in vitro, to include breast, prostate, and pancreatic cancers. Also, this intracellular acidification technique caused significant reductions in tumor growth rate and enhanced survival in mice bearing triple negative breast cancer tumors. The efficacy of an NBA-upconverting nanoparticle to kill breast cancer cells in vitro is described, as well as a discussion of the potential intracellular mechanisms underlying the pH-induced apoptosis.