The bactericidal effects of silver nanoparticles (Ag NPs) against infectious strains of multiresistant bacteria is a well-studied phenomenon, highly relevant for many researchers and clinicians battling bacterial infections. However, little is known about the uptake of the Ag NPs into the bacteria, the related uptake mechanisms, and how they are connected to antimicrobial activity. Even less information is available on AgAu alloy NPs uptake. In this work, the interactions between colloidal silver-gold alloy nanoparticles (AgAu NPs) and Staphylococcus aureus (S. aureus) using advanced electron microscopy methods are studied. The localization of the nanoparticles is monitored on the membrane and inside the bacterial cells and the elemental compositions of intra- and extracellular nanoparticle species. The findings reveal the formation of pure silver nanoparticles with diameters smaller than 10 nm inside the bacteria, even though those particles are not present in the original colloid. This finding is explained by a local RElease PEnetration Reduction (REPER) mechanism of silver cations emitted from the AgAu nanoparticles, emphasized by the localization of the AgAu nanoparticles on the bacterial membrane by aptamer targeting ligands. These findings can deepen the understanding of the antimicrobial effect of nanosilver, where the microbes are defusing the attacking silver ions via their reduction, and aid in the development of suitable therapeutic approaches.

Hormonal therapy plays a vital part in the treatment of estrogen receptor-positive (ER +) breast cancer. ER can be activated in a ligand-dependent and independent manner. Currently available ER-targeting agents include selective estrogen receptor modulators (SERMs), selective estrogen receptor degraders (SERDs), and aromatase inhibitors (AIs). Estrogen receptor mutation (ESR1 mutation) is one of the common mechanisms by which breast cancer becomes resistant to additional therapies from SERMs or AIs. These tumors remain sensitive to SERDs such as fulvestrant. Fulvestrant is limited in clinical utilization by its intramuscular formulation and once-monthly injection in large volumes. Oral SERDs are being rapidly developed to replace fulvestrant with the potential of higher efficacy and lower toxicities. Elacestrant is the first oral SERD that went through a randomized phase III trial showing increased efficacy, especially in tumors bearing ESR1 mutation, and good tolerability. Two other oral SERDs recently failed to achieve the primary endpoints of longer progression-free survival (PFS). They targeted tumors previously treated with several lines of prior therapies untested for ESR1 mutation. Initial clinical trial data demonstrated that tumors without the ESR1 mutation are less likely to benefit from the SERDs and may still respond to SERMs or AIs, including tumors previously exposed to hormonal therapy. Testing for ESR1 mutation in ongoing clinical trials and in hormonal therapy for breast cancer is highly recommended. Novel protein degradation technologies such as proteolysis-targeting chimera (PROTACS), molecular glue degrader (MGD), and lysosome-targeting chimeras (LYTACS) may result in more efficient ER degradation, while ribonuclease-targeting chimeras (RIBOTAC) and small interfering RNA (siRNA) may inhibit the production of ER protein.

Short oligonucleotides are widely used for the construction of aptamer-based sensors and logical bioelements to modulate aptamer-ligand binding. However, relationships between the parameters (length, location of the complementary region) of oligonucleotides and their influence on aptamer-ligand interactions remain unclear. Here, we addressed this task by comparing the effects of short complementary oligonucleotides (ssDNAs) on the structure and ligand-binding ability of an aptamer and identifying ssDNAs\' features that determine these effects. Within this, the interactions between the OTA-specific G-quadruplex aptamer 1.12.2 (5\'-GATCGGGTGTGGGTGGCGTAAAGGGA GCATCGGACA-3\') and 21 single-stranded DNA (ssDNA) oligonucleotides complementary to different regions of the aptamer were studied. Two sets of aptamer-ssDNA dissociation constants were obtained in the absence and in the presence of OTA by isothermal calorimetry and fluorescence anisotropy, respectively. In both sets, the binding constants depend on the number of hydrogen bonds formed in the aptamer-ssDNA complex. The ssDNAs\' having more than 23 hydrogen bonds with the aptamer have a lower aptamer dissociation constant than for aptamer-OTA interactions. The ssDNAs\' having less than 18 hydrogen bonds did not affect the aptamer-OTA affinity. The location of ssDNA\'s complementary site in the aptamer affeced the kinetics of the interaction and retention of OTA-binding in aptamer-ssDNA complexes. The location of the ssDNA site in the aptamer G-quadruplex led to its unfolding. In the presence of OTA, the unfolding process was longer and takes from 20 to 70 min. The refolding in the presence of OTA was possible and depends on the length and location of the ssDNA\'s complementary site. The location of the ssDNA site in the tail region led to its rapid displacement and wasn\'t affecting the G-qaudruplex\'s integrity. It makes the tail region more perspective for the development of ssDNA-based tools using this aptamer.

Exosomal glycoproteins play important roles in many physiological and pathological functions. Herein, we developed a dual labeling strategy based on a protein-specific aptamer tagging and metabolic glycan labeling for visualizing glycosylation of specific proteins on exosomes. The glycosylation of exosomal PD-L1 (exoPD-L1) was imaged in situ using intramolecular fluorescence resonance energy transfer (FRET) between fluorescent PD-L1 aptamers bound on exoPD-L1 and fluorescent tags on glycans introduced via metabolic glycan labeling. This method enables in situ visualization and biological function study of exosomal protein glycosylation. Exosomal PD-L1 glycosylation was confirmed to be required in interaction with PD-1 and participated in inhibiting of CD8+ T cell proliferation. This is an efficient and non-destructive method to study the presence and function of exosomal protein-specific glycosylation in situ, which provides a powerful tool for exosomal glycoproteomics research.

Cancer is the most devastating disease in the present scenario, killing millions of people every year. Early detection, accurate diagnosis, and timely treatment are considered to be the most effective ways to control this disease. Rapid and efficient detection of cancer at their earliest stage is one of the most significant challenges in cancer detection and cure. Numerous diagnostic modules have been developed to detect cancer cells early. As nucleic acid equivalent to antibodies, aptamers emerge as a new class of molecular probes that can identify cancer-related biomarkers or circulating rare cancer/ tumor cells with very high specificity and sensitivity. The amalgamation of aptamers with the biosensing platforms gave birth to \"Aptasensors.\" The advent of highly sensitive aptasensors has opened up many new promising point-of-care diagnostics for cancer. This comprehensive review focuses on the newly developed aptasensors for cancer diagnostics.

The performance of aptamer-based biosensors is crucially impacted by their interactions with physiological metal ions, which can alter their structures and chemical properties. Therefore, elucidating the nature of these interactions carries the utmost importance in the robust design of highly efficient biosensors. We investigated Mg 2 + binding to varying sequences of polymers to capture the effects of ionic strength and grafting density on ion binding and molecular reorganization of the polymer layer. The polymers are modeled as ssDNA aptamers using a self-consistent field theory, which accounts for non-covalent ion binding by integrating experimentally-derived binding constants. Our model captures the typical polyelectrolyte behavior of chain collapse with increased ionic strength for the ssDNA chains at low grafting density and exhibits the well-known re-entrant phenomena of stretched chains with increased ionic strength at high grafting density. The binding results suggest that electrostatic attraction between the monomers and Mg 2 + plays the dominant role in defining the ion cloud around the ssDNA chains and generates a nearly-uniform ion distribution along the chains containing varying monomer sequences. These findings are in qualitative agreement with recent experimental results for Mg 2 + binding to surface-bound ssDNA.

Early identification of neoplastic diseases is essential to achieve timely therapeutic interventions and significantly reduce the mortality of patients. A well-known biomarker is the Cancer Antigen 125 (CA125) or 16 mucin (MUC 16), a glycoprotein of the human family of mucins, already used for the diagnostic and prognostic evaluation of ovarian cancer. Therefore, the detection of CA125 to now remains a promising tool in the early diagnosis of this tumor. In this paper, we describe the development of RNA aptamers that bind with high affinity the tumor antigen CA125. We performed eight cycles of selection against CA125 purified protein. The selected aptamers were cloned and sequenced and the binding properties of the most promising sequences were studied by Real Time PCR and Surface Plasmon Resonance (SPR) to evaluate their ability in targeting CA125 protein with perspective applications in aptamer-based bioassays.

Aptamers are an emerging class of molecules that, because of the development of the systematic evolution of ligands by exponential enrichment (SELEX) process, can recognize virtually every target ranging from ions, to proteins, and even whole cells. Although there are many techniques capable of detecting template molecules with aptamer-based systems with high specificity and selectivity, they lack the possibility of integrating them into a compact and portable biosensor setup. Therefore, we will present the heat-transfer method (HTM) as an interesting alternative because this offers detection in a fast and low-cost manner and has the possibility of performing experiments with a fully integrated device. This concept has been demonstrated for a variety of applications including DNA mutation analysis and screening of cancer cells. To the best our knowledge, this is the first report on HTM-based detection of proteins, in this case specifically with aptamer-type receptors. For proof-of-principle purposes, measurements will be performed with the peanut allergen Ara h 1 and results indicate detection limits in the lower nanomolar regime in buffer liquid. As a first proof-of-application, spiked Ara h 1 solutions will be studied in a food matrix of dissolved peanut butter. Reference experiments with the quartz-crystal microbalance will allow for an estimate of the areal density of aptamer molecules on the sensor-chip surface.

Guanine (G)-rich oligonucleotides have attracted considerable interest as therapeutic agents. Two G-rich aptamers were selected against epidermal growth factor receptor (EGFR)-transfected A549 cells, and their G-rich domains (S13 and S50) were identified to account for the binding of parental aptamers. Circular dichroism (CD) spectra showed that S13 and S50 bound to their targets by forming parallel quadruplexes. Their binding, internalization, and antiproliferation activity in cancer and noncancer cells were investigated by flow cytometry and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, and compared with those of nucleolin-binding AS1411 and thrombin-binding aptamer. The two truncated aptamers (S13 and S50) have good binding and internalization in cancer cells and noncancer cells; however, only S50, similar to AS1411, shows potent antiproliferation against cancer cells. Our data suggest that tumor-selective antiproliferation of G-rich oligonucleotides does not directly depend on the binding of the G-rich aptamer to cells.