Brucellae are Gram-negative, aerobic, non-motile coccobacilli causing brucellosis in man and animals. The disease is one of the most significant yet neglected global zoonoses. Especially in developing countries, brucellosis is causing public health problems and economic losses to private animal owners and national revenues. Composed of oligonucleotides, aptamers are chemical analogues of antibodies that are promising components for developing aptamer-based rapid, sensitive, and specific tests to identify the Brucella group of bacteria. For this purpose, aptamers were generated and selected by an enhanced protocol of cell systematic evolution of ligands by exponential enrichment (cell-SELEX). This enhanced cell-SELEX procedure involved the combination of both conventional and toggle cell-SELEX to boost the specificity and binding affinity to whole Brucella cells. This procedure, combined with high-throughput sequencing of the resulting aptamer pools, comprehensive bioinformatics analysis, and wet lab validation assays, led to the selection of a highly sensitive and specific aptamer for those Brucella species known to circulate in Egypt. The isolated candidate aptamer showed dissociation constant (K_D) values of 43.5 ± 11, 61.5 ± 8, and 56 ± 10.8 nM for B. melitensis, B. abortus, and B. suis, respectively. This is the first development of a Brucella-specific aptamer using an enhanced combination of conventional and toggle cell-SELEX to the authors’ best knowledge.

Breast cancer remains a challenging health issue, demanding innovative treatment approaches that maximize efficacy while minimizing damage to healthy cells. Targeted therapy offers a promising strategy tailored to the unique characteristics of breast cancer tumors. Gold nanoparticles have been studied in the context of their therapeutic potential towards cancer treatment showing great success. Recently, aptamers were also investigated for their targeting efficiency towards specific receptors allowing their use in targeting delivery systems. In this study, computational analysis was used to confirm the strong binding between AS1411 aptamer and the nucleolin receptor extensively present on the surface of breast cancer cells, highlighting the aptamer’s potential for specific targeting. Furthermore, we investigated and compared the use of AS1411 aptamer-conjugated chemically synthesized (GNPs) and flaxseed-green-synthesized (Fs-GNPs) gold nanoparticles as targeting therapeutic systems for breast cancer cells. Our results showed successful conjugation of the AS1411 aptamer with both, the GNPs and Fs-GNPs. Characterization of the nanoparticles and their conjugates validates their size, charge, and morphology, affirming the success of the conjugation process. Cytotoxicity assessments using the MTT assay demonstrated the effectiveness of the conjugates against breast cancer cells, with the AS1411-Fs-GNPs conjugate exhibiting higher inhibitory efficacy, featuring an IC₅₀ value of 11.13 µg/ml. In contrast, they showed minimal effect on normal cells, emphasizing the selectivity and potential safety of these therapies. To our knowledge, this is the first report of conjugating AS1411 aptamer to green-synthesized gold nanoparticles and its use as a targeting therapeutic system.

Nano-biotechnology has been a noticeable research area because of its successful applications in molecular diagnostics and therapy of various genetic and microbial diseases. Although the polymerase chain reaction (PCR) technique is one of the most highlighted and promising applications in the molecular diagnosis field, it suffers from some drawbacks that affect its efficiency. For instance, as a diagnostic technique for equine herpes virus-1 (EHV-1), conventional PCR could lead to false negative results due to the low viral titer in some samples, which leads to the necessity to improve its sensitivity. In this study, we carried out experiments to determine the effects of 15 nm unmodified citrate-coated gold nanoparticles (GNPs) on the key PCR reactants in order to see if these would enhance the overall outcomes of the reaction. Our results showed that, after optimization of the GNPs, oligonucleotide primers and Taq polymerase concentrations, a specific high yield amplification with a detection limit of 10² DNA copies could be reached compared to the 10⁵ to 10⁴ detection limit of conventional PCR. Thus, the developed and optimized GNPs-assisted PCR technique could be used for a more efficient, highly sensitive molecular detection of EHV-1.

Lumpy Skin Disease (LSD) is a notifiable viral disease caused by Lumpy Skin Disease virus (LSDV). It is usually associated with high economic losses, including a loss of productivity, infertility, and death. LSDV shares genetic and antigenic similarities with Sheep pox virus (SPV) and Goat pox (GPV) virus. Hence, the LSDV traditional diagnostic tools faced many limitations regarding sensitivity, specificity, and cross-reactivity. Herein, we fabricated a paper-based turn-on fluorescent Molecularly Imprinted Polymer (MIP) sensor for the rapid detection of LSDV. The LSDV-MIPs sensor showed strong fluorescent intensity signal enhancement in response to the presence of the virus within minutes. Our sensor showed a limit of detection of 10¹ log₁₀ TCID50/mL. Moreover, it showed significantly higher specificity to LSDV relative to other viruses, especially SPV. To our knowledge, this is the first record of a paper-based rapid detection test for LSDV depending on fluorescent turn-on behavior.

Selenium nanoparticles (SeNPs) and SeNPs conjugated with lysozyme (SeNPs-lysozyme) were synthesized via sodium selenite reduction with ascorbic acid and polysorbate-80 stabilization. These were physiochemically characterized to impart antibacterial properties. X-ray diffraction analysis (XRD) revealed that both formulations had hexagonal crystalline structures. Fourier transform infrared (FT-IR) confirmed the successful conjugation of lysozyme to SeNPs through the emergence of amine peaks at 1542 cm⁻¹. Dynamic light scattering (DLS) showed lysozyme conjugation increased nanoparticle size from 76.6 to 92.4 nm and charge from − 12.6 to + 17.6 mV. Transmission electron microscopy (TEM) images confirmed that spherical morphologies and size increased from 73–79 nm for SeNPs to 84–98 nm for SeNPs-lysozyme after lysozyme capping. Both formulations exhibited identical minimum inhibitory concentrations (MIC) of 125 μg/mL. However, lysozyme conjugation reduced SeNPs cytotoxicity by 2.4-fold based on IC₅₀ values from an MTT (Thiazolyl Blue Tetrazolium Bromide) assay. When tested in phosphate-buffered saline (PBS), SeNPs and SeNPs-lysozyme fully inhibited Bacillus cereus (B. cereus) proliferation up to 6 log₁₀ CFU/mL inoculums over 24 h of incubation. However, at (7 log₁₀ CFU/mL) inoculum, only partial inhibition occurred, with (2.5 ± 0.3 log₁₀ CFU/mL) growth still detected for SeNPs and (2.2 ± 0.2 log₁₀ CFU/mL) for SeNPs-lysozyme. At all inoculum levels (5, 6, and 7) log₁₀ CFU/mL, B. cereus grew a lot in milk (more than 8 log₁₀ CFU/mL). This was probably because SeNPs or SeNPs-lysozyme tend to aggregate around milk components, making them less effective.