Fabio Di Nardo

Lithium is increasingly recognized as a strategic resource due to its essential role in lithium-ion batteries. The high demand for lithium is rapidly depleting these resources, making efficient recovery methods essential. Ion-imprinted polymers (IIPs) have emerged as a promising solution for this challenge. This study focuses on the innovative use of polyethylene glycol diacrylate (PEGDA) as both a crosslinker and functional monomer for synthesis of lithium-ion imprinted polymers (Li-IIP) based on the formation of pseudo-crown ether structures thanks to the template effect of the Li+ ions, providing an efficient and cheap alternative to the use of expensive crown ethers. The optimal Li-IIP formulation was identified with a PEGDA-575 to lithium molar ratio of 2:1, prepared in DMSO, with an equilibrium binding constant of 20.1 ± 4.5 x 103 mol L-1, an imprinting factor of 33.5, and a good selectivity towards Li+ ions respect to Na+, K+, Co2+, Ni2+ and Mn2+ ions of 0.17, 0, 0.42, 0.39 and 0.17, respectively. Additionally, the use of sodium carbonate as a leaching agent enhanced the binding capacity of the polymer to 0.18 mmol g-1 (1.25 mg g-1) offering a convenient alternative to traditional acidic leaching methods. Overall, these findings highlight the promising potential of PEGDA-based Li-IIPs to develop cheap and sustainable lithium recovery processes

Adenosine is a low molecular weight purine nucleoside whose immunoassay development is complicated by limited immunogenicity and by the close structural similarity among nucleosides and nucleotides. Here, we report a microplate-compatible competitive biomimetic immunoassay in which adenosine-imprinted nanoMIPs replace antibodies as the molecular recognition element. Four template-immobilization strategies were compared to define how template orientation affects imprinting efficiency. Direct immobilization through selective 2′,3′-ribose oxidation, which leaves the adenine base exposed during polymerization, produced the most effective binding sites; incorporation of an adenine-complementary 1-(vinylbenzyl)thymine monomer further increased the apparent equilibrium binding constant to 3.2 × 10⁵ L mol⁻¹. The selected nanoMIPs were implemented in a two-step competitive format in which free adenosine competes with a 5′-biotinylated polyadenine oligonucleotide for the imprinted sites, whereas signal generation is performed separately through streptavidin-horseradish peroxidase. Under optimized conditions, the assay provided a limit of detection of 2.3 ng mL⁻¹, a working range of 5-88 ng mL⁻¹, and an IC50 of 21.6 ± 0.05 ng mL⁻¹. Cross-reactivity (CR) experiments showed preferential recognition of adenine-containing compounds (CR values for ATP, AMP and guanosine were in the 20-48% range) whereas cytidine and thymidine did not produce measurable competition. By decoupling molecular competition from enzymatic signal generation, this work establishes a two-step nanoMIP assay architecture for adenosine and provides a transferable framework for translating synthetic receptors into antibody-free assays for challenging small-molecule targets.

Lithium is increasingly recognized as a strategic resource due to its essential role in lithium-ion batteries. The high demand for lithium is rapidly depleting these resources, making efficient recovery methods essential. Ion-imprinted polymers (IIPs) have emerged as a promising solution for this challenge. This study focuses on the innovative use of polyethylene glycol diacrylate (PEGDA) as both a crosslinker and functional monomer for synthesis of lithium-ion imprinted polymers (Li-IIP) based on the formation of pseudo-crown ether structures thanks to the template effect of the Li+ ions, providing an efficient and cheap alternative to the use of expensive crown ethers. The optimal Li-IIP formulation was identified with a PEGDA-575 to lithium molar ratio of 2:1, prepared in DMSO, with an equilibrium binding constant of 20.1 ± 4.5 x 10^3 mol L-1, an imprinting factor of 33.5, and a good selectivity towards Li+ ions respect to Na+, K+, Co2+, Ni2+ and Mn2+ ions of 0.17, 0, 0.42, 0.39 and 0.17, respectively. Additionally, the use of sodium carbonate as a leaching agent enhanced the binding capacity of the polymer to 0.18 mmol g-1 (1.25 mg g-1) offering a convenient alternative to traditional acidic leaching methods. Overall, these findings highlight the promising potential of PEGDA-based Li-IIPs to develop cheap and sustainable lithium recovery processes

The rapid detection of zinc in different aqueous matrices is very relevant. For example, a Zn²⁺ level above ca. 50 µM affects drinking water quality, while levels below ca. 25 µM in urine are related to higher probability of prostate cancer. Herein, a simple and rapid qualitative colorimetric sensor for the detection of zinc ions in aqueous samples is developed. The sensor exploits the reaction between 1,5-diphenylthiocarbazone and Zn²⁺ to form colored chelates whose color changes with increasing Zn²⁺ concentration. The chelating agent has been immobilized in a dried form on various cellulose- and synthetic-based materials to obtain a sensor that can be used for in situ analysis. The procedure to obtain the colorimetric device is easy and straightforward. Moreover, it requires neither specialized personnel to perform the analysis nor specialized personnel for the interpretation of the analytical results. The analysis requires only 20 µL of sample, and a reliable colorimetric output is obtained within 10 min and is stable up to 30 min. The sensor allows Zn²⁺ visual detection in drinking water and urine without any sample pre-treatment with excellent efficiency and repeatability. Considering the ability to distinguish between Zn²⁺ concentrations equal to 0.5 and 2× the cut-off level, the sensor showed sensitivity and specificity of 100% for fortified tap water analysis and 100% sensitivity and 88.9% specificity for urine samples. The almost-perfect concordance with the reference atomic absorption spectrometer and the 94.1% accuracy demonstrated the sensor’s excellent potential to be applied for selective qualitative Zn²⁺ detection in real-life situations.

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic compound produced by certain fungi (e.g., Aspergillus flavus and Aspergillus parasiticus). Rapid and ultra-sensitive detection methods for AFB1 in various commodities are in high demand. This study aimed to enhance the sensitivity of a competitive lateral flow immunoassay (LFIA) for AFB1 detection by leveraging a previously developed experimental design strategy, named 4S. This approach comprises four phases—START, SHIFT, SHARPEN, and STOP—and involves the analysis of two reference conditions: NEG (0 ng/mL AFB1) and POS (1 ng/mL AFB1). By generating and overlaying response surfaces, regions of optimal NEG signal and POS/NEG signal ratio (IC%) were identified. Four variables were optimized: two related to the labeled antibody (its concentration and antibody-to-label ratio) and two to the competitor antigen (its concentration and hapten-to-protein ratio). An initial design defined the parameter space, while three subsequent designs did not yield further improvements in sensitivity. A strong anti-correlation was observed between the IC% and competitor parameters. The optimized LFIA-1 exhibited enhanced sensitivity, achieving a limit of detection of 0.027 ng/mL compared to 0.1 ng/mL for the original device. Additionally, the amount of expensive antibody required for device fabrication was reduced by around a factor of four.

MicroRNAs (miRNAs), which circulate in the serum and plasma, play a role in several biological processes, and their levels in body fluids are associated with the pathogenesis of various diseases, including different types of cancer. For this reason, miRNAs are considered promising candidates as biomarkers for diagnostic purposes, enabling the early detection of pathological onset and monitoring drug responses during therapy. However, current methods for miRNA quantification, such as northern blotting, isothermal amplification, RT-PCR, microarrays, and next-generation sequencing, are limited by their reliance on centralized laboratories, high costs, and the need for specialized personnel. Consequently, the development of sensitive, simple, and one-step analytical techniques for miRNA detection is highly desirable, particularly given the importance of early diagnosis and prompt treatment in cases of cancer. Lateral flow assays (LFAs) are among the most attractive point-of-care (POC) devices for healthcare applications. These systems allow for the rapid and straightforward detection of analytes using low-cost setups that are accessible to a wide audience. This review focuses on LFA-based methods for detecting and quantifying miRNAs associated with the diagnosis of various cancers, with particular emphasis on sensitivity enhancements achieved through the application of different labels and detection systems. Early, non-invasive detection of these diseases through the quantification of tailored biomarkers can significantly reduce mortality, improve survival rates, and lower treatment costs.

Point-of-care diagnostic tests, such as lateral-flow immunoassay (LFIA), have emerged as a fast diagnostic tool in both human and veterinary medicine. In this paper, a gold nanoparticle-based LFIA device was developed for the measurement of C-reactive protein (CRP) in porcine saliva, using a monoclonal anti-porcine CRP antibody. The dilution ratio for the saliva samples was optimized at 1:5 with an assay buffer. The reaction time was optimized to 20 min, since this provided a positive signal with high CRP concentration saliva samples, but a negative result with an assay buffer or samples with a low CRP concentration. Linear results were observed when two samples with a high CRP concentration were serially diluted. Also, a linear relationship was observed with a validated quantitative method. The assay was precise when samples with high CRP concentration were measured five times in a single assay run. No overlap was observed when samples from healthy and diseased animals were analyzed. The LFIA allowed the detection of high CRP concentrations in porcine saliva samples. The intensity of the result was proportional to the CRP concentration obtained with the quantitative method, allowing for the possible use of the test for semiquantitative purposes.

Being able to obtain an objective and repeatable measurement of stress levels from a single subject represents a primary issue in animal welfare science, especially in relation to cattle farming. A potential solution has been recently identified in the determination of cortisol’s salivary levels: a non-invasive method strictly related to acute stress. The development of an on-field, easy-to-use method to perform the analysis is yet to be validated. In this study, we developed and tested the reliability of salivary cortisol as a marker for the evaluation of animal welfare. We aimed to develop an on-field use Lateral Flow Immunoassay (LFIA) for the evaluation of acute stress in bovines. The availability of this non-invasive diagnostic tool will facilitate monitoring of animal welfare. In the short term, this innovation is expected to assist farmers and veterinarians in performing a more objective evaluation of the animal’s acute stress levels. In the long term, the device could become a key-instrument for the EU’s growing necessity to better monitor and identify the potential stressor factors in animal farming.