Stainless steel electrochemical capacitive microneedle sensors for multiplexed simultaneous measurement of pH, nitrates, and phosphates

"Emerging technologies for detecting foodborne pathogens and spoilage microorganisms in milk: Ensuring safety and quality"

Foodborne and spoilage microorganisms pose significant challenges to both food safety and product integrity, particularly within the dairy industry. These microorganisms can adversely affect milk quality, safety, shelf life, and the overall sustainability of the dairy industry, making their detection a critical concern in food science. This review explores a range of emerging and innovative detection techniques, including molecular, immunological, and sensor-based methods, with a focus on their practical implementation in dairy microbiology. While culture-based methods remain the gold standard, they suffer from several limitations, including being time-consuming, labor-intensive, costly, and less effective at detecting non-culturable microorganisms. Recent advancements in rapid, high-throughput, and high-sensitivity detection technologies have transformed the ability to identify and control both foodborne pathogens and spoilage microorganisms in milk, offering superior accuracy, efficiency, and real-time monitoring capabilities. This review provides a comprehensive overview of cutting-edge microbial detection approaches in milk, highlighting the key characteristics of these emerging methods developed in recent years. Furthermore, global regulatory standards in milk microbiology among eight representative countries were comparatively analyzed to elucidate the current landscape of dairy microbiology regulatory frameworks. Our primary objective is to synthesize current scientific research to offer insights into the effectiveness, practicality, and industry adoption of these emerging detection technologies. We critically examine studies that have contributed to the development of rapid and accurate microbial detection methods, assessing their impact on food safety, quality assurance, and regulatory compliance. By consolidating and analyzing cutting-edge advancements in microbial detection, this review aims to contribute to ongoing efforts to strengthen both food safety and quality assurance in the dairy industry by integrating novel detection technologies into routine monitoring practices. We aim to provide a valuable resource for researchers, industry professionals, and policymakers, facilitating informed decision-making and promoting the adoption of effective microbial detection strategies from dairy farms to consumer products.

A high-performance reagent-less sensor based on copper(ii) phthalocyanines supported by multi-walled carbon nanotubes for phosphate detection

Phosphate concentration is an important indicator of water quality, specifically for eutrophication levels in the presence of algae. Several analytical techniques have been proposed for phosphate monitoring, and most of them are based on indirect methods. In this study, we propose a new reagent-less direct method for the electrochemical detection of phosphate in aqueous solutions. For this, carbon screen printed electrodes (CSPE) were modified with copper(ii)-phthalocyanines (CuPc) that offer excellent oxidoreduction and electrocatalytic properties, together with chemically modified multiwalled carbon nanotubes (MWCNTs) to enhance the electrocatalytic performance of the sensor. We implemented two detection methods, which are electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) to compare them. The developed sensor exhibits a remarkable detection limit of 1.15 μM in the range from 10 μM to 100 μM with voltammetry and 0.13 nM in the range from 0.001 μM to 100 μM with impedance, enabling accurate measurement of phosphate concentrations in water samples. Thus, EIS shows a better sensitivity towards phosphate reduction. Furthermore, the developed sensor shows good performance in the presence of possibly interfering species that usually coexist with phosphate ions, as well as the applicability of the sensor in real water samples (tap water and nutrient water from an aquaponic system) at a good recovery rate. The electrode's response is highly reproducible with a relative standard deviation lower than 10%.

Microneedle Patches-Integrated Transdermal Bioelectronics for Minimally Invasive Disease Theranostics

Wearable epidermal electronics with non- or minimally-invasive characteristics can collect, transduce, communicate, and interact with accessible physicochemical health indicators on the skin. However, due to the stratum corneum layer, rich information about body health is buried under the skin stratum corneum layer, for example, in the skin interstitial fluid. Microneedle patches are typically designed with arrays of special microsized needles of length within 1000 µm. Such characteristics potentially enable the access and sample of biomolecules under the skin or give therapeutical treatment painlessly and transdermally. Integrating microneedle patches with various electronics allows highly efficient transdermal bioelectronics, showing their great promise for biomedical and healthcare applications. This comprehensive review summarizes and highlights the recent progress on integrated transdermal bioelectronics based on microneedle patches. The design criteria and state-of-the-art fabrication techniques for such devices are initially discussed. Next, devices with different functions, including but not limited to health monitoring, drug delivery, and therapeutical treatment, are highlighted in detail. Finally, key issues associated with current technologies and future opportunities are elaborated to sort out the state of recent research, point out potential bottlenecks, and provide future research directions.

Unravelling the role of microneedles in drug delivery: Principle, perspectives, and practices

In recent year, the research of transdermal drug delivery systems has got substantial attention towards the development of microneedles (MNs). This shift has occurred due to multifaceted advantages of MNs as they can be utilized to deliver the drug deeper to the skin with minimal invasion, offer successful delivery of drugs and biomolecules that are susceptible to degradation in gastrointestinal tract (GIT), act as biosensors, and help in monitoring the level of biomarkers in the body. These can be fabricated into different types based on their applications as well as material for fabrication. Some of their types include solid MNs, hollow MNs, coated MNs, hydrogel forming MNs, and dissolving MNs. These MNs deliver the therapeutics via microchannels deeper into the skin. The coated and hollow MNs have been found successful. However, they suffer from poor drug loading and blocking of pores. In contrast, dissolving MNs offer high drug loading. These MNs have also been utilized to deliver vaccines and biologicals. They have also been used in cosmetics. The current review covers the different types of MNs, materials used in their fabrication, properties of MNs, and various case studies related to their role in delivering therapeutics, monitoring level of biomarkers/hormones in body such as insulin. Various patents and clinical trials related to MNs are also covered. Covered are the major bottlenecks associated with their clinical translation and potential future perspectives.

Development of electrochemical sensors for quick detection of environmental (soil and water) NPK ions

All over the world, technology is becoming more and more prevalent in agriculture. Different types of instruments are already being used in this sector. For the time being, every farmer is trying to produce more crops on a piece of land. Eventually, soil loses its nutrients; however, to grow more crops, farmers use more fertilizers without knowing the proper conditions of the soil in real time. To overcome this issue, many scientists have recently focused on developing electrochemical sensors to detect macronutrients, i.e., nitrogen (N), phosphorus (P), and potassium (K), in soil or water rapidly. In this review, we focus mainly on the recent developments in electrochemical sensors used for the detection of nutrients (NPK) in different types of samples. As it is outlined, the use of smart and portable electrochemical sensors can be helpful for the reduction of excess fertilizer and can play a vital role in maintaining suitable conditions in soils and water. We are optimistic that this review can guide researchers in the development of a portable and suitable NPK detection system for soil nutrients.

Metallic elements combine with herbal compounds upload in microneedles to promote wound healing: a review

Wound healing is a dynamic and complex restorative process, and traditional dressings reduce their therapeutic effectiveness due to the accumulation of drugs in the cuticle. As a novel drug delivery system, microneedles (MNs) can overcome the defect and deliver drugs to the deeper layers of the skin. As the core of the microneedle system, loaded drugs exert a significant influence on the therapeutic efficacy of MNs. Metallic elements and herbal compounds have been widely used in wound treatment for their ability to accelerate the healing process. Metallic elements primarily serve as antimicrobial agents and facilitate the enhancement of cell proliferation. Whereas various herbal compounds act on different targets in the inflammatory, proliferative, and remodeling phases of wound healing. The interaction between the two drugs forms nanoparticles (NPs) and metal-organic frameworks (MOFs), reducing the toxicity of the metallic elements and increasing the therapeutic effect. This article summarizes recent trends in the development of MNs made of metallic elements and herbal compounds for wound healing, describes their advantages in wound treatment, and provides a reference for the development of future MNs.

Wearable microneedle array-based sensor for transdermal monitoring of pH levels in interstitial fluid

Microneedle-based wearable sensors offer an alternative approach to traditional invasive blood-based health monitoring and disease diagnostics techniques. Instead of blood, microneedle-based sensors target the skin interstitial fluid (ISF), in which the biomarker type and concentration profile resemble the one found in the blood. However, unlike blood, interstitial fluid does not have the same pH-buffering capacity causing deviation of pH levels from the physiological range. Information about the skin ISF pH levels can be used as a biomarker for a wide range of pathophysiological conditions and as a marker for the calibration of a wearable sensor. The ISF pH can significantly affect the detection accuracy of other biomarkers as it influences enzyme activity, aptamer affinity, and antibody-antigen interaction. Herein, we report the fabrication of a high-density polymeric microneedle array-based (PMNA) sensing patch and its optimization for the potentiometric transdermal monitoring of pH levels in ISF. The wearable sensor utilizes a polyaniline-coated PMNA having a density of ∼10,000 microneedles per cm², containing individual microneedles with a height of ∼250 μm, and a tip diameter of ∼2 μm. To prevent interference from other body fluids like sweat, an insulating layer is deposited at the base of the PMNA. The wearable pH sensor operates from pH 4.0 to 8.6 with a sensitivity of 62.9 mV per pH unit and an accuracy of ±0.036 pH units. Furthermore, testing on a mouse demonstrates the ability of the PMNA to provide a real-time reading of the transdermal pH values. This microneedle-based system will significantly contribute to advancing transdermal wearable sensors technology, simplifying the fabrication process, and improving the cost-effectiveness of such devices.

Electrochemical Microneedles: Innovative Instruments in Health Care

As a significant part of drug therapy, the mode of drug transport has attracted worldwide attention. Efficient drug delivery methods not only markedly improve the drug absorption rate, but also reduce the risk of infection. Recently, microneedles have combined the advantages of subcutaneous injection administration and transdermal patch administration, which is not only painless, but also has high drug absorption efficiency. In addition, microneedle-based electrochemical sensors have unique capabilities for continuous health state monitoring, playing a crucial role in the real-time monitoring of various patient physiological indicators. Therefore, they are commonly applied in both laboratories and hospitals. There are a variety of reports regarding electrochemical microneedles; however, the comprehensive introduction of new electrochemical microneedles is still rare. Herein, significant work on electrochemical microneedles over the past two years is summarized, and the main challenges faced by electrochemical microneedles and future development directions are proposed.