Neutral pH monosaccharide receptor based on boronic acid decorated poly(2-hydroxyethyl methacrylate): Spectral Methods for determination of glucose-binding and ionization constants

Achieving enhanced stabilization and controlled release of curcumin via cross-linked polydopamine particles

Development of efficient drug delivery systems remains a critical challenge in pharmaceutical applications, necessitating novel approaches to improve drug loading and release profiles. In this study, a novel method is presented for fabricating crosslinked polydopamine particles (XPDPs) using a water/water Pickering emulsion system. The emulsion is composed of poly(ethylene glycol) and dextran, stabilized by polydopamine (PDA) particles. This method yields XPDPs with a mean particle size of 0.55 μm, significantly smaller than PDA particles (1.025 μm), resulting in a higher surface area favorable for drug loading. The adsorption mechanism involves electron sharing and covalent bonding between the carrier and drug molecules. The adsorption, release, and drug delivery kinetics of the XPDPs are compared with those of the non-crosslinked PDA particles. The results demonstrate that XPDPs exhibit improved adsorption properties due to their crosslinked structure and increased positive charge due to presence of secondary amines. During a 28-h period, curcumin release from PDA declines from around 80 %-40 %, while for XPDA, it decreases from approximately 60 %-35 % as the pH shifts from 7.4 to 5. While PDA particles display a burst release profile, XPDPs show a more gradual and sustained release, attributed to their enhanced structural stability. Molecular simulations were conducted to estimate the solubility parameters, confirming the compatibility between PDA and dextran for effective drug loading.

Coumarin-Modified Starch Fluorescent Nanoparticles as Sensor of Fe3+ and Zn2+ ions Utilizing Dynamic Quenching and Chelation Mechanisms

Zinc and iron are two essential trace minerals that play a pivotal role in maintaining optimal health and well-being in the human body. Despite being required in relatively small quantities, their significance can be understated as they participate in a wide array of critical physiological processes such as oxygen transport, DNA synthesis, controlling nutrient availability, etc. Understanding the distribution and behavior of these ions in natural water bodies is essential for assessing water quality, studying ecological processes, and managing environmental impacts. In this study, we have developed a dual fluorescence probe using starch which was functionalized with coumarin derivatives, for efficient detection of Fe3+ and Zn2+ ions. This structure led a self-assembled starch/coumarin (SC) fluorescent nanoparticles with strong fluorescence intensity under ultraviolet light (365 nm). The quenching effect of Fe3+ on the SC fluorescent probe enabled efficient specific detection of Fe3+. Furthermore, Zn2+ ions increased fluorescence intensity of coumarin compounds (λemission = 459). This phenomenon occurs when the coumarin compound forms a complex or interacts with the zinc ion, resulting in enhanced fluorescence emission. In summary, the developed fluorescent probe offered a promising approach for sensitive and specific detection of iron and zinc ions in aqueous solutions.

Transdermal Insulin Delivery and Microneedles-based Minimally Invasive Delivery Systems

Diabetes has become a serious threat to human health, causing death and pain to numerous patients. Transdermal insulin delivery is a substitute for traditional insulin injection to avoid pain from the injection. Transdermal methods include non-invasive and invasive methods. As the non-invasive methods could hardly get through the stratum corneum, minimally invasive devices, especially microneedles, could enhance the transappendageal route in transcutaneous insulin delivery, and could act as connectors between the tissue and outer environment or devices. Microneedle patches have been in quick development in recent years and with different types, materials and functions. In those patches, the smart microneedle patch could perform as a sensor and reactor responding to glucose to regulate the blood level. In the smart microneedles field, the phenylboronic acid system and the glucose oxidase system have been successfully applied on the microneedle platform. Insulin transdermal delivery strategy, microneedles technology and smart microneedles' development would be discussed in this review.

A new fluorescent boronic acid sensor based on carbazole for glucose sensing via aggregation-induced emission

A water-soluble fluorescent sensor based on carbazole pyridinium boronic acid (CPBA) was designed and synthesized. Its structure has been confirmed by CHN and 1H and 13C NMR, FT-IR, and MS spectral data. Fluorescence studies of the synthesized chemosensor CPBA showed a selective ratiometric fluorescent response for glucose among different monosaccharides. The results specified that CPBA is a pH-sensitive sensor that behaves differently in the absence and presence of glucose in the pH range 4-10. The pH, DLS, Job's plot, UV-visible, and fluorescence titration studies showed that the selectivity of CPBA towards glucose is through the aggregation-induced emission (AIE) phenomenon. The fluorescence emission intensity of CPBA changes by more than 2100 fold by adding glucose, whereas it is 2 fold for fructose. The calculated binding constant value of CPBA for glucose (K = 2.3 × 106 M-1) is 85 times greater than for fructose, indicating the high affinity of the sensor for glucose.

Investigation of interaction between boronic acids and sugar: effect of structural change of sugars on binding affinity using steady state and time resolved fluorescence spectroscopy and molecular docking

Binding interactions of boronic acid derivatives viz. 2-Methylphenylboronic acid (B1) and 3-Methoxyphenylboronic acid (B2) with mono saccharides (arabinose, fructose and galactose) and disaccharides (sucrose, lactose and maltose) in aqueous condition at pH 7.4 by means of fluorescence spectroscopy is reported in the present investigation. Sugar sensing as well as continuous glucose monitoring (CGM) plays a significant role in diabetes regulation. Sugar sensors mediated through enzymes have their own drawbacks, which led to encouragement to search for designing new sensors through alternate approaches. Among many, fluorescence-based sensors are drawing more attention. Boronic acid-based fluorescence sensors have the capacity to bind reversibly with diols, which makes their demand high in applications. Addition of sugar reduces fluorescence intensities. Change in intensities is associated to cleavage of intermolecular hydrogen bonding which leads in reduced stability of boronate ester. Lineweaver-Burk and Benesi-Hildebrand equation is used for analysing data. Mono sugars are estimated to have higher binding constants. Mutarotation leads to structural changes in saccharides which play a key role in binding interactions. Sugars in furanose form are found to be highly favoured for binding. Molecular docking of B1 and B2 with proteins with PDB ID: 2IPL and 2IPM being periplasmic was done with the help of Schrodinger Maestro 11.2 version. GLIDE scores terms are used for expressing binding affinity.

Understanding the binding interaction between phenyl boronic acid P1 and sugars: determination of association and dissociation constants using S-V plots, steady-state spectroscopic methods and molecular docking

Continuous monitoring of glucose and sugar sensing plays a vital role in diabetes control. The drawbacks of the present enzyme-based sugar sensors have encouraged the investigation into alternate approaches to design new sensors. The popularity of fluorescence sensors is due to their ability to bind reversibly to compounds containing diol. In this study we investigated the binding ability of phenyl boronic acid P1 for monosaccharides and disaccharides (sugars) in aqueous medium at physiological pH 7.4 using steady-state fluorescence and absorbance. P1 fluorescence was quenched due to formation of esters with sugars. Absorbance and fluorescence measurements led to results that indicated that the sugars studied could be ordered in terms of their affinity to P1, as stated: sucrose > lactose > galactose > xylose > ribose > arabinose. In each case, the slope of modified Stern-Volmer plots was nearly 1, indicating the presence of only a single binding site in boronic acids for sugars. Docking studies were carried out using Schrodinger Maestro v.11.2 software. The binding affinity of phenyl boronic acid P1 with periplasmic protein (PDB ID 2IPM and 2IPL) was estimated using GlideScore.