A Pseudopolyrotaxane for Glucose-Responsive Insulin Release: The Effect of Binding Ability and Spatial Arrangement of Phenylboronic Acid Group

FT-IR, FT-raman and UV spectra and ab initio HF and DFT study of conformational analysis, molecular structure and properties of ortho- meta- and para-chlorophenylboronic acid isomers

In this study, the FT-IR, FT-Raman, and UV-Vis spectroscopic properties of three monosubstituted phenylboronic acid derivatives: ortho-chlorophenylboronic acid (o-ClPhBA), meta-chlorophenylboronic acid (m-ClPhBA) and para-chlorophenylboronic acid (p-ClPhBA) molecules are investigated both experimentally and theoretically using Density Functional Theory (B3LYP) and Hartree Fock (HF). In order to find the stable possible conformations of the compounds, the conformational analysis was carried out by running potential energy surface (PES) scan by means of rotation of two structural parameters, the dihedral angles indicated as φ2 (C6-B-O1-H1A) and φ3 (C6-B-O2-H2A), varying from -180° to 180° with an increment of 10° using B3LYP/6-31G level of theory. Also, to determinate the most stable conformer for all the molecules, potential energy curve (PEC) the stable possible conformations on PES scan were investigated as a function of φ1 (C1-C6-B-O1) dihedral angle from 0° up to 180° with an increment of 10° using B3LYP/6-311++G(d,p) and HF/6-311++G(d,p) level of theory. For all the studied compounds, two conformational structures (conformer anti-anti, syn-syn) that did not have imaginary frequency values outside the equilibrium state (conformer anti-syn) were detected theoretically at the both methods. Due to their conformational flexibility, the relative stabilities of the anti-syn, anti-anti, and syn-syn conformers of o-ClPhBA, m-ClPhBA, and p-ClPhBA are 0.0, 4.66, and 6.76 kcal/mol, respectively, at the B3LYP/6-311++G(d,p) level of theory. For the HF/6-311++G(d,p) level of theory, the relative stabilities are 0.00, 4.54, and 6.11 kcal/mol for o-ClPhBA; 0.00, 3.98, and 1.51 kcal/mol for m-ClPhBA; and 0.00, 4.10, and 1.44 kcal/mol for p-ClPhBA, respectively. Some of the determined stable conformations of these molecules are different in symmetry groups. It was observed that the increase in the symmetry was effective in the of molecular properties, especially for vibrational frequencies. The structural parameter, dipole moments (μ), vibrational frequencies, polarizability (α), hyperpolarizability (β), the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) of the stable conformers were calculated by using Ab initio HF/6-311++G(d,p) and DFT/B3LYP/6-311++G(d,p) level of theory. The assignments of fundamental vibrational modes of the studied molecule were performed based on total energy distribution (TED) analysis.

Controlled Sublimation Rate of Guest Drug from Polymorphic Forms of a Cyclodextrin-Based Polypseudorotaxane Complex and Its Correlation with Molecular Dynamics as Probed by Solid-State NMR

Encapsulation of active pharmaceutical ingredients (APIs) in confined spaces has been extensively explored as it dramatically alters the molecular dynamics and physical properties of the API. Herein, we explored the effect of encapsulation on the molecular dynamics and physical stability of a guest drug, salicylic acid (SA), confined in the intermolecular spaces of γ-cyclodextrin (γ-CD) and poly(ethylene glycol) (PEG)-based polypseudorotaxane (PPRX) structure. The sublimation tendency of SA encapsulated in three polymorphic forms of the γ-CD/PEG-based PPRX complex, monoclinic columnar (MC), hexagonal columnar (HC), and tetragonal columnar (TC), was investigated. The SA sublimation rate was decreased by 3.0-6.6-fold and varied in the order of MC form > HC form > TC form complex. The 13C and 1H magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectra and 13C spin-lattice relaxation time (T1) indicated that the encapsulated SA molecules existed as the monomeric form, and its molecular mobility increased in the order of MC form > HC form > TC form complex. In the complexes, a rapid chemical exchange between two dynamic states of SA (free and bound) was suggested, with varying adsorption/desorption rates accounting for its distinct molecular mobility. This adsorption/desorption process was influenced by proton exchange at the interaction site and interaction strength of SA in the complexes, as evidenced by 1H MAS spectra and temperature dependency of the 13C carbonyl chemical shift. A positive correlation between the molecular mobility of SA and its sublimation rate was established. Moreover, the molecular mobility of γ-CD and PEG in the complexes coincided with that of SA, which can be explained by fast guest-driven dynamics. This is the first report on the stability improvement of an API through complexation in polymorphic supramolecular host structures. The relationship between the molecular dynamics and physical properties of encapsulated API will aid in the rational design of drug delivery systems.

A painless and flexible bi-directional blood glucose-regulating system inspired by an inverter air conditioner

Pursuing painless and flexible blood glucose regulation has been a century-long arduous mission. The current therapeutic systems can only regulate blood glucose unidirectionally (reduce), and the adjustment range is large, which is prone to the risk of hypoglycemia. Herein, inspired by the temperature fluctuation range controlled by the inverter air conditioner, we report a new bi-directional blood glucose-regulating drug delivery system (BDRS) consisting of glucose-loaded pressure-responsive nano-vesicles (Glu@PRNV), insulin-loaded black phosphorus nanosheets (Insulin@BPNs), hydrogel, and a painless blood sugar monitor patch. At first, BDRS could monitor blood glucose in real-time through visible color changes. Afterward, according to different requirements, BDRS could release glucose with the guidance of external pressure, or supplement insulin under near-infrared (NIR) irradiation, through which, the blood glucose level of diabetics could be accurately accommodated within a reasonable fluctuation range, thus minifying the likelihood of sudden hyperglycemia or hypoglycemia. Collectively, the supply-demand balance of blood glucose could be maintained via this real-time bi-directional drug delivery system, thereby improving the quality of life of diabetics. We have also verified the universality of this technique through a similar bi-directional sleep regulation.

Stimuli-responsive Polymeric nanosystems for therapeutic applications

BACKGROUND

Recent past decades have reported emerging of polymeric nanoparticles as a promising technique for controlled and targeted drug delivery. As nanocarriers, they have high drug loading and delivery to the specific site or targeted cells with an advantage of no drug leakage within en route and unloading of a drug in a sustained fashion at the site. These stimuli-responsive systems are functionalized in dendrimers, metallic nanoparticles, polymeric nanoparticles, liposomal nanoparticles, quantum dots.

PURPOSE OF REVIEW

The authors reviewed the potential of smart stimuli-responsive carriers for therapeutic application and their behavior in external or internal stimuli like pH, temperature, redox, light, and magnet. These stimuli-responsive drug delivery systems behave differently in In vitro and In vivo drug release patterns. Stimuli-responsive nanosystems include both hydrophilic and hydrophobic systems. This review highlights the recent development of the physical properties and their application in specific drug delivery.

CONCLUSION

The stimuli (smart, intelligent, programmed) drug delivery systems provide site-specific drug delivery with potential therapy for cancer, neurodegenerative, lifestyle disorders. As development and innovation, the stimuli-responsive based nanocarriers are moving at a fast pace and huge demand for biocompatible and biodegradable responsive polymers for effective and safe delivery.

ANALYSIS OF CARBOHYDRATES AND GLYCOCONJUGATES BY MATRIX-ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY: AN UPDATE FOR 2015-2016

This review is the ninth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2016. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented over 30 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show no sign of deminishing. © 2020 Wiley Periodicals, Inc.

Cell Adhesive Character of Phenylboronic Acid-Modified Insulin and Its Potential as Long-Acting Insulin

Phenylboronic acid (PBA) derivatives have attracted substantial attention owing to their unique character of forming dynamic covalent bonds with polyol compounds. Recent studies have shown interactions between PBA and sugar chains on the cell surface; they have interesting applications for sensors and drug delivery systems. In this study, we prepared phenylboronic acid-modified insulin (PBA-Ins) to evaluate its glucose-lowering activity and cell adhesiveness. In the case of intravenous injection, PBA-Ins showed longer glucose-lowering activity than native insulin. We hypothesized that this prolonged effect was the result of the interaction between the PBA moiety and sugar chains on the cell surface. Red blood cells (RBCs) were used as a cell model, and we confirmed PBA-Ins's affinity for RBCs, which induced RBC agglutination. Interestingly, using an alternative PBA-Ins administration route markedly changed its glucose-lowering activity. Unlike the intravenous injection of PBA-Ins, the subcutaneous injection showed a small effect on glucose level, which indicated that a small amount of PBA-Ins was absorbed into the bloodstream. This suggested the importance of investigating the interaction between the PBA moiety and many types of cells, such as adipocytes, in subcutaneous tissues.

Biomedical nanomotors: efficient glucose-mediated insulin release

We report herein the design of an autonomous glucose-responsive smart nanomachine for insulin (In) delivery based on ultrasound (US)-propelled nanomotors combined with an enzyme-based sensing-effector unit. Gold nanowire (AuNW) motors have been coupled with a mesoporous silica (MS) segment, which was gated with pH-responsive phenylboronic acid (PBA)-glucose oxidase (GOx) supramolecular nanovalves responsible for the insulin release. Glucose-induced protonation of the PBA groups triggers the opening of the pH-driven gate and uncapping of the insulin-loaded nanovalves. The insulin-loaded MS-Au nanomotors displayed an efficient US-driven movement that dramatically accelerates the glucose-triggered insulin release when compared to their static counterparts. Such coupling of the locomotion of nanovehicles with gated insulin-containing nanocontainers and glucose-responsive nanovalves holds great promise for the improved management of diabetes.

Potential Use of Cyclodextrins as Drug Carriers and Active Pharmaceutical Ingredients

Cyclodextrins (CyDs) are extensively used in various fields, and especially have been widely utilized as pharmaceutical excipients and drug carriers in the pharmaceutical field. Owing to the multi-functional and biocompatible characteristics, CyDs can improve the undesirable properties of drug molecules. This review outlines the current application of CyDs in pharmaceutical formulations, focusing on their use as CyD-based drug carriers for several kinds of drugs. Additionally, CyDs have great potential as active pharmaceutical ingredients against various diseases with few side effects.