Exploring spectroscopic insights into molecular recognition of potential anti-Alzheimer's drugs within the hydrophobic pockets of β-cycloamylose

Cationic cycloamylose based nucleic acid nanocarriers

Nucleic acid delivery by viral and non-viral methods has been a cornerstone for the contemporary gene therapy aimed at correcting the defective genes, replacing of the missing genes, or downregulating the expression of anomalous genes is highly desirable for the management of various diseases. Ostensibly, it becomes paramount for the delivery vectors to intersect the biological barriers for accessing their destined site within the cellular environment. However, the lipophilic nature of biological membranes and their potential to limit the entry of large sized, charged, hydrophilic molecules thus presenting a sizeable challenge for the cellular integration of negatively charged nucleic acids. Furthermore, the susceptibility of nucleic acids towards the degrading enzymes (nucleases) in the lysosomes present in cytoplasm is another matter of concern for their cellular and nuclear delivery. Hence, there is a pressing need for the identification and development of cationic delivery systems which encapsulate the cargo nucleic acids where the charge facilitates their cellular entry by evading the membrane barriers, and the encapsulation shields them from the enzymatic attack in cytoplasm. Cycloamylose bearing a closed loop conformation presents a robust candidature in this regard owing to its remarkable encapsulating tendency towards nucleic acids including siRNA, CpG DNA, and siRNA. The presence of numerous hydroxyl groups on the cycloamylose periphery provides sites for its chemical modification for the introduction of cationic groups, including spermine, (3-Chloro-2 hydroxypropyl) trimethylammonium chloride (Q188), and diethyl aminoethane (DEAE). The resulting cationic cycloamylose possesses a remarkable transfection efficiency and provides stability to cargo oligonucleotides against endonucleases, in addition to modulating the undesirable side effects such as unwanted immune stimulation. Cycloamylose is known to interact with the cell membranes where they release certain membrane components such as phospholipids and cholesterol thereby resulting in membrane destabilization and permeabilization. Furthermore, cycloamylose derivatives also serve as formulation excipients for improving the efficiency of other gene delivery systems. This review delves into the various vector and non-vector-based gene delivery systems, their advantages, and limitations, eventually leading to the identification of cycloamylose as an ideal candidate for nucleic acid delivery. The synthesis of cationic cycloamylose is briefly discussed in each section followed by its application for specific delivery/transfection of a particular nucleic acid.

Prominent Perspective on Existing Biological Hallmarks of Alzheimer's Disease

Biomarkers are the most significant diagnosis tools tending towards unique approaches and solutions for the prevention and cure of Alzheimer's Disease (AD). The current report provides a clear perception of the concept of various biomarkers and their prominent features through analysis to provide a possible solution for the inhibition of events in AD. Scientists around the world truly believe that crucial hallmarks can serve as critical tools in the early diagnosis, cure, and prevention, as well as the future of medicine. The awareness and understanding of such biomarkers would provide solutions to the puzzled mechanism of this neuronal disorder. Some of the argued biomarkers in the present article are still in an experimental phase as they need to undergo specific clinical trials before they can be considered for treatment.

Selective detection of tartaric acid using amino acid interlinked silver nanoparticles as a colorimetric probe

A variety of biomolecules with different functional groups play critical roles in almost all the processes occurring in living cells. Interaction of metallic nanoparticles (NPs) with various biomolecules generates a layer of molecules on their surface, and this biomolecular rich layer formed on the NP surface is described as a "biomolecular corona". The physicochemical properties of the NPs, including size, adsorption affinity, and charge on the particles' surfaces are the major factors influencing the characteristics of this corona. The formation of various biomolecular corona has been studied well, whereas the amino acid corona is relatively new by exploring their stability. In the present study, a novel formation of an amino acid corona with a fundamental interaction mechanism for a selective detection procedure using a colorimetric platform has been proposed. Herein, amino acid-coated silver NPs (AgNPs) have been used as a template with spectroscopic (steady state UV-Vis, FTIR) and imaging (HR-TEM, DLS) techniques. Our findings demonstrated that among different amino acid coronas, glutathione (GSH) stabilized AgNPs show a rapid reaction with tartaric acid. The extent and thermodynamics of the formed complex between the GSH/AgNPs and tartaric acid have also been studied and this suggested that the complex formed is spontaneous and energy releasing in nature.

Spectroscopic detection of Hg2+ in water samples using fluorescent carbon quantum dots as sensing probe

Mercury (Hg2+) is remarked as toxic and hazardous element to global environment. Here, carbon quantum dots (CQDs) were synthesized by simple microwave assisted technique for Hg2+ detection in water samples via. fluorescence quenching and FT-IR spectroscopic approach. The morphology and chemical structure of synthesized CQDs was investigated by TEM, FT-IR, 13C-NMR, fluorescence and UV-vis spectroscopic technique. The resultant CQDs bears spherical morphology with an average size of 2–4 nm. The binding parameters, as Stern-Volmer quenching constant (Ksv) and binding constant for CQDs-Hg system was investigated by fluorescence method, whereas UV-vis techniques was employed for determination of thermodynamic parameters, as Gibb’s free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) at three different temperature (295, 298 and 305 K). Moreover, selectivity assay for Hg2+ detection has been studied in presence of other metal ions by FT-IR as well as fluorescence spectroscopy. Analytical assay was also successfully applied for Hg2+ in spiked water samples collected from different areas of Chhattisgarh, with 98–99 recovery %. The detection of Hg2+ has been demonstrated in the range of 0 to 5.0μM with 3.25 nM detection limit. The present method is found to be simple, highly sensitive and selective for sensing of Hg2+ in aquatic environmental samples using CQDs as sensing probe.

Colorimetric determination of L-cysteine in milk samples with surface functionalized silver nanoparticles

A simple, selective and sensitive method is proposed for determination of cysteine (Cys) in milk samples using ionic liquid functionalized silver nanoparticles (ILs-AgNPs) as a colorimetric probe. ILs-AgNPs was synthesized by simple reduction method using silver nitrate as a precursor and sodium borohydride as a reducing agent and functionalized with ILs to prevent particles from self-aggregation. The sensing mechanism has been dependent on the color change of ILs-AgNPs and red shift of absorption band from 395 nm to 560 nm in the visible region, which is found proportional to the concentration of target analyte in sample. ILs-AgNPs was characterized in absence and presence of Cys by UV-vis, Fourier transform-infrared (FTIR) spectroscopy, transmission electron microscope (TEM) and dynamic light scattering (DLS). The linear range was acquired in the range of 0-100 ng mL^-1, with correlation coefficient (R²) of 0.996 and limit of detection (LOD) of 4.0 nM. The binding mechanism and interactions between Cys and ILs-AgNPs was confirmed by calculating the binding constant and thermodynamic parameters such as enthalpy (∆H), entropy (∆S) and Gibb's free energy (∆G). The use of ILs-AgNPs exhibited high colorimetric selectivity for Cys in milk samples in presence of other amino acids. This proposed strategy possessed the advantages of simplicity and selectivity, hence is applied for analysis of Cys in milk samples.

Multi-spectroscopic monitoring of molecular interactions between an amino acid-functionalized ionic liquid and potential anti-Alzheimer's drugs

Inhibiting the formation of amyloid fibrils is a crucial step in the prevention of the human neurological disorder, Alzheimer's disease (AD). Ionic liquid (IL) mediated interactions are an expedient approach that exhibits inhibition effects on amyloid fibrils. In view of the beneficial role of ILs, in this work we have explored complexation of anti-Alzheimer's drugs (i.e., tacrine and PC-37) and an amino acid-functionalized IL [AIL (4-PyC8)]. Maintaining standard physiological conditions, the binding mechanism, thermo-dynamical properties and binding parameters were studied by employing UV-vis, fluorescence, FTIR, ¹H NMR, COSY and NOESY spectroscopy. The present investigation uncovers the fact that the interaction of anti-Alzheimer's drugs with 4-PyC8 is mediated through H-bonding and van der Waals forces. The Benesi–Hildebrand relation was used to evaluate the binding affinity and PC-37 showed the highest binding when complexed with 4-PyC8. FTIR spectra showed absorption bands at 3527.98 cm⁻¹ and 3527.09 cm⁻¹ for the PC-37 + 4-PyC8 system which is quite promising compared to tacrine. ¹H-NMR experiments recorded deshielding for tacrine at relatively higher concentrations than PC-37. COSY investigations suggest that anti-Alzheimer's drugs after complexation with 4-PyC8 show a 1 : 1 ratio. The cross-peaks of the NOESY spectra involve correlations between anti-Alzheimer's drugs and AIL protons, indicating complexation between them. The observed results indicate that these complexes are expected to have a possible therapeutic role in reducing/inhibiting amyloid fibrils when incorporated into drug formulations.

Ionic liquids mediated interactions are an expedient approach that exhibit inhibition effect on amyloid fibrils which is beneficial for the treatment of Alzheimer's disease.

Multi-spectroscopic monitoring of molecular interactions between an amino acid-functionalized ionic liquid and potential anti-Alzheimer's drugs

Ionic liquids mediated interactions are an expedient approach that exhibit inhibition effect on amyloid fibrils which is beneficial for the treatment of Alzheimer's disease.