Search Results (132)

Biogenic silver nanoparticles (AgNPs) were synthesized via a green chemistry strategy using wheat extract and subsequently functionalized with a carboxymethyl chitosan–cinnamaldehyde (CMC=CIN) conjugate through covalent imine bonding. The resulting nanohybrid (AgNP–CMC=CIN) was extensively characterized to confirm successful biofunctionalization: UV–Vis spectroscopy revealed characteristic cinnamaldehyde absorption peaks; ATR-FTIR spectra confirmed polymer–terpene bonding; and TEM analysis evidenced uniform nanoparticle morphology. Dynamic light scattering (DLS) measurements indicated an increase in hydrodynamic size upon coating (from 59.46 ± 12.63 nm to 110.17 ± 4.74 nm), while maintaining low polydispersity (PDI: 0.29 to 0.27) and stable surface charge (zeta potential ~ −30 mV), suggesting colloidal stability and homogeneous polymer encapsulation. Antifungal activity was evaluated against Fusarium oxysporum, Penicillium citrinum, Aspergillus niger, and Aspergillus brasiliensis. The minimum inhibitory concentration (MIC) against F. oxysporum was significantly reduced to 83 μg/mL with AgNP–CMC=CIN, compared to 708 μg/mL for uncoated AgNPs, and was comparable to the reference fungicide tebuconazole (52 μg/mL). Seed priming with AgNP–CMC=CIN led to improved germination (85%) and markedly reduced fungal colonization, while maintaining a favorable phytotoxicity profile. These findings highlight the potential of polysaccharide-terpene-functionalized biogenic AgNPs as a sustainable alternative to conventional fungicides, supporting their application in precision agriculture and integrated crop protection strategies. Full article

Incorporating health-promoting resveratrol into food products is challenging, primarily due to its poor solubility. Covalent conjugation is a promising, low-energy, and environmentally friendly strategy to overcome this limitation. This study compared the effectiveness of free radical grafting and alkaline methods for covalently conjugating whey protein isolate (WPI) with resveratrol. Conjugates were evaluated for molecular weight, structural characteristics, functional properties, and antioxidant activities. Both methods yielded conjugates with enhanced solubility relative to native resveratrol, with fold increases from 7.6 to 21.7 for the free radical grafting and from 8.1 to 23.6 for the alkaline method. Conjugates prepared via free radical grafting exhibited greater increases in molecular weight (10–100 kDa range), higher resveratrol incorporation (up to 17.6%), and superior functional properties compared to the alkaline conjugates (p < 0.05). Specifically, emulsifying activity, foaming capacity, and foaming stability improved by up to 64.7%, 45.8%, and 220.9%, respectively, compared to WPI. The antioxidant activities of the free radical grafting conjugates were 1.3- to 3.6-fold higher than those of alkaline conjugates. These findings highlight free radical grafting of WPI as a promising approach for incorporating resveratrol and improving the functionality of protein-based ingredients in functional food products. Full article

Background/Objectives: The increasing prevalence of multidrug-resistant bacteria presents a major global health challenge, prompting a search for innovative antimicrobial strategies. This study aimed to develop and evaluate a novel nanobiostructure combining alumina nanoparticles (NPs) with the antimicrobial peptide lunatin-1 (Lun-1), forming peptide-functionalized nanofilaments. The main objective was to investigate how the site of peptide functionalization (C-terminal vs. N-terminal) affects membrane interactions and antibacterial activity. Methods: NP–peptide conjugates were synthesized via covalent bonding between lun-1 and alumina NP and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), zeta potential analysis, dynamic light scattering (DLS), Fourier-transform infrared (FTIR), and solid-state ¹³C NMR. Antibacterial activities were assessed against different Gram-positive and Gram-negative strains. Biophysical analyses, including circular dichroism (CD), isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), and solid-state ²H NMR, were employed to evaluate peptide–membrane interactions in the presence of membrane-mimetic vesicles composed of POPC:POPG (3:1) and DMPC:DMPG (3:1). Results: Characterization confirmed the successful formation of NP–peptide nanofilaments. Functionalization at the N-terminal significantly influenced both antibacterial activity and peptide conformation compared to C-terminal attachment. Biophysical data demonstrated stronger membrane interaction and greater membrane disruption when lun-1 was conjugated at the N-terminal. Conclusions: The site of peptide conjugation plays a crucial role in modulating the biological and biophysical properties of NP–lunatin-1 conjugates. C-terminal attachment of lunatin-1 retains both membrane interaction and antibacterial efficacy, making it a promising strategy for the design of peptide-based nanotherapeutics targeting resistant pathogens. Full article

A primary challenge in the further development of anion sensors in real water samples of environmental concern is the need for highly water-soluble compounds that are able to detect low concentrations of analytes. Small-molecule sensors can mitigate solubility constraints and highly aromatic or conjugated systems may provide a new way to recognize target analytes with high sensitivity and/or selectivity. Organic aggregates that have the ability to form large frameworks can exhibit aggregated-induced emissions to detect target analytes, and their coagulation can provide enhanced detection via colorimetric or fluorescent measurements. This review aims to draw attention to the emerging area of small-molecule organic chemosensors that utilize aggregation to detect environmentally detrimental anions in an aqueous solution. A number of mechanisms of interaction for anion recognition are recognized and discussed here, including electrostatic interactions, covalent bond formation, hydrophobic interactions, and even complexation. Full article

This study investigates the pH-responsive dissociation mechanism of carbon dot (CD) conjugated with the anticancer peptide proximicin-A (PROXI) using density functional theory (DFT) simulations. The CD@PROXI system, designed for targeted cancer therapy, releases the drug in acidic environments typical of cancer sites. DFT simulations, with the B3LYP-D3BJ functional and 6-311G (d, p) basis set, optimized the conjugate’s geometry under neutral and acidic conditions. The focus was on the pH-sensitive C=N bond, existing in two protonation states. Key parameters evaluated included the HOMO-LUMO gap, bond length, IR spectroscopy, non-covalent interaction (NCI), electron localization function (ELF), density of states (DOSs), and electrostatic potential (ESP). Under neutral pH, the system showed stability with a HOMO-LUMO gap of 3.22 eV, indicating low reactivity. In acidic pH, this gap decreased to 0.40 eV, suggesting higher reactivity and potential for drug release. IR spectroscopy indicated weakened C=N bonds in acidic conditions, with bond length increasing from 1.288 Å to 1.324 Å. NCI analysis revealed increased van der Waals interactions, supporting bond weakening. ELF analysis showed electron localization at reactive sites, while DOS profiles and ESP maps highlighted distinct electronic states and potential dissociation regions in acidic conditions. These findings confirm the potential of CD@PROXI for targeted cancer therapy, with drug release triggered by the acidic tumor microenvironment. Full article

Doxorubicin (DOX) is one of the most widely used chemotherapy drugs in the treatment of both solid and liquid tumors in patients of all age groups. However, it is likely to produce several side effects that include doxorubicin cardiomyopathy. Nanoparticles (NPs) can offer targeted delivery and release of the drug, potentially increasing treatment efficiency and alleviating side effects. This makes them a viable vector for novel drug delivery systems. Currently, DOX is commonly conjugated to NPs by non-covalent conjugation–physical entrapping of the drug using electrostatic interactions, van der Waals forces, or hydrogen bonding. The reported downside of these methods is that they provide a low drug loading capacity and a higher drug leakage possibility. In comparison to this, the covalent conjugation of DOX via amide (typically formed by coupling carboxyl groups on DOX with amine groups on the nanoparticle or a linker, often facilitated by carbodiimide reagents), hydrazone (which results from the reaction between hydrazines and carbonyl groups, offering pH-sensitive cleavage for controlled release), or disulfide bonds (formed through the oxidation of thiol groups and cleavable by intracellular reducing agents such as glutathione) is more promising as it offers greater bonding strength. This review covers the covalent conjugation of DOX to three different types of NPs—metallic, silica/organosilica, and polymeric—including their corresponding release rates and mechanisms. Full article

The autophagy-related ubiquitin-like conjugation systems, the ATG8 and ATG12 systems, are universally conserved in eukaryotes. However, the covalent bond in the ATG12 system has recently been shown to be evolutionarily lost in Apicomplexa. Here, we show that all genes associated with the ATG12 system are absent in piroplasmida, a lineage within Apicomplexa. Comparative genomics of ATGs further shows that piroplasm ATG3 has lost the region necessary for ATG12 binding. However, our in vitro functional analysis using recombinant proteins demonstrated that ATG3 retained the ability to interact with ATG8 in Babesia bovis, a model species in piroplasmida. These findings provide evidence that the ATG8 system is functional, while the ATG12 system is completely lost in the common ancestor of piroplasmida and highlight the evolutionary flexibility of the ATG12 system in Apicomplexa. Full article

Since its conceptualization, click chemistry in all its variants has proven to be a superior synthesis protocol, compared to conventional methods, for forming new covalent bonds under mild conditions, orthogonally, and with high yields. If a term like reactive resilience could be established, click reactions would be good examples, as they perform better under increasingly challenging conditions. Particularly, highly hindered couplings that perform poorly with conventional chemistry protocols—such as those used to conjugate biomacromolecules (e.g., proteins and aptamers) or multiple drugs onto macromolecular platforms—can be more easily achieved using click chemistry principles, while also promoting high stereoselectivity in the products. In this review, three molecular platforms relevant in the field of nanomedicine are considered: polymers/copolymers, cyclodextrins, and fullerenes, whose functionalization poses a challenge due to steric hindrance, either from the intrinsic bulk behavior (as in polymers) or from the proximity of confined reactive sites, as seen in cyclodextrins and fullerenes. Their functionalization with biologically active groups (drugs or biomolecules), primarily through copper-catalyzed azide–alkyne cycloaddition (CuAAC), strain-promoted azide–alkyne cycloaddition (SPAAC), inverse electron-demand Diels–Alder (IEDDA) and thiol–ene click reactions, has led to the development of increasingly sophisticated systems with enhanced specificity, multifunctionality, bioavailability, delayed clearance, multi-targeting, selective cytotoxicity, and tracking capabilities—all essential in the field of nanomedicine. Full article

Porphyrin’s excellent biocompatibility and modifiability make it a widely studied photoactive material. However, its large π-bond conjugated structure leads to aggregation and precipitation in physiological solutions, limiting the biomedical applications of porphyrin-based photoactive materials. It has been demonstrated through research that fabricating porphyrin molecules into nanoscale covalent organic frameworks (COFs) structures can circumvent issues such as poor dispersibility resulting from hydrophobicity, thereby significantly augmenting the photoactivity of porphyrin materials. Porphyrin-based COF materials can exert combined photodynamic and photothermal effects, circumventing the limitations of photodynamic therapy (PDT) due to hypoxia and issues in photothermal therapy (PTT) from heat shock proteins or the adverse impact of excessive heat on the protein activity of normal tissue. Furthermore, the porous structure of porphyrin COFs facilitates the circulation of oxygen molecules and reactive oxygen species and promotes sufficient contact with the lesion site for therapeutic functions. This review covers recent progress regarding porphyrin-based COFs in treating malignant tumors and venous thrombosis and for antibacterial and anti-inflammatory uses via combined PDT and PTT. By summarizing relevant design strategies, ranging from molecular design to functional application, this review provides a reference basis for the enhanced phototherapy application of porphyrin-based COFs as photoactive materials. This review aims to offer valuable insights for more effective biomedical applications of porphyrin-based COFs through the synthesis of existing experimental data, thereby paving the way for their future preclinical utilization. Full article

The direct discharge of cationic surfactants into environmental matrices has exponentially increased due to their wide application in many products. These compounds and their degraded products disrupt microbial dynamics, hinder plant survival, and affect human health. Therefore, there is an urgent need to develop electroanalytical assessment techniques for their identification, determination, and monitoring. In our study, ZnO-PANI nanocomposites were electrodeposited on a glassy carbon electrode (GCE), followed by the immobilization of laccase enzymes and the electrodeposition of polypyrrole (PPy), to form a biosensor that was used for the detection of CTAB. A UV-Vis analysis showed bands corresponding to the π-π* transition of benzenoid and quinoid rings, π-polaron band transition and n-π*polaronic transitions associated with the extended coil chain conformation of PANI, and the presence and interaction of ZnO with PANI and type 3 copper in the laccase enzymes. The FTIR analysis exhibited peaks corresponding to N-H and C-N stretches and bends for amine, C=C stretches for conjugated alkenes, and a C-H bend for aromatic compounds. A high-resolution scanning electron microscopy (HRSEM) analysis proved that PANI and ZnO-PANI were deposited as fibres with hairy topography resulting from covalent bonding with the laccase enzymes. The modified electrode (PPy-6/GCE) was used as a platform for the detection of CTAB with three linear ranges of 0.5–100 µM, 200–500 µM, and 700–1900 µM. The sensor displayed a high sensitivity of 0.935 μA μM⁻¹ cm⁻², a detection limit of 0.0116 µM, and acceptable recoveries of 95.02% and 87.84% for tap water and wastewater, respectively. Full article

Oligo(phenylene ethynylene)s (OPEs) are π-conjugated systems with promising optical, bioactive, and electrical properties, making them valuable candidates for molecular electronics and biosensors. Controlling the arrangement and orientation of π-conjugated systems is crucial in developing molecular devices. Recently, we developed insulated diarylacetylene dimers using a [c2]daisy chain rotaxane strategy, which brings two cores into close proximity without covalent bonding and shields them with permethylated α-cyclodextrins. Here, we synthesized an insulated OPE dimer using a similar rotaxane strategy to investigate its optical properties. The rotaxane structure and optical properties were evaluated using nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization high-resolution mass spectrometry (ESI-HRMS), and absorption and fluorescence spectroscopy. This study is expected to contribute to the development of optical and electronic materials utilizing OPEs. Full article

The gonadotropin-releasing hormone (GnRH) receptor (GnRH-R) is highly expressed in ovarian cancer cells (OCC), and it is an important molecular target for cancer therapeutics. To develop a new class of drugs targeting OCC, we designed and synthesized Con-3 and Con-7 which are novel high-affinity GnRH-R agonists, covalently coupled through a disulfide bond to the DNA synthesis inhibitor mitoxantrone. We hypothesized that Con-3 and Con-7 binding to the GnRH-R of OCC would expose the conjugated mitoxantrone to the cellular thioredoxin, which reduces the disulfide bond of Con-3 and Con-7. The subsequent release of mitoxantrone leads to its intracellular accumulation, thus exerting its cytotoxic effects. To test this hypothesis, we determined the cytotoxic effects of Con-3 and Con-7 using the SKOV-3 human OCC. Treatment with Con-3 and Con-7, but not with their unconjugated GnRH counterparts, resulted in the accumulation of mitoxantrone within the SKOV-3 cells, increased their apoptosis, and reduced their proliferation, in a dose- and time-dependent manner, with half-maximal inhibitory concentrations of 0.6–0.9 µM. It is concluded that Con-3 and Con-7 act as cytotoxic “prodrugs” in which mitoxantrone is delivered in a GnRH-R-specific manner and constitute a new class of lead compounds for use as anticancer drugs targeting ovarian tumors. Full article

RNA is a promising nucleic acid-based biomolecule for various treatments because of its high efficacy, low toxicity, and the tremendous availability of targeting sequences. Nevertheless, RNA shows instability and has a short half-life in physiological environments such as the bloodstream in the presence of RNAase. Therefore, developing reliable delivery strategies is important for targeting disease sites and maximizing the therapeutic effect of RNA drugs, particularly in the field of immunotherapy. In this mini-review, we highlight two major approaches: (1) delivery vehicles and (2) chemical modifications. Recent advances in delivery vehicles employ nanotechnologies such as lipid-based nanoparticles, viral vectors, and inorganic nanocarriers to precisely target specific cell types to facilitate RNA cellular entry. On the other hand, chemical modification utilizes the alteration of RNA structures via the addition of covalent bonds such as N-acetylgalactosamine or antibodies (antibody–oligonucleotide conjugates) to target specific receptors of cells. The pros and cons of these technologies are enlisted in this review. We aim to review nucleic acid drugs, their delivery systems, targeting strategies, and related chemical modifications. Finally, we express our perspective on the potential combination of RNA-based click chemistry with adoptive cell therapy (e.g., B cells or T cells) to address the issues of short duration and short half-life associated with antibody–oligonucleotide conjugate drugs. Full article

The synthesis and characterization of biocompatible three different maleic anhydride co-polymer conjugated with two different beta-lactam antibiotics at in vitro conditions were conducted. The polymer–drug conjugates were synthesized by coupling β-lactam antibiotics via amide bonds to the copolymer. In this work, six different drug-functionalized maleic anhydride copolymers (DFMACs) were synthesized by the chemical conjugation method. This method is based on the ring-opening reaction of the anhydride ring of the copolymer to form an amide bond linking the drug. The synthesized DFMACs were characterized by ¹H NMR and FTIR/ATR spectroscopies and analyses were carried out by UV/VIS spectroscopy and Zeta-sizer instrument in detail with consecutive antibacterial tests. The existence of a newly formed amide covalent bond between the drug and the copolymer chains was confirmed by ¹H NMR and FTIR/ATR studies. This is the first report on the application of the selected branched biodegradable polymeric matrices for the covalent conjugation of ampicillin and cefalexin. Optimum stability and activity conditions for the synthesized DFMACs were determined. Analyses were conducted under in vitro conditions including varying pH values and simulated body fluids as a function of time to obtain new drug delivery system candidates for the two different antibiotics. Full article

Hydrogen peroxide (H₂O₂) is one of the most environmentally friendly and versatile chemical oxidizing agents, with only O₂ and H₂O as reaction products. It is widely used in environmental protection, industrial production, and medical fields. At present, most of the industrial production of H₂O₂ adopts anthraquinone oxidation, but there are shortcomings such as pollution of the environment and large energy consumption. Covalent organic frameworks (COFs) are a class of porous crystalline materials formed by organic molecular building blocks connected by covalent bonds. The ordered conjugated structure of COFs not only facilitates the absorption of light energy but also promotes the transport of excited-state electrons. Therefore, the photochemical synthesis of H₂O₂ from water and oxygen using photocatalysts based on COFs as a green route has attracted much attention. In this review, we provide an overview of recent studies on COFs as photocatalysts and the different mechanisms involved in the photocatalytic production of hydrogen peroxide. Then, we summarize the various strategies to improve the performance. Finally, we outline the challenges and future directions of COFs in practical applications. This review highlights the potential and application prospects of COFs in the photochemical synthesis of H₂O₂, aiming to provide guidance for the design of COF-based catalysts and the optimization for photocatalytic production of H₂O₂, in order to promote scientific development and application in this field. Full article