Polymer Structure Research Articles

Anthracene-Based Endoperoxides as Self-Sensitized Singlet Oxygen Carriers for Hypoxic-Tumor Photodynamic Therapy.

Singlet oxygen is a crucial reactive oxygen species (ROS) in photodynamic therapy (PDT). However, the hypoxic tumor microenvironment limits the production of cytotoxic singlet oxygen through the light irradiation of PDT photosensitizers (PSs). This restriction poses a major challenge in improving the effectiveness of PDT. To overcome this challenge, researchers have explored the development of singlet oxygen carriers that can capture and release singlet oxygen in physiological conditions. Among these developments, anthracene-based endoperoxides, initially discovered almost 100 years ago, have shown the ability to generate singlet oxygen controllably under thermal or photo stimuli. Recent advancements have led to the development of a new class of self-sensitized anthracene-endoperoxides, with potential applications in enhancing PDT effects for hypoxic tumors. This review discusses the current research progress in utilizing self-sensitized anthracene-endoperoxides as singlet oxygen carriers for improved PDT. It covers anthracene-conjugated small organic molecules, metal-organic complexes, polymeric structures, and other self-sensitized nano-structures. The molecular structural designs, mechanisms, and characteristics of these systems will be discussed. This review aims to provide valuable insights for developing high-performance singlet oxygen carriers for hypoxic-tumor PDT.

Prediction of Delamination Defects in Drilling of Carbon Fiber Reinforced Polymers Using a Regression-Based Approach

Carbon fiber-reinforced polymer (CFRP) structures have been increasingly used in various aerospace sectors due to their outstanding mechanical properties in recent years. However, the poor machinability of CFRP plates, combined with the inhomogeneous behavior of fibers, poses a challenge for manufacturers and researchers to define the critical factors and conditions necessary to ensure the quality of holes in CFRP structures. This study aims to analyze the effect of drilling parameters on CFRP delamination and to predict hole quality using a regression-based approach. The design of the experiment (DOE) was conducted using Taguchi’s L9 3-level orthogonal array. The input drilling variables included the feed rate, spindle speed, and three different drill types. A regression-based model using partial least squares (PLS) was developed to predict delamination defects during the drilling of CFRP plates. The PLS model demonstrated high accuracy in predicting delamination defects, with a Mean Squared Error (MSE) of 0.0045, corresponding to an accuracy of approximately 99.6%, enabling the rapid estimation of delamination. The model’s predictions were closely aligned with the experimental results, although some deviations were observed due to tool inefficiencies, particularly with end mill cutters. These findings offer valuable insights for researchers and practitioners, enhancing the understanding of delamination in CFRPs and identifying areas for further investigation.

Enhancing CO2/N2 and CO2/CH4 Separation Properties of PES/SAPO-34 Membranes Using Choline Chloride-Based Deep Eutectic Solvents as Additives

CO2 separation is an important environmental method mainly used in reducing CO2 emissions to mitigate anthropogenic climate change. The use of mixed-matrix membranes (MMMs) arrives as a possible answer, combining the high selectivity of inorganic membranes with high permeability of organic membranes. However, the combination of these materials is challenging due to their opposing nature, leading to poor interactions between polymeric matrix and inorganic fillers. Many additives have been tested to reduce interfacial voids, some of which showed potential in dealing with compatibility problems, but most of them lack further studies and optimization. Deep eutectic solvents (DESs) have emerged as IL substitutes since they are cheaper and environmentally friendly. Choline chloride-based deep eutectic solvents were studied as additives in polyethersulfone (PES)/SAPO-34 membranes to improve CO2 permeability and CO2/N2 and CO2/CH4 selectivity. SAPO-34 crystals of 150 nm with a high surface area and microporosity were synthesized using dry-gel methodology. The PES/SAPO-34 membranes were optimized following previous work and used in a defined composition, using 5 or 10 w/w% of DES during membrane preparation. All MMMs were characterized by their ideal gas permeability using N2 and CO2 pure gasses. Selected membranes were also tested using CH4 pure gas. The results presented that 5 w/w%, in polymer mass, of ChCl–glycerol presented the best result over the synthesized membranes. An increase of 200% in CO2 permeability maintains the CO2/N2 selectivity for the non-modified PES/SAPO-34 membrane. A CO2/CH4 selectivity of 89.7 was obtained in PES/SAPO-34/ChCl-glycerol membranes containing 5 w/w% of this DES, which is an outstanding ideal separation performance for MMMs when compared to other results in the literature. FTIR analysis reiterates the presence of glycerol in the membranes prepared. Dynamic Mechanical Thermal Analysis (DMTA) shows that the addition of 5 w/w% of DES does not impact the membrane flexibility or polymer structure. However, in concentrations higher than 10 w/w%, the inclusion of DES could lead to high membrane rigidification without impacting the overall thermal resistance. SEM analysis of DES-enhanced membranes presented asymmetric final membranes and reaffirmed the results obtained in DMTA about rigidified structures and lower zeolite–polymer interaction with higher concentrations of DES.

Atmospheric Pressure Photoionization with Halogen Anion Attachment for Mass Spectrometric Analysis of Hydrocarbons and Hydrocarbon-Based Polymers.

Aliphatic hydrocarbons and hydrocarbon-based synthetic polymers are of interest in many fields, but their characterization by mass spectrometric methods is generally limited due to their poor ionizability. Recently, atmospheric pressure photoionization (APPI), combined with halogen anion attachment in negative-ion mode, has drawn attention as a potential method for ionizing various polymers without extensive fragmentation or other unwanted side reactions. In this work, the applicability of halogen anion attachment with APPI was studied using several synthetic polymers, including polyethylene, polypropylene, polyisoprene, and polystyrene, as well as simple n-alkanes of various chain lengths. For hydrocarbon-based polymers, the method produced clear distributions of intact polymer adduct ions when different halogen anions were used. It was found that increasing the halogen anion size decreased ionization efficiency, particularly in the absence of π-bonds in the polymer structure. Testing with simple n-alkanes showed that only molecules containing fifty or more carbon atoms formed detectable halogen adducts, possibly due to the low gas-phase stabilities of the lighter n-alkane adduct ions. In conclusion, halogen anion attachment with negative-ion APPI appears to be a highly promising method for polymer analysis, providing structural data and clean polymer mass spectra with minimal fragmentation, which can be useful for the identification of unknown samples.

Copolymer Randomization by End‐Group Interchain Exchange Reactions

AbstractTheoretical analysis of the kinetic scheme describing formation and randomization of a binary copolymer due to end‐group interchange reactions is presented. Compact analytical expressions are obtained for the transient and equilibrium values of the copolymer degree of blockiness and fractions of active end‐groups of different types. The resulting copolymer is described by the first‐order Markov statistics, which can be rather far from the Bernoullian one. Its structure is determined by the composition of the system and a single combination of the rate constants of four elementary reactions. The kinetics includes fast and slow stages with characteristic time periods independent of and proportional to the average polymerization degree, respectively. During the fast stage, the initial polymers disappear, whereas the copolymer degree of blockiness is still very low. The distribution of units in the copolymer is Markovian, only if the initial polymers possess the most probable molar mass distributions. At the slow stage copolymer randomization gradually progresses, whereas the distribution of end groups may change in the opposite direction compared to the fast stage. The results can be used to analyze the experimental data on the chain structure of condensation, metathesis, and dynamic covalent polymers, where interchange reactions play a significant role.

High‐potential and Stable Bipolar Cathode for Rechargeable Batteries with Fast‐charging and Wide‐temperature Adaptability

Organic carbonyl compounds have been recognized as promising electrodes due to multiple active sites, abundant element resources and flexible structural designability, while their practical applications are still hindered by the easy solubility and low discharge potential. Herein, a novel bipolar polymer composite (TAC) was well‐designed by grafting p‐type triphenylamine units onto n‐type anthraquinone to form an extended π‐conjugated structure and in‐situ growing on carbon nanotubes, which was proved not only with higher discharge potential but also effectively suppress the dissolution issues. Moreover, TAC combined the advantages of different active sites and behaved a dual‐ion storage mechanism. Benefitting from the in‐situ polymerization process, TAC with tube‐type core‐shell structure exhibited enhanced electron transport and improved utilization of active sites, resulting in high capacity (193 mAh g‐1), outstanding rate performance (fast charging within 17 s), long‐term stability (a high capacity retention of 87% after 1000 cycles) and high mass loading (10 mg cm‐2). Additionally, TAC can well adapt to the temperature change, outputting a capacity of 72 mAh g‐1 at ‐60 °C and 165 mAh g‐1 at 80 °C. Such versatile polymer structure inspires the design of high performance organic materials for rechargeable batteries to satisfy high stability and wide temperature operations.

High-potential and Stable Bipolar Cathode for Rechargeable Batteries with Fast-charging and Wide-temperature Adaptability.

Organic carbonyl compounds have been recognized as promising electrodes due to multiple active sites, abundant element resources and flexible structural designability, while their practical applications are still hindered by the easy solubility and low discharge potential. Herein, a novel bipolar polymer composite (TAC) was well-designed by grafting p-type triphenylamine units onto n-type anthraquinone to form an extended π-conjugated structure and in-situ growing on carbon nanotubes, which was proved not only with higher discharge potential but also effectively suppress the dissolution issues. Moreover, TAC combined the advantages of different active sites and behaved a dual-ion storage mechanism. Benefitting from the in-situ polymerization process, TAC with tube-type core-shell structure exhibited enhanced electron transport and improved utilization of active sites, resulting in high capacity (193 mAh g-1), outstanding rate performance (fast charging within 17 s), long-term stability (a high capacity retention of 87% after 1000 cycles) and high mass loading (10 mg cm-2). Additionally, TAC can well adapt to the temperature change, outputting a capacity of 72 mAh g-1 at -60 °C and165 mAh g-1 at 80 °C. Such versatile polymer structure inspires the design of high performance organic materials for rechargeable batteries to satisfy high stability and wide temperature operations.

Synthesis of basic amino acid-grafted lignin for use as a high-performance pigment dispersant

Lignin is a promising dispersant due to its hyperbranched polymer structure, low cost, renewability and abundant availability. However, its use is limited by its broad molecular weight distribution, inhomogeneity, and low content of hydrophilic functional groups. In this work, lignin was functionalized with alkaline amino acids (EHL-AA) to enhance water solubility and molecular weight uniformity. The results showed that EHL-AA significantly improved the dispersion of pigment Red 57:1 (P.R.57:1) in aqueous solutions, reducing the required dosage by 50 % compared to commercial small-molecule dispersants. Additionally, histidine modified lignin (EHL-His) exhibited superior stability for P.R.57:1 compared to commercial lignosulfonate (REAX 85A). Molecular dynamics simulations further revealed that showed that EHL-His had the highest electrostatic potential difference and the largest absolute value of negative ESP. The adsorption of EHL-His onto the P.R.57:1 surface followed the pseudo-second-order kinetic model and the Langmuir model, with EHL-His showing a higher Langmuir constant (b) than REAX 85A, indicating the strongest interaction with the pigment. In summary, this work advances pigment dispersion technology and promotes the high-value utilization of lignin.

New Insights in the Nanomechanical Study of Carbon-Containing Nanocomposite Materials Based on High-Density Polyethylene

The investigation of new composite materials possessing low weight but not at the expense of their mechanical performance is of great interest in terms of reducing energy consumption in many industrial applications. This study is focused on the nanomechanical characterization of high-density polyethylene (HDPE)-based composite specimens modified with equal loadings of graphene nanoplatelets (GNPs) and/or multiwall carbon nanotubes (MWCNTs). Quasi-static nanoindentation analysis revealed the impact of the carbon nanofillers on the receiving of nanocomposites with higher nanohardness and reduced modulus of elasticity, reaching values of 0.146 GPa and 3.57 GPa, respectively. The role of the indentation size effect in elastic polymer matrix was assessed by applying three distinct peak forces. Nanoscratch experiments depicted the tribological behavior of the composite samples and inferred the influence of the carbon nanofillers on the values of the coefficient of friction (COF). It seems that the incorporation of 4 wt% GNPs in the polymer structure improves the scratch resistance of the material, resulting in a higher value of the exerted lateral force and therefore leading to the detection of a higher coefficient of friction at scratch of 0.401. A considerable pile-up response of the scratched polymer specimens was observed by means of in-situ SPM imaging of the tested surface sample area. The sway of the carbon nanoparticles on the composite pile-up behavior and the effect of the pile-up on the measured friction coefficients have been explored.

Assessment of the degree of ripeness of oriental persimmon fruits (Diospyros kaki L.) by tensor stress

The object of the study is persimmon fruits, which occupy an important place among subtropical crops and have a wide development prospect. Since these fruits are difficult to process, they are mainly used fresh. The usefulness of these fruits is associated with their chemical composition. This composition includes biologically active substances, microelements, various mono- and polysaccharides, saturated and unsaturated fatty acids, etc. The complexity of the technological processing of persimmon fruits is associated with its astringent taste, which is determined by the amount of polyphenolic compounds. In general, the strength of raw materials is manifested not only in the degree of ripeness, but also in its technological processing processes, which are the object of the study. From this point of view, the hardness of persimmon fruits acts as a subject of study. Data on the property of fruits and vegetables associated with the stress-hard state is a solution to the problems that arise when expanding the range of finished products. For example, it has been established that at the stage of commercial ripeness, the hardness of persimmon fruits is no more than 12.3 kg/cm2. And this indicator changes downwards over time, i.e. to 1.5÷2.0 kg/cm2. Consequently, the possibility of using fruits for the production of various food products is expanding. The study of raw materials according to the laws of solid state physics is explained by its polymer structure. Therefore, the ripening of raw materials depends on the monomerization of this structure. In such decomposition, a condition is created for the combination of various mono-substances, for example, in persimmon fruits, monophenols combine with monosaccharides, which results in a decrease or disappearance of the tart taste of the raw material. Therefore, determining the degree of raw material ripeness by changes in stress will allow to predict its destruction in advance.

Good adsorption performance for both cationic and anionic dyes by a novel crosslinked tetrafluoroterephthalonitrile-tannic acid-chitosan polymer synthesized via one-pot reaction

In this work, tetrafluorophenonitrile was utilized to crosslink tannic acid and chitosan together to form a new crosslinked polymer (CSTTA), and then the Fe3O4 nanoparticles were prepared and immortalized on the CSTTA at the same time to obtain the Fe3O4/CSTTA composite. The structures of CSTTA polymer and Fe3O4/CSTTA composite were characterized by SEM, FTIR, TGA, 13CNMR, XPS, WAXD, N2 adsorption-desorption isotherm, VSM, and zeta potential measurement. The CSTTA could simultaneously adsorb the cationic methylene blue (MB) and anionic orange G (OG), and its adsorption behaviors for MB and OG conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, which were spontaneous according to thermodynamic calculation. The CSTTA possessed not only high adsorption capacities for both MB and OG up to 1092.69 mg/g and 519.89 mg/g at 303 K under the optimal pH conditions of pH=10 and pH=1, respectively, but also the good reused ability. In addition, the Fe3O4/CSTTA composite could also absorb both MB and OG with good magnetically recollected ability to avoid secondary pollution.

Tearing properties, crystallization behavior, microstructure, and morphology of LLDPE with different short branched chain distributions

Abstract The length and distribution of comonomers with short-chain branching (SCB) have a significant influence on the crystallization behavior and crystal structure of polymers, as well as the mechanical properties of the material. This study investigates the crystallization behavior and properties of linear low-density polyethylene (LLDPE) samples with similar density, molecular weight, and branching degree but varying SCB distributions. The results show that LLDPE with butene as the comonomer has a stronger ability to suppress crystallization compared to LLDPE with hexene as the comonomer due to its more uniform SCB distribution. Additionally, among LLDPEs with comonomers of octene, hexene, and butene, the LLDPE with the most uniform SCB distribution exhibits the weakest crystallization ability. Small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) results indicate that LLDPE with more uniform distribution of SCB has smaller long-period and more regular lamellar structure. Therefore, LLDPE with more uniform SCB distribution exhibits weaker inhibition ability towards crystallization, leading to less agglomerated phases and weaker phase separation, resulting in higher tear strength.

Evolution from micropinned to polymeric alloy structure of XLPE‐PS: Improving electrical properties and mechanism

AbstractThis research investigates the transition from a micropinned to a polymeric alloy structure in crosslinked‐polyethylene‐polystyrene (XLPE‐PS). Incorporating 2 wt% 10 μm PS particles into low‐density polyethylene (LDPE) and crosslinking with 2 wt% dicumyl peroxide (DCP) forms XLPE‐PS structures. The polymeric alloy structure, formed at 220°C extrusion, contrasts with the micropinned formed at 150°C. Morphological, thermo‐structural, chemical, and crystal properties are examined to understand their impact on electrical properties and charge transport mechanisms. Results indicate that the polymeric alloy effectively resolves void/crack issues, whereas the micropinned exhibits phase separation. Both structures exhibit a benzene‐crosslinked network, and variations in these structures lead to significant changes in thermo‐structural, chemical, and crystalline properties. The polymeric alloy XLPE‐PS shifts the polyethylene (PE) hkl crystal planes, confirming phase shift and optimal alloying. The structural alterations reveal deeper traps and higher densities in the polymeric alloy XLPE‐PS, leading to significantly improved electrical properties, including reduced DC conductivity by up to 1.3 and 0.7 decades at 30 and 90°C, and increased DC breakdown strength by up to 40.34% and 16.17% at 30 and 90°C, respectively, compared with micropinned XLPE‐PS. This research offers insights into stable high‐voltage insulation development.

Efficient Polymeric Nanoparticle Gene Delivery Enabled Via Tri- and Tetrafunctional Branching.

Poly(β-amino ester) (PBAE) nanoparticles (NPs) show great promise for nonviral gene delivery. Recent studies suggest branched PBAEs (BPBAEs) offer advantages over linear counterparts, but the effect of polymer structure has not been well investigated across many chemical constituents. Here, a library of BPBAEs was synthesized with tri- and tetrafunctional branching. These polymers self-assemble with DNA to form highly cationic, monodisperse NPs with notably small size (∼50 nm). Optimal transfection occurred with polymer structures that featured moderate PBAE branching, enabling complete DNA encapsulation, rapid NP uptake, and robust expression at low DNA doses and polymer amounts. Optimized NPs enabled efficient DNA delivery to diverse cell types in vitro while maintaining high cellular viability, demonstrating significant improvements over a well-performing linear PBAE counterpart. BPBAEs also facilitated efficient mRNA and siRNA delivery, highlighting the versatility of these structures and demonstrating the broad utility of BPBAE NPs as vectors for nucleic acid delivery.

Advanced functional polymer materials for biomedical applications

AbstractPolymer structures are essential in biomedical applications due to their biocompatibility, biodegradability, and ability to form intricate structures on micro‐ to nanometer scales. This review, emphasizing electrospinning and phase inversion techniques, examines the fabrication strategies and chemical design of polymer structures for biomedical use. Electrospinning, particularly needleless electrospinning, produces nanofibres with high porosity and flexibility and is widely applied in tissue engineering and drug delivery. Phase inversion, including thermal, nonsolvent‐, vapor‐ and evaporation‐induced phase separation, allows precise control over polymer properties but faces challenges in terms of cooling rates and solvent characteristics. Chemical design through doping, functionalization, cross‐linking and copolymerization enhances the biocompatibility, biodegradability and mechanical properties of polymers, facilitating advanced applications in drug delivery, tissue scaffolding and biosensors. Advanced functional polymers are revolutionizing biomedical fields, offering innovative solutions for therapeutic medicine delivery, disease detection, diagnostics, and regenerative medicine. Despite remarkable progress, challenges, such as scalability, cost‐effectiveness, and environmental impact, persist. This review underscores the transformative potential of advanced polymer materials in medical treatments and advocates for continuous research and interdisciplinary collaboration to overcome existing challenges and fully exploit the capabilities of these materials in improving patient care and medical outcomes. Future perspectives highlight enhancing precision control mechanisms, integrating phase inversion with other techniques and developing large‐scale production methods to advance the field further.

Practical guidelines and challenges in the isolation and characterization of microplastics/microfibers by Raman microscopy

We address some challenges usually encountered in the analysis of microplastics (MPs) and microfibers (MFs) using Raman microscopy. Those issues are examined considering that the researchers that carry out the collection and analysis of MP contamination may not have necessarily specialized expertise in Raman microscopy or polymer chemistry. Topics such as effective particle isolation or the use of adequate substrates are approached on the base of the impact they have on the spectroscopic characterization. Issues as the control of background signal, the influence of sample digestion, and the presence of internal interferences such as pigments, dyes, and fillers, are discussed. Spectral features of the polymer families found as MP/MF contaminants are presented based upon polymer structure, properties, and applications. The use of open-source libraries to complement chemical identification is also discussed. Overall, this work aims to enhance the practice and understanding of Raman microscopy for researchers engaged in characterizing MP/MF contaminants.

Heat diffusion coefficient study of polymers based on interpretable machine learning

Abstract. Polymers hold significant application value across various fields of modern society, with different application scenarios requiring specific thermal diffusivity coefficients. Finding polymer materials with targeted thermal diffusivities is crucial. However, due to the vast variety and complex structures of polymers, constructing a unified structured dataset for machine learning modeling is challenging. Although machine learning has shown great potential in materials science, it has rarely been applied to predict the heat diffusion coefficient of polymers. This paper constructs a dataset for predicting the thermal diffusion coefficient of polymers using a publicly available dataset by transforming the SMILES code of polymers into eight features with practical physical and chemical meanings. Using the Random Forest algorithm, training with 400 of these data and randomly selecting 200 of them for cross-validation, the accuracy of the test set reached 0.9. Additionally, through interpretability analysis, we found that the molecular weight of the polymer monomers, the TPSA (the polar surface area of the molecule), and the NRB (the number of rotatable bonds) are the main features affecting the polymer thermal diffusion coefficient. An increase in the TPSA and the NRB positively contributes to the thermal diffusivity, while an increase in molecular weight negatively contributes. Our study provides a new method for the prediction of polymer thermal diffusivity and creates a new paradigm for the study of polymer thermal diffusivity, promoting further development in this field.

Adjustment of Mechanical Properties of 3D Printed Continuous Carbon Fiber-Reinforced Thermoset Composites by Print Parameter Adjustments

Reinforcing thermoset polymers with continuous carbon fiber (CF) tow has emerged as a promising avenue to overcome the thermal and mechanical performance limitations of 3D printed polymeric structures for load-bearing applications. Unlike traditional methods, manufacturing continuous fiber-reinforced composites by 3D printing has the unique capability of locally varying the mechanical properties of the composites. In this study, continuous CF thermoset composite specimens were printed with varying line spacing, resin flow rate, and nozzle sizes. The resin flow rates for different line spacings and nozzle sizes were optimized by topographic analysis. Printed composite mechanical properties were evaluated, and their trends were correlated with the trend of print parameter changes. Results showed that tensile strength and modulus could be altered and improved by ~50% by adjusting the printing process parameters. Higher composite strength and modulus were obtained by shortening the line spacing and nozzle diameter.

Effect of Solvents on the Performance and Structure of Polymethylacrylimide Aerogels.

Solvent effects play a critical role in solution polymerization, especially in free radical polymerization, where they influence both monomer-solvent interactions and the resulting polymer structure. In this study, polymethacrylimide (PMI) aerogels were synthesized via freeze-drying using dimethylformamide (DMF), dimethylacetamide (DMAc), and dimethyl sulfoxide (DMSO) as solvents. The effects of monomer reactivity ratios, monomer distribution, and solvent-monomer interactions on the shrinkage, bulk density, pore size, and compressive properties of the aerogels were investigated. Results demonstrated that solvent choice significantly impacted the polymerization process, leading to variations in the structure and properties of the final aerogels. Notably, aerogels synthesized in DMSO, the most polar solvent, exhibited the lowest shrinkage (33.98%), highest density (0.1582 g·cm-3), and highest compressive stress (1695.48 kPa at 70% strain). These findings underscore the importance of solvent selection in controlling the microstructure and enhancing the mechanical performance of PMI aerogels.

Theoretical and Experimental Analyses of the Interfacial Mechanism of Dendrimer-Doxorubicin Complexes Formation.

The work presents correlations between the physicochemical properties of the carrier and the active substance and optimization of the conditions for creating an active system based on PAMAM dendrimers and doxorubicin. The study monitored the influence of the ionized form of the doxorubicin molecule on the efficiency of complex formation. The deprotonated form of doxorubicin occurs under basic conditions in the pH range of 9.0-10.0. In the presence of doxorubicin, changes in the zeta potential of the complex concerning the initial system are observed. These changes result from electrostatic interactions between the drug molecules and external functional groups. Based on changes in the absorbance intensity of UV-vis spectra, the binding of the drug in the polymer structure is observed depending on the pH of the environment and the molar ratio. Optimal conditions for forming complexes occur under alkaline conditions. UV-vis, Fourier transform infrared spectroscopy, and circular dichroism spectroscopy confirmed the stability of the formed dendrimer-DOX complex. Molecular dynamics simulations were conducted to gain a deeper insight into the molecular mechanism of DOX adsorption on and within the G4.0 PAMAM dendrimers. It was observed that the protonation state of both the dendrimer and DOX significantly influences the adsorption stability. The system exhibited high stability at high pH values (∼9-10), with DOX molecules strongly adsorbed on the dendrimer surface and partially within its bulk. However, under lower pH conditions, a reduction in adsorption strength was observed, leading to the detachment of DOX clusters from the dendrimer structure.