Estimation of pore sizes in nanoporous materials by argon capillary condensation: the scaling approach

This work is aimed to develop a model for predicting pore sizes in nanoporous materials using argon as a test fluid over a wide range of temperatures. The model is based on the universal form of the Kelvin equation and accounts for the difference in vapor pressure between the center of the condensation meniscus and in bulk. For the first time, a scaling model was applied to build a two-parameter model for pore size prediction using argon capillary condensation data. A multiparametric approximation was created for convenient direct pore size calculation. The findings of this study have important implications for the design and optimization of mesoporous materials for various applications, including gas storage, catalysis, and separation. The developed model provides a more accurate and reliable method for characterizing nanoporous materials, enabling better prediction of pore sizes at different temperatures

Biodegradable Micellar HPMA-Based Polymer–Drug Conjugates with Betulinic Acid for Passive Tumor Targeting

Here, we present the synthesis, physicochemical, and preliminary biological characterization of micellar polymer-betulinic acid (BA) conjugates based on <i>N</i>-(2-hydroxypropyl)­methacrylamide (HPMA) copolymer carriers, enabling the controlled release of cytotoxic BA derivatives in solid tumors or tumor cells. Various HPMA copolymer conjugates differing in the structure of the spacer between the drug and the carrier were synthesized, all designed for pH-triggered drug release in tumor tissue or tumor cells. The high molecular weight of the micellar conjugates should improve the uptake of the drug in solid tumors due to the Enhanced permeability and retention (EPR) effect. Nevertheless, only the conjugate containing BA with methylated carboxyl groups enabled pH-dependent controlled release in vitro. Moreover, drug release led to the disassembly of the micellar structure, which facilitated elimination of the water-soluble HPMA copolymer carrier from the body by renal filtration. The methylated BA derivative and its polymer conjugate exhibited high cytostatic activity against DLD-1, HT-29, and HeLa carcinoma cell lines and enhanced tumor accumulation in HT-29 xenograft in mice