Currently there is no successful platform technology for the sustained release of protein drugs. It seems inevitable to specifically develop new materials for such purpose, and hence the understanding of protein-material interactions is highly desirable. In this study, we synthesized cholesterol-grafted polyglutamate (PGA--Chol) as a hydrophobically-modified polypeptide, and thoroughly characterized its interaction with a model protein (human serum albumin) in the aqueous solution by using circular dichroism, fluorescence methods, and light scattering. With the protein concentration fixed at 5 μmol/L, adding PGA--Chol polymers into the solution resulted in continuous blue shift of the protein fluorescence (from 339 to 332 nm), until the polymer molar concentration reached the same value as the protein. In contrast, the un-modified polyglutamate polymers apparently neither affected the protein microenvironment nor formed aggregates. Based on the experimental data, we proposed a physical picture for such protein-polymer systems, where the polymer first bind with the protein in a 1:1 molar ratio a fraction of their hydrophobic pendant cholesterol resides along the polymer chain. In this protein/polymer complex, there are excess unbound cholesterol residues. As the polymer concentration increases, the polymers form multi-polymer aggregates around 200 nm in diameter the same hydrophobic cholesterol residues. The protein/polymer complex also participate in the aggregation their excess cholesterol residues, and consequently the proteins are encapsulated into the nanoparticles. The encapsulation was also found to increase the thermal stability of the model protein.

ObjectiveTo analyse the current implementation status of Chinese herbal medicine （CHM） placebo and systematically evaluate the placebo effect in randomised controlled trials （RCTs） of traditional Chinese medicine （TCM） for the treatment of functional dyspepsia （FD）. MethodsA combination of medical subject terms and free words was used to search six databases， including PubMed， EMBASE， Cochrane Library， Web of Science， China National Knowledge Infrastructure， and Wanfang， for RCTs with CHM placebo group for FD published from January 31st， 1994 to September 30th， 2023. The dosage forms， composition， and methodological quality were collected and evaluated. The quality of the included articles was evaluated by Cochrane risk of bias assessment tool， and meta-analysis was performed on the CHM placebo response rate of patients with FD， and subgroup analysis and meta-regression was performed according to diagnostic criteria， efficacy criteria， duration of treatment， type of placebo， whether it contained active ingredient， and whether it evaluated placebo effects. ResultsA total of 34 publications were included involving 5046 participants， of which 2221 FD patients received CHM placebo treatment. Granules were the predominant placebo preparation， accounting for 71% （24/34）； 32.35% （11/34） of the studies added real CHM to the placebo， and only 12 （35%） of the studies described appearance， odour， and taste. The placebo response rate in FD patients in the placebo group was 41% （95% CI： 0.35 to 0.47； P＜0.01， I² = 87%）； there was significant difference between groups with different diagnostic criteria and different treatment durations （P＜0.05 or P＜0.01）， but there was no significant difference between the different efficacy evaluation criteria， the different placebo preparation， the presence of a low-dose active ingredient， and the presence or absence of placebo assessment （P＞0.05）. ConclusionThere was a significant CHM placebo effect in patients with FD， with granules as the main preparation of placebop. Different diagnostic criteria and different treatment times may affect the response rate of patients， and the addition of low-dose real medicine to the CHM placebos has not been seen to have an effect on the response rate. Clinical investigators have not paid enough attention to placebos， and there is a lack of uniform standards and norms for the preparation and evaluation of CHM placebos.