[Research Status of Nanomaterial Medical Device and Discussion on Biological Evaluation].

In recent years, China has made great progress in basic nanomedicine, nanotoxicology and nanobiology research. Nanotechnology has been continuously applied in biomaterial and medical device, more and more medical devices applying nanomaterials are developed and manufactured. In order to gain more comprehension and accurate understanding of the research and industrial development in nanobiomaterial medical devices, this study reviewed the common nanomaterial in medical devices and the regulatory situation of nanomaterial medical devices at home and abroad, and discussed the current challenges in biological evaluation of nanomaterial medical devices, with a view to providing ideas for the safety evaluation and research of related products.

Mechanism of remodeling and local effects in vivo of a new injectable cosmetic filler.

By studying the local effects of a new type of injectable cosmetic filler implanted into the animal to explore the mechanism of remodeling and cosmetic effect of this kind of product. Take 12 rabbits and select 4 implantation points on both sides of the spine, respectively, and implant the test sample (PLLA) and negative control sample (HDPE) into the subcutaneous tissues on both sides. In the same way, take another 12 rabbits and implant the marketing control sample (cross-linked sodium hyaluronate) and negative control sample (HDPE) into the subcutaneous tissues on both sides. The animals were executed at 1 week, 4 weeks, 13 weeks and 52 weeks respectively, and Hematoxylin-Eosin staining, Masson trichrome staining and immunofluorescence staining were performed to characterize the local effects in vivo and the expression of type I collagen (Col. I), type III collagen (Col.III) and matrix metalloproteinase 9 (MMP-9). Good histocompatibility of the test sample and the marketing control sample were found. The foreign body reaction of marketing control sample was more intense than that of the test sample after 13 weeks. The foreign body reaction of testing sample was more intense after 52 weeks, while that of the marketing control sample was more stable. With the process of tissue repair, the collagen fibers of test samples and marketing control samples gradually increased after implantation. Type I collagen was mainly found inside the fiber capsule, while type III collagen was mainly found outside. The positive expression of matrix metalloproteinase 9 gradually increased, the positive expression of test samples increased significantly after 52 weeks, while that of marketing control samples did not change significantly. Good histocompatibility of PLLA filler is found. Matrix metalloproteinase 9 participates in foreign body reaction and collagen formation, which can reflect the process of tissue remodeling.

Hemocompatibility assay of a micro-catheter using hydrophilic coating biomaterials.

For medical devices directly or indirectly contacted with blood, hemocompatibility assay is of great importance during the biological evaluation. In ISO 10993-4:2017 - Biological evaluation of medical devices part 4, a selection of tests for interactions with blood is given with the rationale for selection of tests based on their intended use specified, however, the specific testing protocols may vary significantly when performing the hemocompatibility assays. In recent years, medical catheters have been widely used in clinical practice. Moreover, a lot of surface modified catheters emerged in the market to enhance their performance of hemocompatibility especially for hydrophilic coating catheters. Unfortunately, to date, the hemocompatibility of hydrophilic coating still remains controversial due to the inherent complexity of the hemocompatibility test itself and lack of validated test methods. In this study, through determining the hemocompatibility performance for a micro-catheter with a typical hydrophilic pyrrolidone coating regarding haemolysis test, partial thromboplastin time (PTT), prothrombin time (PT) and thrombogenicity test in dogs, we have established a series of tentative hemocompatibility protocols for these tests. Hopefully, our study could not only provide some useful information for hemocompatibility evaluation on medical catheters with a hydrophilic coating but could also contribute to the development of neo-type hemocompatible medical devices for better clinical practice.

Hemocompatibility of biodegradable Zn-0.8 wt% (Cu, Mn, Li) alloys.

Zinc alloys have been explored as potential materials for biodegradable vascular stents due to their tolerable corrosion rates and tunable mechanical properties. However, the performances of Zn alloys were not supported with enough toxicity or biological compatibility evaluation, particularly hemocompatibility for vascular scaffolding application. In this work, the hemocompatibility of three zinc alloys (Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li) was evaluated with 316 L stainless steel and pure zinc as controls. The hemolysis ratios of 316 L stainless steel, pure Zn, Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li were 0.38 ±â€¯0.08%, 1.04 ±â€¯0.21%, 0.47 ±â€¯0.21%, 0.57 ±â€¯0.14% and 0.52 ±â€¯0.22%, respectively, for direct contact method. Platelets aggregation on the 316 L stainless steel was observed, while the adhered platelets on the Zn alloys exhibited round shape with few pseudopodia spreading. The number of adhered platelets on the three zinc alloys (Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li) had no statistically difference compared with 316 L stainless steel, while significant fewer than the pure Zn group. None remarkable platelet activation, hematocyte aggregation, coagulation or complement activation was observed in any Zn alloy group. Furthermore, the Zn alloys prolonged prothrombin time and partial thromboplastin time, demonstrating a potential function of anticoagulation. The results demonstrated that Zn alloys presented in this work are indeed meeting the hemocompatible requirements of implant and showing the promise for perspective application as biodegradable stent.

Strategy on biological evaluation for biodegradable/absorbable materials and medical devices.

During the last two decades, biodegradable/absorbable materials which have many benefits over conventional implants are being sought in clinical practices. However, to date, it still remains obscure for us to perform full physic-chemical characterization and biological risk assessment for these materials and related devices due to their complex design and coherent processing. In this review, based on the art of knowledge for biodegradable/absorbable materials and biological risk assessment, we demonstrated some promising strategies to establish and improve the current biological evaluation systems for these biodegradable/absorbable materials and related medical devices.