Artificial Blood Vessels Research Articles

Multiwavelength tissue-mimicking phantoms with tunable vessel pulsation

For the development and routine characterization of optical devices used in medicine, tissue-equivalent phantoms mimicking a broad spectrum of human skin properties are indispensable. Our work aims to develop a tissue-equivalent phantom suitable for photoplethysmography applications. The phantom includes the optical and mechanical properties of the three uppermost human skin layers (dermis, epidermis, and hypodermis, each containing different types of blood vessels) plus the ability to mimic pulsation. While the mechanical properties of the polydimethylsiloxane base material are adjusted by different mixing ratios of a base and curing agent, the optical properties are tuned by adding titanium dioxide particles, India ink, and synthetic melanin in different concentrations. The layered structure of the phantom is realized using a doctor blade technique, and blood vessels are fabricated using molding wires of different diameters. The tissue-mimicking phantom is then integrated into an artificial circulatory system employing piezo-actuated double diaphragm pumps for testing. The optical and mechanical properties of human skin were successfully replicated. The diameter of the artificial blood vessels is linearly dependent on pump actuation, and the time-dependent expansion profile of real pulse forms were mimicked. A tissue equivalent phantom suitable for the ex-vivo testing of opto-medical devices was demonstrated.

Resealable Antithrombotic Artificial Vascular Graft Integrated with a Self-Healing Blood Flow Sensor.

Coronary artery bypass grafting is commonly used to treat cardiovascular diseases by replacing blocked blood vessels with autologous or artificial blood vessels. Nevertheless, the availability of autologous vessels in infants and the elderly and low long-term patency rate of grafts hinder extensive application of autologous vessels in clinical practice. The biological and mechanical properties of the resealable antithrombotic artificial vascular graft (RAAVG) fabricated herein, comprising a bioelectronic conduit based on a tough self-healing polymer (T-SHP) and a lubricious inner coating, match with the functions of autologous blood vessels. The self-healing and elastic properties of the T-SHP confer resistance against mechanical stimuli and promote conformal sealing of suturing regions, thereby preventing leakage (stable fixation under a strain of 50%). The inner layer of the RAAVG presents antibiofouling properties against blood cells and proteins, and antithrombotic properties, owing to its lubricious coating. Moreover, the blood-flow sensor fabricated using the T-SHP and carbon nanotubes is seamlessly integrated into the RAAVG via self-healing and allows highly sensitive monitoring of blood flow at low and high flow rates (10- and 100 mL min-1, respectively). Biocompatibility and feasibility of RAAVG as an artificial graft were demonstrated via ex vivo, and in vivo experiment using a rodent model. The use of RAAVGs to replace blocked blood vessels can improve the long-term patency rate of coronary artery bypass grafts.

A 3D printing mold method for rapid fabrication of artificial blood vessels

A 3D printing mold method for rapid fabrication of artificial blood vessels

Effect of V-Shaped Groove Microstructure on Blood Flow Resistance in Bionic Artificial Blood Vessels

This study aims to investigate the blood flow in bionic artificial blood vessels and to reduce the resistance to blood flow, the drag reduction characteristics of V-shaped groove drag reduction microstructures in artificial blood vessel structures were investigated in depth. By varying the parameters of incoming flow velocity, groove width, and groove depth, the effect of various variable conditions on the drag reduction effect of the grooves was investigated, and the flow field characteristics and drag reduction effect of the V-shaped groove microstructure in the artificial blood vessel were obtained. A detailed analysis of the effect of velocity and groove size on the drag reduction effect of the groove was also carried out to demonstrate the drag reduction mechanism of the V-shaped groove microstructure and to summarize the variation law of the drag reduction rate of the V-shaped groove. The results show that the resistance reduction rate of the V-shaped groove microstructure decreases with the increase of blood flow velocity, increases with the increase of groove width, and increases and then decreases with the increase of groove depth. The velocity range used in this paper is 0.3–0.6 m/s, the groove width varies from 0 to 0.3 mm, and the groove depth varies from 0 to 0.3 mm.

Immediate Angioscopic Investigation After Cerebral Artery Thrombectomy Revealed Aortogenic Cerebral Infarction

Background Aortogenic embolism is one of the causes of embolic stroke of undetermined source, which can be difficult to diagnose. Methods We present the case of a 74‐year‐old male patient with a history of Bentall surgery and thoracic endovascular aortic repair who was transported to our hospital with sudden‐onset right‐sided hemiplegia and total aphasia. Magnetic resonance imaging revealed an acute left middle cerebral artery occlusion. Subsequently, an emergency mechanical thrombectomy was performed, through which the left middle cerebral artery was partially reperfused. We immediately investigated the aorta using an angioscopy. Results The angioscopy revealed a thrombus attached to an artificial blood vessel of the aorta close to the origin of the left common carotid artery. Because no other source of the embolus could be identified using electrocardiography or ultrasound, we diagnosed an aortogenic cerebral infarction by combining these findings with the pathological findings of the collected thrombus. Conclusions This is the first report that aortogenic cerebral infarction could be diagnosed using an angioscopy immediately after a cerebral artery thrombectomy.

Vascular cells responses to controlled surface structure and properties of bacterial nanocellulose artificial blood vessel after mercerization

Therapeutic benefits of small caliber artificial blood vessels to cure cardio and cerebrovascular diseases are mainly limited by their low patency during long-term transplantation. Bacterial nanocellulose (BNC), as a natural polysaccharide mainly synthesized by a bacterium Komagataeibatacter xylinus, has shown great potential in small-caliber vascular graft applications due to its shape controllability, and furthermore its physical surface structure can be adjusted with different treatments. However, influences of physical surface structure and properties of BNC conduits on behaviors of vascular cells have not been investigated. In this work, mercerized BNC conduits (MBNC) with different surface roughness and stiffness were constructed by controlled alkali (NaOH) treatment. The changes of surface structures and properties significantly affected the behaviors of vascular cells and gene expression; meanwhile, the cell seeding density also affected the cell responses. After mercerization with NaOH concentration > 10 %, it was observed that the increased stiffness of MBNC decreased several functional gene expressions of human vascular endothelial cells, and the pathological transformation of smooth muscle cells was inhibited. This study demonstrates physical surface structure of MBNC conduits will critically regulate functions and behaviors of vascular cells and it also provides important designing parameters to improve the long-term patency of BNC-based conduits.

Peptides-tethered vascular grafts enable blood vessel regeneration via endogenous cell recruitment and neovascularization

Cardiovascular injuries cause huge morbidity and mortality worldwide. Arterial reconstructions are generally performed either by using native grafts or synthetic grafts, both of which are limited by several complications. Synthetic biodegradable polymers offer a promising platform, which may also be modified to foster in situ tissue regeneration through the recruitment of host cells. Vascular endothelial growth factor (VEGF) promotes endothelialization and neovascularization in vascular grafts, however, an overdose of VEGF may induce tumor-like vasculature, which requires alternative strategies. The objective of this study was to exploit prominin-1-derived VEGF-binding peptide (BP) to improve neovascularization and endothelialization, while stromal cell-derived factor 1-alpha (SDF-1α) peptide to encourage endogenous stem/progenitor cells mobilization and complement BP-mediated vascular remodeling. The BP and SDF-1α peptides were covalently conjugated with low molecular weight poly (ε-caprolactone) (LPCL) to afford LPCL-BP and LPCL-SDF-1α, respectively. Chemical analysis revealed successful modification of LPCL with peptides, which also displayed good cytocompatibility in vitro once blended along with high molecular weight PCL (HPCL). The bioactived vascular grafts were fabricated by blending LPCL-BP, LPCL-SDF-1α or dual peptide-polymer conjugates with HPCL. The in vivo tests of vascular grafts through rat abdominal aorta implantation model revealed that, compared with HPCL grafts, the dual peptides modified grafts exhibited superior patency and tissue regeneration at 4-week post-implantation, including stem cell recruitment, rapid endothelialization and functional SMC layer formation. Taken together, these results may have implications for the in situ regeneration of artificial blood vessels through the orchestration of host's responses and endogenous cell recruitment.

Experimental Investigation of Temperature Influence on Nanoparticle Adhesion in an Artificial Blood Vessel.

A good understanding of the adhesion behaviors of the nanocarriers in microvessels in chemo-hyperthermia synergistic therapy is conducive to nanocarrier design for targeted drug delivery. In this study, we constructed an artificial blood vessel system using gelatins with a complete endothelial monolayer formed on the inner vessel wall. The numbers of adhered NPs under different conditions were measured, as well as the interaction forces between the arginine-glycine-aspartic acid (RGD) ligands and endothelial cells. The experimental results on the adhesion of ligand-coated nanoparticles (NPs) with different sizes and morphologies in the blood vessel verified that the gelatin-based artificial vessel possessed good cytocompatibility and mechanical properties, which are suitable for the investigation on NP adhesion characteristics in microvessels. When the temperature deviated from 37 °C, an increase or decrease in temperature resulted in a decrease in the number of adhered NPs, but the margination probability of NP adhesion increased at high temperatures due to the enhanced Brownian movement and flow disturbance. It is found that the effect of cooling was less than that of heating according to the observed changes in cell morphology and a decrease in cell activity under the static and perfusion culture conditions within the temperature range of 25 °C-43 °C. Furthermore, the measurement results of change in the RGD ligand-cell interaction with temperature showed good agreement with those in the number of adhered NPs. The Findings suggest that designing ligands that can bind to the receptor and are least susceptible to temperature variation can be an effective means to enhance drug retention.

Steerable catheter based on wire-driven seamless artificial blood vessel tube for endoscopic retrograde transpapillary interventions.

Current steerable catheters (SCs) for endoscopic retrograde cholangiopancreatography (ERCP) have performance limitations caused by an asymmetric multiple-slit tube design with a small maximum bend angle, lesser curvatures, and insufficient durability. We propose a wire-driven SC for balanced bidirectional bending using artificial blood vessel material to overcome these limitations. We assess the SC prototype's steerability using phantom and animal models. The SC prototype employed a slit-less and multiple-lumen seamless tube with a polytetrafluoroethylene (PTFE) body with stretch-retractable porous expanded PTFE at the distal end, and loop-formed control wires. We evaluated the wire routing design using a static model. The bending performance was compared with conventional SCs. Feasibility studies were performed, including major duodenal papilla insertions and ductal branch selections in desktop phantoms and a mini-pig model. The proposed design reduced the wire contact force by 48% compared to the single wire configuration. The maximum bend angle was 162°, almost twofold larger than that for conventional SCs. The lateral tip position in the bent shape was maximally 56% smaller. The tip flexibility was comparable to conventional SCs, and the insertion resistance was similar to the passive catheters. Phantom studies showed that the SC prototype could perform the large and protuberant papilla insertions and fine ductal branch selections without breaking; the animal study was completed successfully. We propose a wire-driven SC design for ERCP using a multi-lumen seamless tube and two loop-formed control wires, different from the conventional SC design with a multiple-slit tube and single control wire. The SC prototype records balanced bidirectional bending with a maximum bending angle of ± 162° without breakage risk. The phantom and animal studies show that the prototype performance potentially facilitates papilla cannulations and intrahepatic ductal branch seeking.

Rapid formation of ultrahigh strength vascular graft: Prolonging clotting time micro-dimension hollow vessels with interpenetrating polymer networks

Cardiovascular disease is the biggest killer of human health, and reliable small diameter artificial blood vessels still remains a huge challenge. During the transplant process, small-diameter artificial blood vessels need to meet the mechanical properties of physiological environment. The blood flow volume at the transplant site is often too small to wash away the microthrombi on the vessel wall. Therefore, small-diameter artificial blood vessels are required to have a prominent anticoagulant effect. In order to realize these expectations for small diameter artificial blood vessels, we successfully developed a micro diameter (diameter = 1.5 mm) vessel with polyvinyl alcohol (PVA) and alginate (Alg) interpenetrating polymer networks (IPN) through coaxial printing. The artificial blood vessel not only shows extreme high strength, but also can simulate the vascular compliance of natural blood vessel to overcome the lack of compliance of polymer artificial blood vessel. Due to the hydrophilicity of the material, the absorption ratio of albumin/fibrin was increased. It reduces the effect of the material on platelet activation and improves the anticoagulation of the material. The artificial vessels show excellent anticoagulation when tested from in vitro to ex vivo. The artificial blood vessels could grow closely with surrounding tissues after implantation in subcutaneous tissue on the back of a rat. The artificial blood vessel can well adapt to the needs of the graft site, and promote development of micro diameter artificial blood vessel.

Effect of surface structure on the antithrombogenicity performance of poly(-caprolactone)-cellulose acetate small-diameter tubular scaffolds

Small-diameter artificial blood vessels have always faced the problem of thrombosis. In this research, three types of poly(-caprolactone)-cellulose acetate (PCL-CA) composite nanofiber membranes were prepared by various collectors to make into a tubular scaffold with a 4.5-mm diameter. The collector consisted of two sizes of stainless steel wire mesh large-mesh (LM) and small-mesh (SM), respectively. There is also a random flat (RF) that acts as the third type collector. The nanofiber membrane's surface structure mimicked the collectors' surface morphology, they named LM, SM and RF scaffolds. The water contact angles of RF and LM scaffolds are 126.5° and 105.5°, and the distinct square-groove construction greatly improves the contact angle of LM. The tubular scaffolds' radial mechanical property test demonstrated that the large-mesh (LM) tubular scaffold enhanced the strain and tensile strength; the tensile strength and strain are 30 % and 148 % higher than that of the random-flat (RF) tubular scaffold, respectively. The suture retention strength value of the LM tubular scaffold was 103 % higher than that of the RF tubular scaffold. The cytotoxicity and antithrombogenicity performance were also evaluated, the LM tubular scaffold has 88 % cell viability, and the 5-min blood coagulation index (BCI) value was 89 %, which is much higher than other tubular scaffolds. The findings indicate that changing the tubular scaffold's surface morphology cannot only enhance the mechanical and hydrophilic properties but also increase cell survival and antithrombogenicity performance. Thus, the development of a small-diameter artificial blood vessel will be a big step toward solving the problem on thrombosis. Furthermore, artificial blood vessel is expected to be a candidate material for biomedical applications.

Expanded polytetrafluoroethylene/poly(3-hydroxybutyrate) (ePTFE/PHB) triboelectric nanogenerators and their potential applications as self-powered and sensing vascular grafts

Being able to detect or monitor the onset of thrombosis, recurrent stenosis, or other vascular disorders in newly transplanted vascular grafts will be very beneficial for patients who received the artificial blood vessel through bypass surgeries. The inherent advantages of triboelectric nanogenerators (TENGs) in self-powered signal monitoring presents a feasible solution. In this study, a double-layer TENG intended for self-powered and real-time sensing of vascular graft applications was constructed using two biocompatible materials commonly used in tissue engineering. In particular, an electrospun poly(3-hydroxybutyrate) (PHB) membrane as a positive tribomaterial was combined with an expanded polytetrafluoroethylene (ePTFE) membrane, a strong negative tribomaterial, to construct an ePTFE/PHB TENG. While possessing power generation, charging capacities, and operation stability, the ePTFE/PHB TENG was capable of supporting the growth of human umbilical vein endothelial cells (HUVECs) and monitoring changing hemodynamic conditions. Although many challenges remain and necessary future developments are needed, this study demonstrated the feasibility of a self-powered and sensing TENG vascular graft.

Single-Center Experience of Treating Chronic Limb-Threatening Ischemia of Lower Limbs Combined with Diabetes

To summarize our hospital's single-center experience of and reflections on the treatment of chronic limb-threatening ischemia (CLTI) of lower limbs combined with diabetes in the past 5 years. We retrospectively analyzed cases of lower limb CLTI combined with diabetes diagnosed at our hospital from March 2017 to June 2021. The baseline data, surgical information, and follow-up results of the patients were collected. The primary outcome indicator was the patency rate of lower limb target artery within 1 year post-op, and the secondary indicators were the reoperation rate within 1 year post-op and the amputation rate within 1 year post-op. A total of 89 patients with lower limb CLTI combined with diabetes were included in the study. A total of 85 patients underwent percutaneous transluminal angioplasty and the operation of 7 patients ended in failure, with the operation success rate reaching 91.76% (78/85). Three patients underwent femoral popliteal artery bypass grafting with artificial blood vessels and one patient underwent iliac femoral artery bypass grafting with artificial blood vessels, with the success rate of the operations reachign 100% (4/4). Among 78 patients who successfully underwent percutaneous transluminal angioplasty, the median follow-up time was 33 months (13, 64). Two patients died within one year after operation, with the post-op one-year survival rate being 97.44% (76/78). The post-op 1-year reoperation rate was 19.23% (15/78), the 1-year target vascular patency rate (deaths not included) was 85.53% (65/76), and the 1-year amputation rate was 3.85% (3/78). Among the patients who underwent bypass surgery, the follow-up period was 13-48 months. No thrombosis in or re-occlusion of the artificial blood vessels were observed during the follow-up period, and the artificial blood vessels remained unoccluded. Transluminal angioplasty has a relatively ideal rate of postoperative vascular patency. In addition, it is a minimally invasive procedure involving low perioperative risks and is performed under local anesthesia. Therefore, it can be used as the preferred treatment for patients with CLTI. On the other hand, bypass surgery has good long-term patency rate, but it involves higher perioperative risks and the procedure is more invasive. Therefore, bypass surgery can be used as an alternative when transluminal angioplasty ends in failure.

Application of branch-first technique in total thoracic aorta replacement: short and medium term effect of 11 cases

Objective: To examine the short and medium term effect of branch-first technique in total thoracic aorta replacement. Methods: The clinical data of eleven patients with ascending aortic aneurysms or type A aortic dissection+Crawford Ⅰ or Ⅱ total thoracoabdominal aortic aneurysm who were treated at Department of Cardiovascular Surgery in Henan Province Chest Hospital from January 2018 to July 2021 were retrospectively analyzed. There were 7 males and 4 females, aging (38±5) years (range: 28 to 45 years), 7 cases of whom were diagnosed with Marfan syndrome, 1 case was diagnosed with coarctation of aorta. Operations were performed under mild hypothermic and branch-first technique. Firstly, the middle and small incision in the chest was combined with the 6th intercostal incision in the left posterior lateral side. Secondly, four branches artificial blood vessels were anastomosed with the brachiocephalic artery to ensure the blood supply to the brain. After the circulation was blocked, intracardiac and aortic proximal operations were performed. Intercostal artery reconstruction and thoracic descending aorta replacement were completed after opening circulation. Results: The operative time of this group was (645.9±91.7) minutes (range: 505 to 840 minutes). One case had cerebral infarction and 1 case had chylothorax. The patients were followed up 4 to 47 months, 1 patient underwent thoracic and abdominal aorta+iliac artery resection and replacement due to the progression of abdominal aortic aneurysm 3 months after operation. Intercostal artery obstruction occurred in 2 cases, and the rest lived well. Conclusions: One-stage whole thoracic aorta replacement with branch-first technique has satisfactory results in the short and medium term, with no risk of residual aortic aneurysm rupture. It is an effective treatment for young and organs function well patients with complex aortic lesions.

Evaluation of electrospun PCL diol-based elastomer fibers as a beneficial matrix for vascular tissue engineering

The main reason for the failure of artificial blood vessel transplantation is the lack of mechanically matched materials with excellent blood compatibility. The electrospun biodegradable polyurethane (BPU) fibers with micro to nanoscale topography and high porosity similar to the natural extracellular matrix (ECM) is one of the most suitable options for vascular graft. In our recent study, we prepared a series of PCL-based BPU fibers by combining two-step solution polymerization and electrospinning. SEM, 1H NMR, ATR-FTIR, XRD, TG, water contact angle, and mechanical tests were used to analyze the chemical structure, microstructure, thermal properties, surface wettability, degradation, cytocompatibility, and hemocompatibility in vitro of electrospun fibers. The results show that the synthesized H-PEUU, L-PEUU, H-PEEUU, and L-PEEUU have different crystalline properties, thus exhibiting distinctive thermal, mechanical, and degradation properties. Although the existence of the molecular structure of LDI and PEG600 in fibers can promote cell proliferation and migration unilaterally, the microstructure of the material is also the main factor affecting the biocompatibility of cells. The results suggest that the designed PCL-based degradable polyurethane electrospun fiber is expected to be applied to vascular tissue engineering.

Potential of a Composite Conduit with Bacterial Nanocellulose and Fish Gelatin for Application as Small-Diameter Artificial Blood Vessel.

Bacterial nanocellulose (BNC) has received great attention for application as an artificial blood vessel material. However, many results showed that pristine BNC could not perfectly meet all the demands of blood vessels, especially for rapid endothelialization. In order to improve the properties of small-caliber vessels, different concentrations of fish gelatin (Gel) were deposited into the 3D network tubes and their properties were explored. The BNC/Gel composite tubes were treated with glutaraldehyde to crosslink BNC and fish gelatin. Compared with pristine BNC tubes, the BNC/Gel tubes had a certain improvement in mechanical properties. In vitro cell culture demonstrated that the human endothelial cells (HUVECs) and human smooth muscle cells (HSMCs) planted on the internal walls of BNC/Gel tubes showed better adhesion, higher proliferation and differentiation potential, and a better anticoagulation property, as compared to the cells cultured on pristine BNC tubes. Whole-blood coagulation experiments showed that the BNC/Gel tube had better properties than the BNC tube, and the hemolysis rate of all samples was less than 1.0%, satisfying the international standards for medical materials. An increase in the content of fish gelatin also increased the mechanical properties and the biocompatibility of small-caliber vessels. Considering the properties of BNC/Gel tubes, 1.0 wt/v% was selected as the most appropriate concentration of fish gelatin for a composite.

Validating a simulation model for laser-induced thermotherapy using MR thermometry

Objectives We want to investigate whether temperature measurements obtained from MR thermometry are accurate and reliable enough to aid the development and validation of simulation models for Laser-induced interstitial thermotherapy (LITT). Methods Laser-induced interstitial thermotherapy (LITT) is applied to ex-vivo porcine livers. An artificial blood vessel is used to study the cooling effect of large blood vessels in proximity to the ablation zone. The experimental setting is simulated using a model based on partial differential equations (PDEs) for temperature, radiation, and tissue damage. The simulated temperature distributions are compared to temperature data obtained from MR thermometry. Results The overall agreement between measurement and simulation is good for two of our four test cases, while for the remaining cases drift problems with the thermometry data have been an issue. At higher temperatures local deviations between simulation and measurement occur in close proximity to the laser applicator and the vessel. This suggests that certain aspects of the model may need some refinement. Conclusion Thermometry data is well-suited for aiding the development of simulations models since it shows where refinements are necessary and enables the validation of such models.

Embolization of Aortopulmonary Collateral Artery Cooperate with Valved Conduit Attached to the Right Ventricular Outflow Tract for Patient After Tetralogy of Fallot Repair: A One-Stop Procedure.

We describe a one-stop procedure for aortopulmonary collateral artery (APCA) and postoperative complications of Tetralogy of Fallot (TOF). Postoperative complications of TOF include right ventricular outflow tract stenosis, pulmonary valvular annular stenosis, pulmonary regurgitation, and aortopulmonary artery stenosis. The one-stop procedure was defined as after APCA embolization. The heart continued to function under cardiopulmonary bypass during median sternotomy to reconstruct the right ventricular outflow tract with a valved conduit and replace the aortopulmonary artery. A biological valved was sewed within the valved conduit in an artificial blood vessel in vitro and subsequently was used in the procedure and achieved significant results.

A Case of Superior Mesenteric Vein Aneurysm Treated with Artificial Blood Vessel Replacement

A Case of Superior Mesenteric Vein Aneurysm Treated with Artificial Blood Vessel Replacement

Multiaxis printing method for bent tubular structured gels in support bath for achieving high dimension and shape accuracy

Gels are soft materials that have high potential for use as alternative artificial blood vessels. 3D gel printing has attracted attention because it can be used to create gels with arbitrary and complicated shapes. The conventional 3D gel printing process (triaxial printing) is as follows: ⅰ) a sol material is patterned to form a layer on the XY plane, ⅱ) a crosslinker is added to it, ⅲ) the Z stage is lowered by the stacking pitch, and ⅳ) a new sol material is patterned on the previous layer. However, irregular protrusions and stepped structures appear at the overhang parts as the height and scale increase. In addition, there are non-adhesion sections between adjacent layers. To solve these problems, we propose a “multiaxis printing method,” in which layers are seamlessly stacked by changing the extruding direction by following the neutral line of a structure. We evaluate the dimension and shape accuracy of the proposed method by printing bent hollow tubular structured gels. The proposed method significantly suppresses irregular protrusions on outer walls. Moreover, each layer is seamlessly joined. The structures printed using the proposed method show good dimension and shape accuracy. The minimum lumen area ratio is 75%, which is comparable to native common carotid arteries. In addition, the maximum errors in the bending angle and curvature radius are 1.7% and 5.1%, respectively. However, the average outer and inner diameters are smaller than the patterning diameter, suggesting that the crosslinked gels attract each other in the circumferential direction. This indicates that a model should be designed considering gel shrinkage to further improve the accuracy of printing.