PDMS microchip coated with polydopamine/gold nanoparticles hybrid for efficient electrophoresis separation of amino acids.

In this paper, a novel, simple, economical and environmentally friendly method based on in situ chemically induced synthesis strategy was designed and developed for the modification of a poly(dimethylsiloxane) (PDMS) microchip channel with polydopamine/gold nanoparticles (PDA/Au NPs) to create a hydrophilic and biofouling resistant surface. Dopamine as a reductant and a monomer, and HAuCl(4) as an oxidant to trigger dopamine polymerization and the source of metallic nanoparticles, were filled into the PDMS microchannel to yield in situ a well-distributed and robust PDA/Au NP coating. Au NPs were highly and uniformly dispersed in/on the PDA matrix with a narrow size distribution, as verified by scanning electron microscopy and UV-vis spectra. Compared with the native PDMS microchannel, the modified surfaces exhibited much better wettability, high stability and suppressed electroosmotic mobility, and less nonspecific adsorption towards biomolecules. The water contact angle and EOF of PDA/Au NP-coated PDMS microchip were measured to be 13° and 4.17×10(-4) cm(2)/V s, compared to those of 111° and 5.33×10(-4) cm(2)/V s from the native one, respectively. Fast and efficient separations of five amino acids such as arginine, proline, histidine, valine and threonine suggested greatly improved electrophoretic performance of the PDA/Au NP-functionalized PDMS microchips. This one-step procedure offers an effective approach for a biomimetic surface design on microfluidic chips, which is promising in high-throughput and complex biological analysis.

[Department of a finite element model of the Head Model of HYBRID III Dummy with the Human Mandible].

OBJECTIVE: To analyze the biomechanics of impact injury in the condition of the simulate impact on mandible. METHODS: A finite element model of human mandible was developed from the CT scan images by the technologies of three-dimensional reconstruction, image processing and meshing. The mandible model was connected to a modified head model of HYBRID III dummy with joint according to the anatomic structure and mechanical characteristics of the temporomandibular joint. RESULTS: A finite element model of human head with true anatomic structure mandible has been developed. This model has been validated with the cadaver test results. The higher stress was showed in the condyle rejoins and coracoid in the model when mandible was in impact simulation. CONCLUSIONS: This model can be used to research the mechanism of craniofacial blunt-impact injury and assess the injury severity. The model of HYBRID III dummy with the human mandible was helpful for the boundary design of mandibular model in the impact simulations.

Facile preparation of protein stationary phase based on polydopamine/graphene oxide platform for chip-based open tubular capillary electrochromatography enantioseparation.

A novel chip-based enantioselective open-tubular capillary electrochromatography (OT-CEC) was developed employing bovine serum albumin (BSA) conjugated polydopamine-graphene oxide (PDA/GO) nanocomposites (PDA/GO/BSA) as stationary phase. After the poly(dimethylsiloxane) (PDMS) microfluidic chip was filled with a freshly prepared solution containing dopamine and graphene oxide, PDA/GO nanocomposites were formed and deposited on the inner wall of microchannel as permanent coating via the oxidation of dopamine by the oxygen dissolved in the solution. The PDA/GO-coated PDMS microchips not only have the adhesion of PDA that make them easily immobilized in the microchannel, but also have the larger surface and excellent biocompatibility of graphene which can incorporate much more biomolecules and well maintain their biological activity. In addition, incorporation of GO in PDA film can make surface morphology more rough, which is beneficial for enhancing the loading capacity of proteins in the microchannels and increasing sample capacity of OT-CEC columns. BSA was stably immobilized in the PDMS microchannel to fabricate a protein-stationary phase. Compared with the native PDMS microchannels, the modified surfaces exhibited much better wettability, more stable electroosmotic mobility, and less nonspecific adsorption. The efficient separation of chiral amino acids (tryptophan and threonine) and chiral dipeptide demonstrate that the constructed OT-CEC columns own ideal enantioselectivity. The presented strategy using PDA/GO coating as a versatile platform for facile conjugation of proteins may offer new processing strategies to prepare a functional surface designed on microfluidic chips.

[Mandibular-driven simultaneous maxillo-mandibular distraction for hemifacial microsomia with rapid prototyping technology].

OBJECTIVE: To explore the clinical application of mandibular-driven simultaneous maxillo-mandihular distraction to correct hemifacial microsomia with rapid prototyping technology. METHODS: The patient' s skull resin model was manufactured with rapid prototyping technology. The osteotomy was designed on skull resin model. According to the preoperative design, the patients underwent Le Fort I osteotomy and mandibular ramus osteotomy. The internal mandible distractor was embedded onto the osteotomy position. The occlusal titanium pin was implanted. Distraction were carried out by mandibular-driven simultaneous maxillo-mandihular distraction 5 days after operation. RESULTS: The distraction in five patients was complete as designed. No infection and dysosteogenesis happened. The longest distance of distraction was 28 mm, and the shortest distance was 16 mm. The facial asymmetry deformity was significantly improved at the end of distraction. The ocelusal plane of patients obviously improved. CONCLUSIONS: Rapid prototyping technology is helpful to design precisely osteotomy before operation. Mandibular-driven simultaneous maxillo-mandibular distraction can correct hemifacial microsomia. It is worth to clinical application.

A versatile polydopamine platform for facile preparation of protein stationary phase for chip-based open tubular capillary electrochromatography enantioseparation.

A novel, simple, and economical method for the preparation of chiral stationary phases for chip-based enantioselective open tubular capillary electrochromatography (OT-CEC) using polydopamine (PDA) coating as an adhesive layer was reported for the first time. After the poly(dimethylsiloxane) (PDMS) microfluidic chip was filled with dopamine (DA) solution, PDA film was gradually formed and deposited on the inner wall of microchannel as permanent coating via the oxidation of DA by the oxygen dissolved in the solution. Due to possessing plentiful catechol and amine functional groups, PDA coating can serve as a versatile multifunctional platform for further secondary reactions, leading to tailoring of the coatings for protein bioconjugation by the thiols and amines via Michael addition or Schiff base reactions. Bovine serum albumin (BSA), acting as a target protein, was then stably and homogeneously immobilized in the PDA-coated PDMS microchannel to fabricate a novel protein stationary phase. Compared with the native PDMS microchannels, the modified surfaces exhibited much better wettability, more stable and enhanced electroosmotic mobility, and less nonspecific adsorption. The water contact angle and electroosmotic flow of PDA/BSA-coated PDMS substrate were measured to be 44° and 2.83×10(-4)cm(2)V(-1)s(-1), compared to those of 112° and 2.10×10(-4)cm(2)V(-1)s(-1) from the untreated one, respectively. Under a mild condition, d- and l-tryptophan were efficiently separated with a resolution of 1.68 within 130s utilizing a separation length of 37mm coupled with in-column amperometric detection on the PDA/BSA-coated PDMS microchips. This present versatile platform, facile conjugation of biomolecules onto microchip surfaces via mussel adhesive protein inspired coatings, may offer new processing strategies to prepare a biomimetic surface design on microfluidic chips, which is promising in high-throughput and complex biological analysis.

[Study of biomechanical properties of mucosa scars after cleft palate surgery].

OBJECTIVE: To explore biomechanical properties and stress-strain of mucosa scars after cleft palate surgery. METHODS: After the model of mucosa scars was made, the mucosa scars and normal mucosa were excised and examined immediately by tensionometry. RESULTS: The mucosa scars after cleft palate surgery were compared with normal mucosa. The Poisson's ratio of mucosa scars and normal mucosa was 0.5 and 0.49, respectively, showing no significant difference between the two groups. The ultimate Young's modulus of mucosa scars was about 24.22 MPa, however, it declined to 3.32 Mpa in normal mucosa. CONCLUSIONS: The mucosa scars after cleft palate surgery are biomechanically weaker than normal mucosa. It can be used for further research, such as maxillary orthognathic surgery, distraction osteogenesis, and orthodontic treatment.

[Application of the cone beam computed tomography (CBCT) in Le Fort I osteotomy].

OBJECTIVE: To improve the accuracy and safety of the Le Fort I osteotomy. METHODS: Eighty-four patients underwent CBCT scan before maxillary orthognathic surgery. The anatomic structures of maxilla were marked and measured. RESULTS: In 84 cases, there were 3 cases with severe hypoplasia of maxillary sinus, 11 cases with impacted third molar, 8 cases with separation in maxillary sinus, 4 cases with the deviation of nasal septum, and 3 cases with cysts in maxillary sinus. Form CBCT images, the position of the pterygopalatine canal, the thickness of maxillary wall, hidden lesion of maxillary sinus, the location of Impacted molar, the deviation of nasal septum, and other anatomic structure could be accurately localized. CBCT could provide sufficient and valuable information in diagnosis and design for Le Fort I osteotomy. CONCLUSIONS: CBCT imaging technology could provide precise anatomic images for Le Fort I osteotomy. It improves the accuracy and safety of the Le Fort I osteotomy.

[Three-dimensional finite element analysis for external midface distraction after different osteotomy in patients with cleft lip and palate].

OBJECTIVE: To study three-dimensional finite element analysis for external midface distraction after different osteotomy in patients with cleft lip and palate (CLP). METHODS: Three-dimensional FEM models of Le Fort I, II and III osteotomy in CLP patients were established. External midface distraction were simulated. An anteriorly and inferiorly directed 900 g force was applied to bilateral maxillary arch in directions 30 degrees to the occlusal plane. Biomechanical changes for the maxillary complex were investigated by means of finite element analysis. RESULTS: Maxillary complex was advanced after different osteotomy. Constriction of alveolar crest and palate occurred in Le Fort I osteotomy, but not in Le Fort II and III osteotomy. Clockwise rotation occurred in Le Fort I osteotomy complex. Counterclockwise rotation occurred in Le Fort II and III osteotomy complex. CONCLUSIONS: Three-dimensional finite element research on external midface distraction could provide reference for the preoperative design.

[An ultrastructure study on the palatomaxillary suture of dog expanded by NiTi-SMA].

OBJECTIVE: To explore the ultrastructure of the palate-maxillary sutures under tensile forces by transmission electron microscope (TEM). METHODS: The Suture expanders were made in NiTi-Shape memory alloy (NiTi-SMA). The maximum force was 3.5 N. Fourteen 8-month old mongrel dogs were used in the study. They were divided into three groups, (1) experimental group, (2) control group, (3) sham group. In the experiment and control groups, an 8 mm wide cleft was made by surgery. The suture expanders were fixed onto the palatine bones of the experimental group. The dogs of the experimental group were executed after 3, 7, 14, 28, 56 days of suture expansion. The change of suture tissue was examined by TEM. RESULTS: The cleft of the experiment group were closed at the ninth day of expansion. At the beginning, tissue rupture, exudation, death of fibroblasts, disruption of collagen and tear vessels were seen at the early stage of suture expansion. Then highly active functional manifestations were seen in both osteocytic and fibrocytic populations. At last, normal structure restored. CONCLUSIONS: Cell types and functional condition could be distinguished clearly by TEM. It suggests that the suture expansion should be the process of tissue repair and regeneration. The suture cells response, especially, the osteogenic response were the major factor of increasing suture width.

[Three-dimensional finite element analysis for different directions distraction at midface].

OBJECTIVE: To investigate the biomechanical changes with different directions distraction at midface. METHODS: An anteriorly directed 500 g force was applied to the floor of apertura piriforms in different directions to the occlusal plane. Three-dimensional finite element analysis was used to evaluate the biomechanical change of craniofacial complex. RESULTS: As the force direction was moved downward, the sagittal distraction length of the craniofacial complex decreased and vertical movement changed from upward to downward. The craniofacial complex was moved anteriorly when the downward force was applied about 20-30 degrees to the occlusal plane. The forces could generate the uniform stress distribution in the craniofacial sutures and avoid counterclockwise rotation of the maxilla. CONCLUSIONS: The craniofacial complex can be effectively distracted anteriorly when the downward force is applied to the floor of aperture piriforms in direction of 20-30 degrees to the occlusal plane.

[Biomechanical study of internal midface distraction after different types of maxillary osteotomy in patients with cleft lip and palate].

OBJECTIVE: To investigate the biomechanical changes of internal midface distraction after different types of maxillary osteotomy in patients with cleft lip and palate (CLP). METHODS: 3-D finite element (FEM) analysis was used. 3-D models of Le Fort I, II, III osteotomy and soft tissue were established. Based on the new pattern of internal midface distractor, the distraction of maxillary complex was simulated to advance 10 mm anteriorly. The mechanical change was studied. RESULTS: The maxillary complex in CLP were advanced after distraction. Constriction of alveolar crest and palate occurred in Le Fort I osteotomy, but not in Le Fort II and III osteotomy. The maxillary complex was moved anteriorly en bloc after Le Fort III osteotomy, but some degree of rotation of maxillary complex was observed during the distraction after Le Fort I and II osteotomy. In vertical direction, the maxillary complex had more counterclockwise rotation after Le Fort II osteotomy. CONCLUSION: 3-D FEM analysis can be used for the study of internal distraction. It can reflect the maxillary movement and provide the theory basis for preoperative design.

[Application of thoracic skin flap with multiple blood supply in repair of tissue defects and deformities in jaw and neck].

OBJECTIVE: To explore an appropriate measure to repair tissue defects and deformities in mandibulo-cervical region. METHODS: Eighteen cases with severe tissue defects and deformity in jaw and neck were repaired with thoracic skin flap with multiple blood supply system in our unit from Jan. 2006 to Nov. 2008. Anterior cutaneous branch of transverse cervical artery, intercostal branch of internal thoracic artery and lateral thoracic artery were included in the pedicles. RESULTS: All skin flaps survived, except in one patient in whom a small belb appeared at the distal end of the island flap with anterior cutaneous branch of transverse cervical artery, and it was healed after a few dressing changes. The functions and appearances were satisfactory after 6-month to 2-year follow-up, without showing secondary deformity. CONCLUSIONS: The blood supply of thoracic skin flap is abundant and constant, which is an ideal method for repair of tissue defects and deformities in jaw and neck after taking into account some factors, such as the demand of the patient, general physical condition, and the size of the defect.

[Three-dimensional finite element analysis of craniofacial skeleton protraction at medium position].

OBJECTIVE: The purpose of this study was to investigate the biomechanical changes of midface skeleton protraction at its medium position in the craniofacial complex, using the three-dimensional finite element method (FEM). METHODS: A three-dimensional FEM model was developed from the CT scan images by the technologies of three-dimensional reconstruction, image processing and meshing. The protraction forces were applied to the following locations: the first molar, full maxillary arch, and the floor of aperture piriforms. Biomechanical changes from different position protraction were investigated by means of finite element analyses. RESULTS: Protraction forces at the level of the floor of aperture piriforms produced a more forward movement of the upper maxilla in sagittal direction. Vertical and lateral displacements were less than those in loading with teeth or denture. Compressive stress on the radix nasi decreased obviously in midface skeleton protraction at its medium position. CONCLUSIONS: Compared with traditional orthopedic protraction, midface skeleton protraction at its medium position could advance maxilla en bloc, decrease the counterclockwise rotation of the maxilla, and reduce the constriction of the anterior part of the palate.

[Establishment of the database of female skull by the aesthetics].

OBJECTIVE: The three-dimensional (3D) craniofacial measurements were studied through the quantitative computed tomography (CT). The dynamic database of quantitative measurement of three-dimensional craniofacial bone was established as mandible in physiological position. METHODS: 170 aesthetics female were examined by spiral volumetric CT (GE SR-7000). 3D craniofacial bone images were reformatted and 3D measurements were performed in SUN Workstation respectively. 33 points were defined in the 3-d craniofacial structure in screen, 14 distances and 11 angles were measured, and 12 ratios were calculated in each case. All data were transferred into the database based on the SPSS software. There is all information of one case (such as number, sex, age, distances, angers) in one row; each column is a measurement item. The mean, standard deviation, standard error, medium, coefficient of variation and 95% confidence interval of data can be calculated and the correlation, regression between several groups of measurement item can be proceeded by computer automatically in the dynamic database. RESULTS: 3D craniofacial bone imagings were displayed in arbitrary views without disturbing superposition by using cutting, rotating and 3D measurement procedures. The large data volume provides more information of special relationship of skull base, zygomatic bone, maxilla, mandible and vertebra. The coefficient of variation of skull base is less than them of maxilla and mandible. The standard deviation of ratios is further smaller than the standard deviation of distances and angles. With stepwise regression, the equation is (Go - Go) Y = 0.578X1 + 0.754X2 + 0.228X3 - 0.579X4 - 14.672; (Tz- Tz) : Y = 0.775X1 + 0.161X2 + 0.348X3 + 0.201X4 + 27.730. CONCLUSIONS: The database offers reference of the studying of growth rule of craniofacial bone of aesthetics female. It will help improve diagnostic accuracy, staging of reconstruction, precision of corrective surgery, and follow-up patients.

[Suppositional sutural construction and application in the three-dimensional finite element model of craniofacial complex].

OBJECTIVE: The purpose of this study was to explore suppositional sutural construction and protraction in the three-dimensional finite element model of craniofacial complex. METHODS: Combining spiral CT scanning technology with the three-dimensional finite element method, three-dimensional FEM model of craniofacial complex was developed for analysis. In the model, craniofacial sutures were constructed through the MSC. Patran program and different mechanical properties of sutures were applied. Under the same loading condition, bone displacements of the maxilla were calculated. RESULTS: A three-dimensional FE model of craniofacial complex, comprising teeth and craniofacial sutures, was developed. The displacement of the skeletal structures with sutures was significantly larger than that without sutures. CONCLUSIONS: The construction of craniofacial sutures in the three-dimensional finite element model of craniofacial complex could improve the accuracy of finite element model, which set up good foundation for biomechanical studies of craniofacial complex.

[Responses of dogs at different ages and long-term effects for midface skeleton protraction].

OBJECTIVE: To explore the factor of age related to protraction response. METHODS: Four 12-week mongrel dogs in the same nest were randomly assigned into two groups: the control (n = 1) and the experimental groups (n = 3). Four pairs of titanium bone markers were fixed on either side of the bone sutures of all animals. Distraction device was fitted in the experimental group, A forward elastic force was exerted through the device for 1 month. Midface skeleton protraction was applied to experimental group at different age. Dog 2 was started at 12 weeks of age. Dog 3 was started at 16 weeks of age. Dog 4 was started at 20 weeks of age. The protraction force was 600g. All the animals were sacrificed at their age of 9 months. The results were evaluated clinically, radiographically, and cephalometrically. RESULTS: All the animals in the experimental group showed progressively forward movement of the maxilla at the end of the experiment. In the same condition, the younger age appeared to have more effective in treatment than the older age. After 3 approximately 4 weeks stagnation, the maxilla gradually recovered normal growth. CONCLUSION: The younger age lead more effective protraction than the older age. Persistent elastic distraction at the medium position of midface brought stable effects and no influence on facial growth.

[Trans-sutural distraction osteogenesis for early correction of midfacial hypoplasia in children: a primary clinical report].

OBJECTIVE: To probe the possibility of trans-sutural distraction osteogenesis for correction of children midfacial hypoplasia. METHODS: The trans-sutural distraction system of mid-facial skeleton consisted of the bone-borne traction hooks of titanium, the face-bow, and the elastic loops. Nine children with midfacial hypoplasia were treated at their 6 - 12 years of age. No osteotomy was made in them. Bone holes were drilled with a dental bur at each side of the lateral-inferior rim of the aperture, or at the anterior part of the hard palate. The traction device was hatched to the holes through the nostrils. Protraction began 3 days postoperatively, with the forces adjusted dependently upon the rate of progress. When the skeleton reached to the planed position, it was retained with a minor force for 8 weeks. RESULTS: The mid-facial skeleton of the nine children showed a balanced advancement. Their facial profile and cross-bite were corrected satisfactory. CONCLUSIONS: Patients with severe mid-facial hypoplasia could be corrected ideally by the new technique, with minor trauma, easy manipulation. The design of protraction system was reasonable.

[The possibility of midface skeleton protraction: an experimental study in dogs].

OBJECTIVE: To probe the feasibility of a new technique of sutural distraction osteogenesis for midface hypoplasia repair. METHODS: A protraction system was developed, which consisted of three parts: a rigid external framework, a bone hook, and the elastic band. Four 12-week mongreal dogs were randomly assigned into two groups: the control (n = 1) and the experimental groups (n = 3). Four pairs of titanium bone markers were fixed on either side of the bone sutures of all animals. The experimental group was fitted with a distraction device, through which a forward elastic force was exerted for 1 month. Clinical observations and X-ray examinations were performed at the beginning and the end of distraction. New bone specimens were examined histologically. RESULTS: All the animals in the experimental group showed progressively forward movement of the maxilla and manifested class II occlusion at the end of the experiment. The distance increase between each pair of bone markers showed that premaxilla advancement was more than that of the maxilla. The next was zygoma. There was no obvious difference between the control and the experimental group in terms of the basilar-maxillary angle and counterclockwise rotation. Theer was active osteogenesis in the sutures, especially in premaxilla-maxillary sutures. The number of osteoblasts and fibroblasts increased dramatically and new bone formation was found at the edge of the suture. CONCLUSION: This technique can create effective advancement of the maxilla. The direct force can avoid counterclockwise rotation of the maxilla during distraction.

[Long-term effects and influence on facial structure of palatal distraction].

OBJECTIVE: The purpose of this study was to evaluate a new palatoplasty with persistent elastic distraction osteogenesis. METHODS: Twenty mongrel dog aged in 6 month were divided into two groups: the control (n = 10) and the experimental group (n = 10). The cleft palate model was made surgically in experimental dogs. The hard palate clefts were repaired with persistent elastic distraction osteogenesis. Then the animals were observed for an additional 12 weeks before sacrifice. Direct measurements was taken on dry skulls of the dogs and the data were analyzed statistically. RESULTS: For all experimental dogs, the clefts were closed after gradual distraction. No relapse and airway blocking occurred in observational period. There were no significant differences in the variables of facial length, height and width between the two groups (P > 0.05). The length of horizontal portion of hard palate in experimental group was significantly longer than that in the control (P < 0.01). CONCLUSION: There was no complication and disturbance on maxillofacial structure in repairing cleft palate with persistent elastic distraction osteogenesis. It is an effective and safe technique for repairing cleft palate in animal model.

[Sutural distraction osteogenesis for primary cleft palate repair: a preliminary clinical report].

OBJECTIVE: To probe the possibility of a new technique of primary cleft palate repair by sutural distraction osteogenesis. METHODS: The distractor was made of TiNi-shape memory alloy with 2 secure and 2 active arms. Under general anesthesia, 1 hole was drilled on each maxillary process and horizontal plate of palatine. The four arms of the distractor were inserted into holes. The palatine bones would then be distracted and moved medially and posteriorly. After 4 to 5 months' distraction, the two cleft edges approached gradually. The residual cleft, according to its width, was repaired by direct stitch of muco-periosteum incised at cleft edges, or with an additional relaxing incision on one side of the palate. Direct measurement of width of maxillary arch and the cleft, and the length of the hard palate was performed before and after distraction to evaluate the effects of distraction. RESULTS: Eight cleft children at their 2 to 4 years of age were treated by the new technique. Two of them terminated the procedure due to premature dislocation of the distractor. Six children underwent 37 to 126 days' distraction. Dramatic narrowing of the cleft and lengthening of hard palate were seen in these children, with the average narrowing of the cleft being 6.5 mm and average lengthening of the hard palate being 4.8 mm. CONCLUSION: It is clinically demonstrated that palatal tissue regeneration and cleft closure or narrowing and hard palate lengthening could be achieved by the technique of sutural distraction osteogenesis.