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Spider silk is recognized for its exceptional mechanical properties and biocompatibility, making it a versatile platform for developing functional materials. In this study, a modular functionalization strategy for recombinant spider silk is presented using SpyTag/SpyCatcher chemistry, a prototype of genetically encoded click chemistry. The approach involves AlphaFold2-aided design of SpyTagged spider silk coupled with bacterial expression and biomimetic spinning, enabling the decoration of silk with various SpyCatcher-fusion motifs, such as fluorescent proteins, enzymes, and cell-binding ligands. The silk threads can be coated with a silica layer using silicatein, an enzyme for silicification, resulting in a hybrid inorganic–organic 1D material. The threads installed with RGD or laminin cell-binding ligands lead to enhanced endothelial cell attachment and proliferation. These findings demonstrate a straightforward yet powerful approach to 1D protein materials., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., ImPhys/Maresca group

Spider silk is recognized for its exceptional mechanical properties and biocompatibility, making it a versatile platform for developing functional materials. In this study, a modular functionalization strategy for recombinant spider silk is presented using SpyTag/SpyCatcher chemistry, a prototype of genetically encoded click chemistry. The approach involves AlphaFold2-aided design of SpyTagged spider silk coupled with bacterial expression and biomimetic spinning, enabling the decoration of silk with various SpyCatcher-fusion motifs, such as fluorescent proteins, enzymes, and cell-binding ligands. The silk threads can be coated with a silica layer using silicatein, an enzyme for silicification, resulting in a hybrid inorganic–organic 1D material. The threads installed with RGD or laminin cell-binding ligands lead to enhanced endothelial cell attachment and proliferation. These findings demonstrate a straightforward yet powerful approach to 1D protein materials.

Although the tools based on split proteins have found broad applications, ranging from controlled biological signaling to advanced molecular architectures, many of them suffer from drawbacks such as background reassembly, low thermodynamic stability, and static structural features. Here, we present a chemically inducible protein assembly method enabled by the dissection of the carboxyl-terminal domain of a B12-dependent photoreceptor, CarHC. The resulting segments reassemble efficiently upon addition of cobalamin (AdoB12, MeB12, or CNB12). Photolysis of the cofactors such as AdoB12 and MeB12 further leads to stable protein adducts harboring a bis-His–ligated B12. Split CarHC enables the creation of a series of protein hydrogels, of which the mechanics can be either photostrengthened or photoweakened, depending on the type of B12. These materials are also well suited for three dimensional cell culturing. Together, this new protein chemistry, featuring negligible background autoassembly, stable conjugation, and phototunability, has opened up opportunities for designing smart materials.

Engineered living materials (ELMs) are gaining traction among synthetic biologists, as their emergent properties and nonequilibrium thermodynamics make them markedly different from traditional materials. However, the aspiration to directly use living cells as building blocks to create higher-order structures or materials, with no need for chemical modification, remains elusive to synthetic biologists. Here, we report a strategy that enables the assembly of engineered Saccharomyces cerevisiae into self-propagating ELMs via ultrahigh-affinity protein/protein interactions. These yeast cells have been genetically engineered to display the protein pairs SpyTag/SpyCatcher or CL7/Im7 on their surfaces, which enable their assembly into multicellular structures capable of further growth and proliferation. The assembly process can be controlled precisely via optical tweezers or microfluidics. Moreover, incorporation of functional motifs such as super uranyl-binding protein and mussel foot proteins via genetic programming rendered these materials suitable for uranium extraction from seawater and bioadhesion, respectively, pointing to their potential in chemical separation and biomedical applications.

Although the tools based on split proteins have found broad applications, ranging from controlled biological signaling to advanced molecular architectures, many of them suffer from drawbacks such as background reassembly, low thermodynamic stability, and static structural features. Here, we present a chemically inducible protein assembly method enabled by the dissection of the carboxyl-terminal domain of a B12-dependent photoreceptor, CarHC. The resulting segments reassemble efficiently upon addition of cobalamin (AdoB12, MeB12, or CNB12). Photolysis of the cofactors such as AdoB12 and MeB12 further leads to stable protein adducts harboring a bis-His–ligated B12. Split CarHC enables the creation of a series of protein hydrogels, of which the mechanics can be either photostrengthened or photoweakened, depending on the type of B12. These materials are also well suited for three dimensional cell culturing. Together, this new protein chemistry, featuring negligible background autoassembly, stable conjugation, and phototunability, has opened up opportunities for designing smart materials.

The peptide/protein pair, SpyTag/SpyCatcher, which is derived from split immunoglobulin-like collagen adhesin domain (CnaB2) from Streptococcus pyogenes, can spontaneously form a stable Lys-Asp isopeptide bond under physiological conditions. This enabling technology— also known as genetically encoded click chemistry owing to its marked efficiency and specificity—has led to a variety of applications in protein engineering, materials science and synthetic biology in recent years. In this chapter, we discuss the use of SpyTag/SpyCatcher chemistry to create nonlinear protein architectures and materials, with emphasis on its role in shaping up topology engineering as an emerging branch of protein engineering. The synthesis of entirely protein-based molecular networks, Spy networks, is highlighted. The protocols for preparing Spy networks and applications thereof are also illustrated. © 2020 Elsevier Inc.

The peptide/protein pair, SpyTag/SpyCatcher, which is derived from split immunoglobulin-like collagen adhesin domain (CnaB2) from Streptococcus pyogenes, can spontaneously form a stable Lys-Asp isopeptide bond under physiological conditions. This enabling technology— also known as genetically encoded click chemistry owing to its marked efficiency and specificity—has led to a variety of applications in protein engineering, materials science and synthetic biology in recent years. In this chapter, we discuss the use of SpyTag/SpyCatcher chemistry to create nonlinear protein architectures and materials, with emphasis on its role in shaping up topology engineering as an emerging branch of protein engineering. The synthesis of entirely protein-based molecular networks, Spy networks, is highlighted. The protocols for preparing Spy networks and applications thereof are also illustrated. © 2020 Elsevier Inc.

The peptide/protein pair, SpyTag/SpyCatcher, which is derived from split immunoglobulin-like collagen adhesin domain (CnaB2) from Streptococcus pyogenes, can spontaneously form a stable Lys-Asp isopeptide bond under physiological conditions. This enabling technology— also known as genetically encoded click chemistry owing to its marked efficiency and specificity—has led to a variety of applications in protein engineering, materials science and synthetic biology in recent years. In this chapter, we discuss the use of SpyTag/SpyCatcher chemistry to create nonlinear protein architectures and materials, with emphasis on its role in shaping up topology engineering as an emerging branch of protein engineering. The synthesis of entirely protein-based molecular networks, Spy networks, is highlighted. The protocols for preparing Spy networks and applications thereof are also illustrated. © 2020 Elsevier Inc.

Hydrogels, noted for their biomimetic properties, are the main materials used in biomedical applications such as drug delivery and stem cell therapy. Traditional hydrogels made up of either synthetic polymers or natural biomolecules often serve as passive scaffolds for molecular or cellular species. These features render traditional hydrogels unable to fully recapitulate biological dynamics. It is, therefore, increasingly important to design stimuli-responsive, dynamic hydrogels that can accommodate or mimic the complexity of biological systems. The properties of photoresponsive hydrogels can be controlled using light with great spatiotemporal precision. Although a great number of photoreceptors proteins have been discovered and engineered in the past few decades, which has further led to the emergence of powerful optogenetic tools for numerous biomedical research and applications, most photoresponsive materials still rely on synthetic chromophores as light-sensing moieties, leaving the diverse protein-based photoreceptors untapped. In this thesis, we developed a new category of protein-based photoresponsive hydrogels by combining the use of recombinant DNA technology, a robust protein assembly strategy known as SpyTag/SpyCatcher chemistry and the newly discovered protein photoreceptor CarH. In Chapter 2, we show the synthesis of the entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. Also shown is the resulting hydrogel that exhibited a rapid gel-sol transition on the light exposure. In Chapter 3, we demonstrate that the hydrogel composed of physically self-assembled CarHC polymers enabled the light-controlled facile release/recovery of human mesenchymal stem cells (hMSCs), 3T3 fibroblasts and PC12 cells f

We report the robust growth of an entirely protein-based, photo- and thermoresponsive Layer-by-Layer nanofilm using genetically encoded SpyTag/SpyCatcher chemistry. The process was facilitated by AdoB12-induced tetramerization of photoreceptor proteins. Protein cargos can be released from the film in a light-dependent manner, showing its potential for therapeutic protein delivery.

Hydrogels, noted for their biomimetic properties, are the main materials used in biomedical applications such as drug delivery and stem cell therapy. Traditional hydrogels made up of either synthetic polymers or natural biomolecules often serve as passive scaffolds for molecular or cellular species. These features render traditional hydrogels unable to fully recapitulate biological dynamics. It is, therefore, increasingly important to design stimuli-responsive, dynamic hydrogels that can accommodate or mimic the complexity of biological systems. The properties of photoresponsive hydrogels can be controlled using light with great spatiotemporal precision. Although a great number of photoreceptors proteins have been discovered and engineered in the past few decades, which has further led to the emergence of powerful optogenetic tools for numerous biomedical research and applications, most photoresponsive materials still rely on synthetic chromophores as light-sensing moieties, leaving the diverse protein-based photoreceptors untapped. In this thesis, we developed a new category of protein-based photoresponsive hydrogels by combining the use of recombinant DNA technology, a robust protein assembly strategy known as SpyTag/SpyCatcher chemistry and the newly discovered protein photoreceptor CarH. In Chapter 2, we show the synthesis of the entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. Also shown is the resulting hydrogel that exhibited a rapid gel-sol transition on the light exposure. In Chapter 3, we demonstrate that the hydrogel composed of physically self-assembled CarHC polymers enabled the light-controlled facile release/recovery of human mesenchymal stem cells (hMSCs), 3T3 fibroblasts and PC12 cells f

We report the robust growth of an entirely protein-based, photo- and thermoresponsive Layer-by-Layer nanofilm using genetically encoded SpyTag/SpyCatcher chemistry. The process was facilitated by AdoB12-induced tetramerization of photoreceptor proteins. Protein cargos can be released from the film in a light-dependent manner, showing its potential for therapeutic protein delivery.

Hydrogels, noted for their biomimetic properties, are the main materials used in biomedical applications such as drug delivery and stem cell therapy. Traditional hydrogels made up of either synthetic polymers or natural biomolecules often serve as passive scaffolds for molecular or cellular species. These features render traditional hydrogels unable to fully recapitulate biological dynamics. It is, therefore, increasingly important to design stimuli-responsive, dynamic hydrogels that can accommodate or mimic the complexity of biological systems. The properties of photoresponsive hydrogels can be controlled using light with great spatiotemporal precision. Although a great number of photoreceptors proteins have been discovered and engineered in the past few decades, which has further led to the emergence of powerful optogenetic tools for numerous biomedical research and applications, most photoresponsive materials still rely on synthetic chromophores as light-sensing moieties, leaving the diverse protein-based photoreceptors untapped. In this thesis, we developed a new category of protein-based photoresponsive hydrogels by combining the use of recombinant DNA technology, a robust protein assembly strategy known as SpyTag/SpyCatcher chemistry and the newly discovered protein photoreceptor CarH. In Chapter 2, we show the synthesis of the entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. Also shown is the resulting hydrogel that exhibited a rapid gel-sol transition on the light exposure. In Chapter 3, we demonstrate that the hydrogel composed of physically self-assembled CarHC polymers enabled the light-controlled facile release/recovery of human mesenchymal stem cells (hMSCs), 3T3 fibroblasts and PC12 cells f

We report the robust growth of an entirely protein-based, photo- and thermoresponsive Layer-by-Layer nanofilm using genetically encoded SpyTag/SpyCatcher chemistry. The process was facilitated by AdoB12-induced tetramerization of photoreceptor proteins. Protein cargos can be released from the film in a light-dependent manner, showing its potential for therapeutic protein delivery.

Thanks to the precise control over their structural and functional properties, genetically engineered protein-based hydrogels have emerged as a promising candidate for biomedical applications. Given the growing demand for creating stimuli-responsive “smart” hydrogels, here we show the synthesis of entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. The resulting hydrogel composed of physically self-assembled CarHC polymers exhibited a rapid gel-sol transition on light exposure, which enabled the facile release/recovery of 3T3 fibroblasts and human mesenchymal stem cells (hMSCs) from 3D cultures while maintaining their viability. A covalently cross-linked CarHC hydrogel was also designed to encapsulate and release bulky globular proteins, such as mCherry, in a light-dependent manner. The direct assembly of stimuli-responsive proteins into hydrogels represents a versatile strategy for designing dynamically tunable materials.

Thanks to the precise control over their structural and functional properties, genetically engineered protein-based hydrogels have emerged as a promising candidate for biomedical applications. Given the growing demand for creating stimuli-responsive “smart” hydrogels, here we show the synthesis of entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. The resulting hydrogel composed of physically self-assembled CarHC polymers exhibited a rapid gel-sol transition on light exposure, which enabled the facile release/recovery of 3T3 fibroblasts and human mesenchymal stem cells (hMSCs) from 3D cultures while maintaining their viability. A covalently cross-linked CarHC hydrogel was also designed to encapsulate and release bulky globular proteins, such as mCherry, in a light-dependent manner. The direct assembly of stimuli-responsive proteins into hydrogels represents a versatile strategy for designing dynamically tunable materials.

Thanks to the precise control over their structural and functional properties, genetically engineered protein-based hydrogels have emerged as a promising candidate for biomedical applications. Given the growing demand for creating stimuli-responsive “smart” hydrogels, here we show the synthesis of entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions. The resulting hydrogel composed of physically self-assembled CarHC polymers exhibited a rapid gel-sol transition on light exposure, which enabled the facile release/recovery of 3T3 fibroblasts and human mesenchymal stem cells (hMSCs) from 3D cultures while maintaining their viability. A covalently cross-linked CarHC hydrogel was also designed to encapsulate and release bulky globular proteins, such as mCherry, in a light-dependent manner. The direct assembly of stimuli-responsive proteins into hydrogels represents a versatile strategy for designing dynamically tunable materials.

We report the results of our classification-based machine translation model, built upon the framework of a recurrent neural network using gated recurrent units. Unlike other RNN models that attempt to maximize the overall conditional log probability of sentences against sentences, our model focuses a classification approach of estimating the conditional probability of the next word given the input sequence. This simpler approach using GRUs was hoped to be comparable with more complicated RNN models, but achievements in this implementation were modest and there remains a lot of room for improving this classification approach., Comment: 7 pages, 1 figure; graduate course research project

The purple bacteria Rhodobacter sphaeroides serve as a promising biocatalyst in the photo-microbial fuel cell system (photo-MFC). This gram-negative species performs highly efficient anoxygenic photosynthesis that ensures an anaerobic environment in the anode compartment. Previous studies incorporating R. sphaeroides into photo-MFC were conducted using platinum as the anode electrode. In this study, we detected a steady current generation of R. sphaeroides in a bioelectrochemical system where glassy carbon was the working electrode and a typical growth medium was the electrolyte. The bioelectricity generation synchronized with the supplementation of reduced carbon source and showed immediate response to illumination, which strongly indicated the correlation between the observed current and the cytoplasmic quinone activity. Modifications of the endogenous electron flows mediated by quinone pool are shown to have significantly enhanced the bioelectricity generation. We anticipate that the findings in this study would advance future optimization of R. sphaeroides as an anode strain, as well as facilitate the study of bioenergetics in photosynthetic bacteria. © 2016 Elsevier Inc.

The purple bacteria Rhodobacter sphaeroides serve as a promising biocatalyst in the photo-microbial fuel cell system (photo-MFC). This gram-negative species performs highly efficient anoxygenic photosynthesis that ensures an anaerobic environment in the anode compartment. Previous studies incorporating R. sphaeroides into photo-MFC were conducted using platinum as the anode electrode. In this study, we detected a steady current generation of R. sphaeroides in a bioelectrochemical system where glassy carbon was the working electrode and a typical growth medium was the electrolyte. The bioelectricity generation synchronized with the supplementation of reduced carbon source and showed immediate response to illumination, which strongly indicated the correlation between the observed current and the cytoplasmic quinone activity. Modifications of the endogenous electron flows mediated by quinone pool are shown to have significantly enhanced the bioelectricity generation. We anticipate that the findings in this study would advance future optimization of R. sphaeroides as an anode strain, as well as facilitate the study of bioenergetics in photosynthetic bacteria. © 2016 Elsevier Inc.

The purple bacteria Rhodobacter sphaeroides serve as a promising biocatalyst in the photo-microbial fuel cell system (photo-MFC). This gram-negative species performs highly efficient anoxygenic photosynthesis that ensures an anaerobic environment in the anode compartment. Previous studies incorporating R. sphaeroides into photo-MFC were conducted using platinum as the anode electrode. In this study, we detected a steady current generation of R. sphaeroides in a bioelectrochemical system where glassy carbon was the working electrode and a typical growth medium was the electrolyte. The bioelectricity generation synchronized with the supplementation of reduced carbon source and showed immediate response to illumination, which strongly indicated the correlation between the observed current and the cytoplasmic quinone activity. Modifications of the endogenous electron flows mediated by quinone pool are shown to have significantly enhanced the bioelectricity generation. We anticipate that the findings in this study would advance future optimization of R. sphaeroides as an anode strain, as well as facilitate the study of bioenergetics in photosynthetic bacteria. © 2016 Elsevier Inc.

The photosynthetic Rhodobacter species are promising alternative expression hosts in bioproduction and biorefinery due to their unique metabolic capacities. With prominent inner membrane areas and efficient endogenous translocation machineries, they are especially attractive for membrane protein expression. However, codon usage bias could be a limitation in the engineering of Rhodobacter species and has seldom been investigated. In this study, we tackled the codon bias of Rhodobacter by functionally expressing 8 rare tRNAs of Rhodobacter sphaeroides with a multi-copy vector. The impact of tRNA supplementation was evaluated through monitoring expression levels of two heterologous proteins with different phylogenetic origins, a membrane subunit of the riboflavin transporter, RibU, from Lactobacillus acidophilus La-14 and a decaheme cytochrome, MtrA, from Shewanella oneidensis. Our results showed that the performances were closely related to medium composition and rare codon percentages of raw DNA sequences. Provision of rare tRNAs has increased RibU production by 7.7-folds and 2.86-fold in minimal medium and rich medium, respectively, while MtrA levels were increased by 1-fold in minimal medium. The present study confirms the presence of codon bias in R. sphaeroides and offers a facile tool for improving heterologous expression of rare-codon containing genes. We anticipate that this tRNA supplementation system can be further extended to other species of Rhodobacter, and thus will facilitate the engineering of purple bacteria for interesting applications in microbial technology.

The photosynthetic Rhodobacter species are promising alternative expression hosts in bioproduction and biorefinery due to their unique metabolic capacities. With prominent inner membrane areas and efficient endogenous translocation machineries, they are especially attractive for membrane protein expression. However, codon usage bias could be a limitation in the engineering of Rhodobacter species and has seldom been investigated. In this study, we tackled the codon bias of Rhodobacter by functionally expressing 8 rare tRNAs of Rhodobacter sphaeroides with a multi-copy vector. The impact of tRNA supplementation was evaluated through monitoring expression levels of two heterologous proteins with different phylogenetic origins, a membrane subunit of the riboflavin transporter, RibU, from Lactobacillus acidophilus La-14 and a decaheme cytochrome, MtrA, from Shewanella oneidensis. Our results showed that the performances were closely related to medium composition and rare codon percentages of raw DNA sequences. Provision of rare tRNAs has increased RibU production by 7.7-folds and 2.86-fold in minimal medium and rich medium, respectively, while MtrA levels were increased by 1-fold in minimal medium. The present study confirms the presence of codon bias in R. sphaeroides and offers a facile tool for improving heterologous expression of rare-codon containing genes. We anticipate that this tRNA supplementation system can be further extended to other species of Rhodobacter, and thus will facilitate the engineering of purple bacteria for interesting applications in microbial technology.

The photosynthetic Rhodobacter species are promising alternative expression hosts in bioproduction and biorefinery due to their unique metabolic capacities. With prominent inner membrane areas and efficient endogenous translocation machineries, they are especially attractive for membrane protein expression. However, codon usage bias could be a limitation in the engineering of Rhodobacter species and has seldom been investigated. In this study, we tackled the codon bias of Rhodobacter by functionally expressing 8 rare tRNAs of Rhodobacter sphaeroides with a multi-copy vector. The impact of tRNA supplementation was evaluated through monitoring expression levels of two heterologous proteins with different phylogenetic origins, a membrane subunit of the riboflavin transporter, RibU, from Lactobacillus acidophilus La-14 and a decaheme cytochrome, MtrA, from Shewanella oneidensis. Our results showed that the performances were closely related to medium composition and rare codon percentages of raw DNA sequences. Provision of rare tRNAs has increased RibU production by 7.7-folds and 2.86-fold in minimal medium and rich medium, respectively, while MtrA levels were increased by 1-fold in minimal medium. The present study confirms the presence of codon bias in R. sphaeroides and offers a facile tool for improving heterologous expression of rare-codon containing genes. We anticipate that this tRNA supplementation system can be further extended to other species of Rhodobacter, and thus will facilitate the engineering of purple bacteria for interesting applications in microbial technology.

Using sodium sulphite as the reducing agent, the recovery of noble metals in a chlorination-leaching solution by potential-controlled reduction was investigated. Results show that when the reduction potential of Au is controlled at 530-550 mV, 98% Au in the chlorination-leaching solution is reduced and precipitated as raw-gold powder while Pt, Pd and Te are almost not reduced. The content of Au in the obtained raw-gold powder is above 98% and that of Se, Te, Cu and Pb is all lower than 0.10% (mass fraction). Also, the potential value of gold reduction is very adaptable to many different kinds of chlorination-leaching solutions that have various concentrations of Au or H+. Then when the reduction potential of Pt/Pd is controlled in 390-420 mV, the concentration of Au, Pt and Pd in the precipitated-gold solution can be reduced to below 1 mg/l while most of Te still remains. The content of noble metals in the collected Pt-Pd concentrate is remarkably high and that of impurities comparatively low. In addition, the determined potential value of Pt/Pd reduction shows great adaptability to those precipitated-gold solutions with different Pt/Pd concentrations or acidity as well as reaction temperature. Accordingly, the noble metals in the chlorination-leaching solutions will selectively precipitate and preliminary separate from other elements by the potential-controlled reduction method., Using sodium sulphite as the reducing agent, the recovery of noble metals in a chlorination-leaching solution by potential-controlled reduction was investigated. Results show that when the reduction potential of Au is controlled at 530-550 mV, 98% Au in the chlorination-leaching solution is reduced and precipitated as raw-gold powder while Pt, Pd and Te are almost not reduced. The content of Au in the obtained raw-gold powder is above 98% and that of Se, Te, Cu and Pb is all lower than 0.10% (mass fraction). Also, the potential value of gold reduction is very adaptable to many different kinds of chlorination-leaching solutions that have various concentrations of Au or H+. Then when the reduction potential of Pt/Pd is controlled in 390-420 mV, the concentration of Au, Pt and Pd in the precipitated-gold solution can be reduced to below 1 mg/l while most of Te still remains. The content of noble metals in the collected Pt-Pd concentrate is remarkably high and that of impurities comparatively low. In addition, the determined potential value of Pt/Pd reduction shows great adaptability to those precipitated-gold solutions with different Pt/Pd concentrations or acidity as well as reaction temperature. Accordingly, the noble metals in the chlorination-leaching solutions will selectively precipitate and preliminary separate from other elements by the potential-controlled reduction method.