How to serialize the tree view control in C#

namespace TreeViewControl
{
    [Serializable]
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string n = textBox1.Text;
            if (treeView1.SelectedNode == null)
            {
                treeView1.Nodes.Add(n, n);
            }
            else
            {
                treeView1.SelectedNode.Nodes.Add(n, n);
            }
        }
    }
  }