Converting A Dataset to JSON using .net 3.5 in C#

public static string GetJSONString(DataTable Dt)
{

string[] StrDc = new string[Dt.Columns.Count];
string HeadStr = string.Empty;

for (int i = 0; i < Dt.Columns.Count; i++)
{

StrDc[i] = Dt.Columns[i].Caption;

HeadStr += """ + StrDc[i] + "" : "" + StrDc[i] + i.ToString() + "¾" + "",";
}

HeadStr = HeadStr.Substring(0, HeadStr.Length - 1);

StringBuilder Sb = new StringBuilder();
Sb.Append("{"" + Dt.TableName + "" : [");

for (int i = 0; i < Dt.Rows.Count; i++)
{

string TempStr = HeadStr;
Sb.Append("{");

for (int j = 0; j < Dt.Columns.Count; j++)
{

TempStr = TempStr.Replace(Dt.Columns[j] + j.ToString() + "¾", Dt.Rows[i][j].ToString());
}

Sb.Append(TempStr + "},");
}

Sb = new StringBuilder(Sb.ToString().Substring(0, Sb.ToString().Length - 1));
Sb.Append("]}");

return Sb.ToString();
}